University of Groningen Genotyping and phenotyping epilepsies of childhood Vlaskamp, Danique

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Genotyping and phenotyping epilepsies of childhood

Vlaskamp, Danique

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Vlaskamp, D. (2018). Genotyping and phenotyping epilepsies of childhood. Rijksuniversiteit Groningen.

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525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp Processed on: 29-10-2018 Processed on: 29-10-2018 Processed on: 29-10-2018

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&KDSWHU

PRRT2-related phenotypes in patients

with a 16p11.2 deletion

Published as: DRM Vlaskamp, PMC Callenbach, P Rump, LAA Giannini, EH Brilstra, T Dijkhuizen, YJ Vos, AMF van der Kevie-Kersemaekers, J Knijnenburg, N de Leeuw, R van Minkelen, CAL Ruivenkamp,

APA Stegmann, OF Brouwer, CMA van Ravenswaaij-Arts. European journal of medical genetics, 2018. In press.

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Danique RM Vlaskamp 1,2_{, Petra MC Callenbach *}1_{, Patrick Rump *}2_{, Lucia AA Giannini}2_{, Eva H}

Brilstra 3_{, Trijnie Dijkhuizen}2_{, Yvonne J. Vos}2_{, Anne-Marie F van der Kevie-Kersemaekers}4_{, Jeroen}

Knijnenburg 5_{, Nicole de Leeuw}6_{, Rick van Minkelen}5_{, Claudia AL Ruivenkamp}7_{, Alexander PA}

Stegmann 8_{, Oebele F Brouwer}1_{, Conny MA van Ravenswaaij-Arts}2

1 _{University of Groningen, University Medical Center Groningen, Department of Neurology,}

Groningen, the Netherlands. 2_{University of Groningen, University Medical Center Groningen,}

Department of Genetics, Groningen, the Netherlands. 3_{University Medical Center Utrecht,}

Department of Genetics, Utrecht, the Netherlands. 4_{Academic Medical Center, Department}

of Genetics, Amsterdam, the Netherlands. 5_{Erasmus Medical Center, Department of Genetics,}

Rotterdam, the Netherlands. 6_{Radboud University Medical Center, Department of Genetics,}

Nijmegen, the Netherlands. 7_{Leiden University Medical Center, Department of Genetics, Leiden,}

the Netherlands. 8_{Maastricht University Medical Center, Department of Genetics, Maastricht, the}

Netherlands. * Both authors contributed equally to this work

Acknowledgements. We are grateful to the patients and their parents/caretakers for

participating in this study and to the physicians for including their patients. We thank Jackie Senior for editing the manuscript and Rita Dirks for submitting the patients with 16p11.2 deletions to the European Cytogeneticists Association Register of Unbalanced Chromosome Aberrations.

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ABSTRACT

We studied the presence of benign infantile epilepsy (BIE), paroxysmal kinesigenic dyskinesia (PKD), and PKD with infantile convulsions (PKD/IC) in patients with a 16p11.2 deletion including

PRRT2 or with a PRRT2 loss-of-function sequence variant. Index patients were recruited from

seven Dutch university hospitals. The presence of BIE, PKD and PKD/IC was retrospectively evaluated using questionnaires and medical records. We included 33 patients with a 16p11.2 deletion: three (9%) had BIE, none had PKD or PKD/IC. Twelve patients had a PRRT2 sequence variant: BIE was present in four (p=0.069), PKD in six (p<0.001) and PKD/IC in two (p=0.067). Most patients with a deletion had undergone genetic testing because of developmental problems (87%), whereas all patients with a sequence variant were tested because of a movement disorder (55%) or epilepsy (45%). BIE, PKD and PKD/IC clearly showed incomplete penetrance in patients with 16p11.2 deletions, but were found in all and 95% of patients with a PRRT2 sequence variant in our study and a large literature cohort, respectively. Deletions and sequence variants have the same underlying loss-of-function disease mechanism. Thus, diﬀerences in ascertainment have led to overestimating the frequency of BIE, PKD and PKD/IC in patients with a PRRT2 sequence variant. This has important implications for counseling if genome-wide sequencing shows such variants in patients not presenting the PRRT2-related phenotypes.

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INTRODUCTION

PRRT2 (MIM 614386) has been identiﬁed as a causal gene for benign infantile epilepsy (BIE),

paroxysmal kinesigenic dyskinesia (PKD), and paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC).1–3_{These clinical entities reﬂect the core of the PRRT 2-related phenotypic} spectrum.4 _{Other epilepsies, movement disorders and (hemiplegic) migraine have been reported} to be possibly related to PRRT2 sequence variants.4

PRRT2 encodes for proline-rich transmembrane protein 2 that interacts with SNAP25 in

glutamatergic synapses in the brain to modulate glutamate release.1–3, 5_{PRRT2 sequence variants} have been shown to result in a loss-of-function of PRRT2, impaired SNAP25 interaction, raised intracellular glutamate levels and increased neuronal hyperexcitability.3, 5

Chromosome 16p11.2 deletions including PRRT2 are associated with the 16p11.2 microdeletion syndrome (MIM 611913). We expected that 16p11.2 deletions are also associated with PRRT2-related phenotypes, because deletions and sequence variants of PRRT2 share an underlying loss-of-function disease mechanism. So far, only six cases with a 16p11.2 deletion and PKD (n=4) or PKD/IC (n=2) have been reported.6–11_{Previous large 16p11.2 deletion cohort studies reported} seizures in 24-31% of patients, dystonia in 1% and paroxysmal dyskinesia in 5% without classifying these phenotypes as BIE, PKD or PKD/IC.12–14

We systematically evaluated the presence of the PRRT2-related phenotypes BIE, PKD, and PKD/IC in patients with a 16p11.2 deletion including PRRT2, and compared these frequencies with those seen in patients with a PRRT2 sequence variant.

METHODS

We identiﬁed 129 Dutch-speaking patients with a 16p11.2 deletion including PRRT2 in seven Dutch university medical centers (UMCs). Five patients were not approached for participation (two were deceased, two had an additional disease-associated 22q11.2 deletion, and one was lost to follow-up before this study). Forty of 124 (32%) patients agreed to participate, including 33/40 (83%) index patients from 33 families.

Following the same strategy, we identiﬁed 43 patients with a PRRT2 sequence variant in three UMCs. One patient was involved in another study and not contacted. Fifteen (36%) patients agreed to participate, including 12/15 (80%) index patients from 12 families.

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Processed on: 29-10-2018 PDF page: 161PDF page: 161PDF page: 161PDF page: 161 All patients or their parents/caregivers gave written consent for participation and completed

a questionnaire containing (1) a PKD Screening questionnaire, (2) a Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation questionnaire and (3) questions on epilepsy (seizure onset, remission, frequency and semiology), school performance and development, height, weight and family history.15,16 _{An English version of the questionnaire is} available on request.

Phenotypes were compared between index patients with a 16p11.2 deletion (n=33) and a PRRT2 sequence variant (n=12). To increase the validity of any observed diﬀerences, we compared the phenotypes of patients with a 16p11.2 deletion in our cohort (n=33) with those of patients with a heterozygous PRRT2 sequence variant reported in the large review cohort of Ebrahimi-Fakhari (n=1423, excluding patients with bi-allelic PRRT2 sequence variants (n=15) or a 16p11.2 deletion (n=6)).4

Additional information on methods is given in the Supplemental Methods.

RESULTS

We included 33 index patients with the recurrent ~600kb BP4-BP5 16p11.2 deletion (Supplementary Figure 1) and 12 index patients with a disease-associated PRRT2 sequence variant: c.649dupC; p.(Arg217Profs*8) (n=10), c.629dupC; p.(Ala211Serfs*14) (n=1), or c.824C>T; p.(Ser275*) (n=1) (NM_145239.2, Supplementary Table 1). All variants were added to public databases (see Supplementary methods for more information). Patients with a 16p11.2 deletion most often underwent genetic testing because of developmental delay (87%), while those with a PRRT2 sequence variant were tested because of a movement disorder (55%) or epilepsy (45%) (Table 1). Patients with a 16p11.2 deletion less often had a PRRT2-related phenotype than those with a

PRRT2 sequence variant (9% vs. 100%, p<0.001) (Table 1). These phenotypes concerned BIE (9% vs.

33%, p=0.069), PKD (0% vs. 50%, p<0.001) and PKD/IC (0% vs. 17%, p=0.067) (See Tables 2 and 3 for epilepsy and movement disorder phenotypes, respectively). Comparisons between patients with a 16p11.2 deletion in our cohort and those with a PRRT2 sequence variant from the review cohort showed significant differences for all PRRT2-related phenotypes (Table 1). The presence of other epilepsies, movement disorders, hemiplegic migraine and migraine as possible PRRT2-related phenotypes did not significantly differ between the three groups (Tables 1-3, see Supplementary Table 2 for migraine phenotypes).

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T

able 1:

P

henot

ypes of patients with a 16p11.2 deletion or a

PRRT2

sequence var

iant in our cohor

t and the lit

eratur e Pa ti e n ts w it h a 1 6 p 11 .2 de let ion (n = 3 3) Pa ti e n ts w it h a PR RT 2 se quenc e var ian t (n = 12) p-v a lu e 1 Pa ti e n ts w it h a PR RT 2 se quenc e var ian t from th e re view c o hor t (n = 14 2 3) 2 p-v a lu e 3 P a tie n t char ac te rist ic s at inc lusion in study Male ( % ) 19 ( 57 .6 ) 4 ( 33 ) 0. 18 9 N A N A M edian a g e in ye ar s ( range ) 12 .4 ( 3. 8 – 3 7.1 ) 21 .5 ( 4. 5 – 4 8. 7) 0. 0 2 3 NA NA PR RT 2 -r e late d phenot ypes Dia g nos is in BIE – P K D – P K D /IC sp ec tr um ( % ) 3 ( 9. 1) 12 ( 10 0) < 0. 0 0 1 13 52 (9 5. 0) < 0. 0 0 1 - BIE ( % ) 3 ( 9. 1) 4 ( 33 .3 ) 0.0 69 598 ( 42 .0 ) < 0. 0 0 1 - P K D ( % ) 0 ( -) 6 ( 50.0 ) < 0. 0 0 1 55 3 ( 38 .9 ) < 0. 0 0 1 - P K D /IC ( % ) 0 ( -) 2 ( 16 .7) 0.0 67 20 1 ( 14 .1 ) 0. 0 1 0 P ossib le PR RT 2 -r e late d phenot ypes O th er epileps y dia g nos is ( % ) 2 ( 6. 1) 1 ( 8. 3) 1.0 00 51 ( 3. 6) 4 0. 34 0 O th er m o vem en t di so rd er dia g nos is ( % ) 1 ( 3.0 ) 0 ( -) 1. 00 0 19 ( 1. 3) 5 0. 37 0 H emip le gic migr ain e ( % ) 1/3 1 ( 3. 2) 3 ( 25 .0 ) 0.0 59 34 ( 2. 4) 0. 53 4 Migr ain e or pr ob ab le migr ain e ( % ) 4/3 1 ( 12. 9) 1 ( 8. 3) 1.0 00 68 (4 .8 ) 0.0 63 1 6 p 11 .2 de let ion -r e late d phenot ypes D evelopm en ta l pr ob lems ( % ) 33 ( 10 0) 1 ( 8. 3) < 0. 0 0 1 NA NA - S p ec ial e d uc ation in thos e > 4 ye ar s ( % ) 29 /3 2 ( 90. 6) 0/ 11 ( -) < 0. 0 0 1 20 (1 .4 ) 6 <0. 0 0 1 - P rob lems in m o to r developm en ta l ( % ) 28 ( 84 .8 ) 1 ( 8. 3) < 0. 0 0 1 NA NA - P rob lems in langua ge developm en t ( % ) 32 ( 97 .0 ) 0 ( -) < 0. 0 0 1 NA NA M edian a g e in m o n th s a t - s it ting ( range , k n ow n in n ) 10 .0 ( 6.0 – 4 8.0 , 2 8) 9.0 (7 .0 – 1 1.0 , 7) 0. 34 0 N A N A - w alk ing ( range , k n ow n in n ) 19 .8 ( 12 .0 – 3 0.0 , 3 0) 7 14 .5 ( 11 .0 – 22 .0 , 8 ) <0. 0 0 1 NA NA - sp ea ki ng ﬁr st wor d ( range , k n ow n in ) 17 .5 ( 9.0 – 8 4.0 , 2 4) 7 11 .5 (9 .0 – 1 2.0 , 6 ) 0. 0 0 3 NA NA - sp ea ki ng c o mpr eh en sivel y ( range , k n ow n in n ) 48 .0 ( 18 .0 – 7 2.0 , 1 5) 7 18 .0 ( 16 .0 – 3 0.0 , 6 ) 0. 0 0 1 NA NA O b es it y ( % ) 5/25 ( 20.0 ) 0 ( -) 0. 15 2 N A N A

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Pa ti e n ts w it h a 1 6 p 11 .2 de let ion (n = 3 3) Pa ti e n ts w it h a PR RT 2 se quenc e var ian t (n = 12) p-v a lu e 1 Pa ti e n ts w it h a PR RT 2 se quenc e var ian t from th e re view c o hor t (n = 14 2 3) 2 p-v a lu e 3 Indicat ions for genet ic test ing - E p ileps y ( % ) 3/3 0 ( 10.0 ) 5/ 11 ( 45 .4 ) 0. 0 2 2 NA NA - M o vem en t di so rd er s ( % ) 0/3 0 ( -) 6/ 11 (5 4. 5) <0. 0 0 1 NA NA - ( H emip le gic ) Migr ain e ( % ) 0/3 0 ( -) 1/ 11 ( 9. 1) 0. 28 6 N A N A - D evelopm en ta l pr ob lems ( % ) 26/3 0 ( 86 .7) 0/ 11 (-) <0. 0 0 1 NA NA - O b es it y ( % ) 3/3 0 ( 10.0 ) 0/ 11 ( -) 0. 55 1 N A N A - O th er ( d ys m o rp hi sm s, b eha vior al pr ob lems, famil y hi st o ry ) ( % ) 15 /3 0 ( 50. 0) 2/ 11 (1 8. 2) 0. 08 5 N A N A If p ati en ts ha d missin g info rm ati o n, a d en o minat o r is gi ven that repr es en ts th e numb er of p atien ts with k n ow n infor ma tion on th is v ar iab le . I f n o d en o minat o r is gi ven, th ere w as info rm ati o n o n all p ati en ts . P-va lu es in b o ld were c o nsi d ere d si gni ﬁc an t ( p < 0. 05 ). 1 p -v alu es o f c o mp ar is o n s b et w ee n p ati en ts w ith a 1 6p 11 .2 d el eti o n an d p ati en ts in o u r c o h o rt w ith a PR RT 2 se qu en ce v ar ian t. Fish er ’s e xa ct t es ts were us ed fo r c at eg o ri cal dat a an d M ann -W hi tn ey U t es ts fo r c o n tinu o us v ar iab le s. 2 All p ati en ts w ith a h et ero zyg o us PR RT 2 se qu en ce v ar ian t in clu d ed in th e rev iew s tu d y by Eb ra himi et al . ( se e al so m eth o d s s ec ti o n ). 3 p -v alu es o f c o mp ar is o n s b et w ee n p ati en ts w ith a 1 6p 11 .2 d el eti o n an d p ati en ts f ro m th e rev iew c o h o rt w ith a PR RT 2 se qu en ce v ar ian t. F ish er ’s ex ac t t es ts were us ed fo r c at eg o ri cal dat a an d M ann -W hi tn ey U t es ts fo r c o n tinu o us v ar iab le s. 4 O th er ep ileps y dia g n o se s in clu d ed ep ileps y/ sei zu re s n o t oth er w is e sp eci ﬁe d , feb ril e s ei zure s p lus , abs en ce s ei zure s, D ra vet s yn d ro m e, g en er ali ze d ep ileps y w ith feb ril e s ei zure s, W es t s yn d ro m e an d b eni gn R o lan d ic ep ileps y. 5 O th er m ovem en t dis o rd er dia g n o se s in clu d ed p arox ysmal n o n -k in esi g eni c d ysk in es ia , p arox ysmal e xer cis e -i n du ce d d ysk in es ia , ep is o d ic at ax ia , w ri ter ’s cr amp an d p arox ysmal t o rt ic o llis . 6 Pa tien ts with in tel le ctual di sabi lit y or le ar n ing d is abi lities . 7 Th re e femal es a g ed 6 year s, 2 1 year s† an d 2 9 year s were n o t ab le t o w alk o r t alk . A b b rev iati o n s: B IE = b eni gn inf an til e ep ileps y, NA = n o t a vailab le , P K D = p arox ysmal k in esi g eni c d ysk in es ia , P K D /I C = p arox ysmal k in esi g eni c d ysk in es ia w ith inf an til e c o n vul si o n s.

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T

able 2:

Epilepsy phenot

ypes in patients with a 16p11.2 deletion or a

PRRT2 sequence var iant Pt S e x , a g e i n ye a rs

Epilepsy syndrome diagnosis

PK D Ag e a t o n se t o f seizures Ag e a t re mission of seizures To ta l numb e r of seizures Seizure t y pe Ant i-e p il e p ti c d ru g s ( e ff e ct ) E E G a t o n se t o f epi lep sy B ra in i m a g in g De v e lop -men tal problems 1 6 p 11 .2 de let ions (n =5 ) 2 F, 3 BIE N o 4m 12 m 10 -25 FM S ( tonic -c lonic ) LE V ( + ) Fu nc tional di so rd er le ft fr o n to temp o ral with epileptifor m abnor malities ? W ide p er ip h er al ce re b rosp inal flui d sp ac es (L > R) on MRI DD 3F , 1 5 BIE No 4m 4y >2 5 FI A S, F BT C S V PA (+ ) N orm al MRI norm al DD /I D 42 F, 2 9 BIE N o 5m 7m 1-5 U nk n o w n U nk n ow n U nk n o w n U nk n ow n S ever e DD /I D 1M , 1 3 F o ca l epi lep sy N o 12 y N o 20 /da y FMS ( at o nic ), F IA S V PA ( + ) U nk now n U nk n ow n D D /ID 33 F, 2 1 † F o ca l epi lep sy N o 0m 21 y † 10 -5 0/ d ay U TS, F IA S, F BT C S V PA ( + ), L TG (u n kn o w n) Un kn ow n U n kn o w n Se ve re D D /I D PR R T 2 s e q u e n ce v a ri a n ts ( n = 7 ) 6 M , 4 BF IE N o 5m 6m 5-10 FM S ( tonic ) LE V ( + ) N o t p er for m ed N o t p er for m ed N o 10 F, 2 4 BF IE N o Un kn ow n U n kn o w n Un kn ow n U n kn o w n Un kn ow n U n kn o w n Un kn ow n N o 17 F, 1 3 BIE Yes 8m 8m 5 FM S ( tonic -c lonic ) PH B ( + ) N or mal Ul tr as o u n d norm al No 35 F, 2 2 BF IE Yes 8m 8m 7 FM S ( tonic -c lonic ) V PA ( + ) N or mal MR I nor mal N o 36 F, 5 BF IE No 6m 2y >2 5 FBT C S LE V (-), C BZ (-), LT G ( + ) Ep ileptifor m a ctiv it y lef t o cc ., s o m etim es spr ea d ing t o r igh t oc c. MRI norm al N o 48 F, 48 BF IE N o Un kn ow n 1y U n kn o w n Un kn ow n U n kn o w n Un kn ow n U n kn o w n N o 7F , 3 1 Unc lassi fi e d N o 28 y 29 y 1-5 U TC S U nk n o w n U n kn ow n U nk n o w n N o Tr eat m en t effe ct : + t reat m en t re sp o n se , d efin ed as > 50 % s ei zure f re q u en cy re du ct io n, - n o t reat m en t re sp o n se . A b b rev iati o n s: B IE = b eni gn inf an til e ep ileps y, B FIE = b eni gn f amilial inf an til e ep ileps y, CB Z = c ar b ama zep in e, D D = d evel o p m en ta l d elay , F B TC S = fo ca l t o b ilat er al t o ni c-cl o n ic s ei zure s, F IA S = fo ca l imp aire d aw aren es s s ei zure s, F M S = fo ca l m o to r s ei zure s, ID = in te lle ct u al dis ab ili ty , L = l ef t, LE V = l evetir ac et am, L TG = lam o tr ig in e, o cc . = o ccip it al, P H B = p h en o b ar b it al, P K D = p arox ysmal k in esi g en ic d ysk in es ia , R = r igh t, U TC S = unk n ow n o n se t t o ni c-cl o n ic s ei zure , U TS = unk n ow n o n se t t o ni c s ei zure , V PA = v alp ro ic a ci d .

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Table 3: Movement disorders in patients with a 16p11.2 deletion or a PRRT2 sequence variant

Pt. Sex, age in

years

Movement

disorder BIE Age at onset Age at remissionMotor DD

Previous medication (effect) Current medication 1 (effect) 16p11.2 deletions (n=1) 3 F, 15 Myoclonic dystonia with cortical myoclonus

Yes Birth No Yes VPA (+, but side-_eﬀects) CZP (+)

PRRT2 sequence variants (n=8

7 F, 31 PKD No 9y No No CBZ (+) None

8 M, 18 PKD No 14y 16y No None CBZ (+)

17 F, 13 PKD Yes 10y 12y No CZP (-) CBZ (+)

20 F, 20 PKD No 8y 19y No None None

35 F, 22 PKD Yes 14y 14y No None OXC (+)

44 M, 34 PKD No 8y No No L-DOPA (-),CBZ

(+, but side-eﬀects) None

49 M, 24 PKD No 10y No No CBZ (+), LEV (-), OXC

(side-eﬀects), GBP (-) LTG (+)

53 F, 18 PKD No 15y 16y Yes 2 _None _{CBZ (+)}

Treatment eﬀect: + treatment response, - no treatment response. 1_{At last moment of contact with specialist.} 2 _Attributed

to perinatal asphyxia. Abbreviations: BIE = benign infantile epilepsy, CBZ = carbamazepine, CZP = clonazepam, DD = developmental delay, GBP = gabapentin, L-DOPA = levodopa, LTG = lamotrigine, OXC = oxcarbazepine, PKD = paroxysmal kinesigenic dyskinesia, VPA = valproic acid.

DISCUSSION

We found that only a minority of patients with a 16p11.2 deletion in our cohort suﬀered from BIE (9%) while none had PKD or PKD/IC. In comparison, patients with a PRRT2 sequence variant in our cohort (100%) and a review cohort (95%) had these PRRT2-related phenotypes signiﬁcantly more often.4

It is unlikely that phenotypic differences between the two different genotype cohorts are due to differences in the underlying PRRT2 disease mechanism. First, PRRT2-related phenotypes occurred in both genotype groups in our study and other studies.6–11_{Second, both genotypes cause a} loss-of-function of PRRT2. The p.(Arg217Profs*8) variant, found in most patients of our (83%) and the review (79%) cohort, results in a PRRT2 loss-of-function without a dominant-negative effect.3–5 Patients with 16p11.2 deletions have a 50% reduced expression of PRRT2 and other genes within the deletion region that probably explains their additional problems.17_{In theory, the deletion of} these other genes might have had a protective effect on the patients’ phenotypes, but no clear evidence for this hypothesis exists so far.

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Processed on: 29-10-2018 PDF page: 166PDF page: 166PDF page: 166PDF page: 166 It seems most likely that diﬀerences in ascertaining patients underlie the diﬀerences in

PRRT2-related phenotypes observed in patients with a 16p11.2 deletion versus a PRRT2 sequence variant. The frequency of phenotypes has probably been overestimated in patients with a

PRRT2 variant, who most often underwent genetic testing because of a movement disorder

or epilepsy. The high frequency of the recurrent c.649dupC; p.(Arg217Profs*8) PRRT2 variant in individuals included in the ExAC Database (1.3%, n=401/32,017; Exac version 0.3.1) seems to support this hypothesis, although the frequency in the gnomAD Database is substantially lower (0.05%, n=8/14,859; gnomAD version r2.0.2).18_{This difference might be related to the used data} (whole exome versus whole genome data) or whether DNA amplification was performed, as previously suggested by the relatively high frequency of this variant in the Exome Variant Server database that uses amplification.19 _{A compatible influence of ascertainment might be present in} the published review cohort. The inclusion of index cases in calculating penetrance of PRRT2 in other studies has probably resulted in an overestimated disease penetrance for PKD (60%) and BIE (60-90%).20,21 _{A lower penetrance (48%) has been found in a single family with 23 relatives} with PRRT2 sequence variants (Family 1, excluding the index patient).20,22_{Reduced penetrance} is also known for other clinical features associated with the 16p11.2 BP4-BP5 deletion.12–14 _The low frequency of PRRT2-related phenotypes in our patients with 16p11.2 deletions is in line with two large previous studies showing the presence of any seizures in 24% (n=49/195) and 27% (n=22/83), paroxysmal dyskinesia in 5% (n=12/233) and dystonia in 1% (n=1/83), emphasizing the incomplete penetrance of BIE and PKD.12–14 _{However, in our small cohort, we might have} underestimated the presence of PRRT2-related phenotypes. First, BIE occurred long time ago in some patients, leading to recall bias, and may have a low seizure-frequency, leading to missed diagnoses. Second, three patients had unwitnessed incidents, but these occurred too late for a diagnosis of BIE. Last, some patients were too young to fully exclude PKD. It is thus possible that the differences in frequencies between the two patient groups might be partly explained by under-recognition of PRRT2-related phenotypes in the 16p11.2 microdeletion patients.

The observation that the frequency of PRRT2-related phenotypes has thus far been overestimated in patients with a PRRT2 loss-of-function variant is important for counseling, because increasingly used whole exome sequencing (WES) may detect these variants as secondary ﬁndings. Doctors are tempted to use large cohort studies to counsel patients with such unexpected ﬁndings, but should realize that ascertainment bias is always present in these studies.

CONCLUSION

We conclude that 16p11.2 deletions including PRRT2 and PRRT2 sequence variants both lead to the associated phenotypes BIE, PKD or PKD/IC, but with incomplete penetrance. PRRT2-related phenotypes were more commonly found in patients with PRRT2 sequence variants, despite the shared underlying PRRT2 loss-of-function disease mechanism. Ascertainment bias

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Processed on: 29-10-2018 PDF page: 167PDF page: 167PDF page: 167PDF page: 167 has led to an overestimation of the penetrance of BIE, PKD and PKD/IC in patients with a PRRT2

sequence variant. This study is important for the clinical interpretation of PRRT2 sequence variants found by WES in patients without these speciﬁc phenotypes.

WEB RESOURCES

We used the following URLs for data:

Exome Aggregation Consortium (ExAC), http://exac.broadinstitute.org Expression Atlas for gene expression, http://www.ebi.ac.uk

Online Mendelian Inheritance in Man (OMIM), https://www.omim.org UCSC Genome Bioinformatics, https://genome.ucsc.edu

European Cytogeneticists Association Register of Unbalanced Chromosome Aberrations (ECARUCA), http://ecaruca.radboudumc.nl:8080/ecaruca/

Leiden Open Variation Database (LOVD), http://www.lovd.nl/PRRT2

DatabasE of genomiC varIation and Phenotype in Humans using Ensembl Resources (DECIPHER), https://decipher.sanger.ac.uk/

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1 Heron SE, Grinton BE, Kivity S, et al. PRRT2 mutations cause benign familial infantile epilepsy and infantile convulsions with choreoathetosis syndrome. Am J Hum Genet 2012; 90: 152–60.

2 Chen W-J, Lin Y, Xiong Z-Q, et al. Exome sequencing identiﬁes truncating mutations in PRRT2 that cause paroxysmal kinesigenic dyskinesia. Nat Genet 2011; 43: 1252–1255.

3 Lee HY, Huang Y, Bruneau N, et al. Mutations in the Gene PRRT2 Cause Paroxysmal Kinesigenic Dyskinesia with Infantile Convulsions. Cell Rep 2012; 1: 2–12.

4 Ebrahimi-Fakhari D, Saﬀari A, Westenberger A, Klein C. The evolving spectrum of PRRT2 -associated paroxysmal diseases. Brain 2015; 138: 3476–3495.

5 Li M, Niu F, Zhu X, et al. PRRT2 mutant leads to dysfunction of glutamate signaling. Int J Mol Sci 2015; 16: 9134–9151. 6 Dale RC, Grattan-Smith P, Fung VSC, Peters GB. Infantile

convulsions and paroxysmal kinesigenic dyskinesia with 16p11.2 microdeletion. Neurology 2011; 77: 1401–1402. 7 Dale RC, Grattan-Smith P, Nicholson M, Peters GB.

Microdeletions detected using chromosome microarray in children with suspected genetic movement disorders: A single-centre study. Dev Med Child Neurol 2012; 54: 618–623.

8 Lipton J, Rivkin MJ. 16p11.2-related paroxysmal

kinesigenic dyskinesia and dopa-responsive parkinsonism in a child. Neurology 2009; 73: 479-480. 9 Silveira-Moriyama L, Gardiner AR, Meyer E, et al. Clinical

features of childhood-onset paroxysmal kinesigenic dyskinesia with PRRT2 gene mutations. Dev Med Child Neurol 2013; 55: 327–334.

10 Weber A, Köhler A, Hahn A, Neubauer B, Müller U. Benign infantile convulsions (IC) and subsequent paroxysmal kinesigenic dyskinesia (PKD) in a patient with 16p11.2 microdeletion syndrome. Neurogenetics 2013; 14: 251– 253.

11 Termsarasab P, Yang AC, Reiner J, Mei H, Scott SA, Frucht SJ. Paroxysmal kinesigenic dyskinesia caused by 16p11.2 microdeletion. Tremor Other Hyperkinet Mov (N Y) 2014; 4: 274.

12 Shinawi M, Liu P, Kang SL, et al. Recurrent reciprocal 16p11.2 rearrangements associated with global developmental delay, behavioural problems, dysmorphism, epilepsy, and abnormal head size. J Med Genet 2010; 47: 332–341.

13 Steinman KJ, Spence SJ, Ramocki MB, et al. 16p11.2 deletion and duplication: Characterizing neurologic phenotypes in a large clinically ascertained cohort. Am J Med Genet Part A 2016; 170: 2943–2955.

14 Zuﬀerey F, Sherr EH, Beckmann ND, et al. A 600 kb deletion syndrome at 16p11.2 leads to energy imbalance and neuropsychiatric disorders. J Med Genet 2012; 49: 660–668.

15 Tan LCS, Methawasin K, Teng EWL, et al. Clinico-genetic comparisons of paroxysmal kinesigenic dyskinesia patients with and without PRRT2 mutations. Eur J Neurol 2014; 21: 674–678.

16 Steiner TJ, Gururaj G, Andrée C, et al. Diagnosis,

prevalence estimation and burden measurement in population surveys of headache: presenting the HARDSHIP questionnaire. J Headache Pain 2014; 15: 3. 17 Blumenthal I, Ragavendran A, Erdin S, et al. Transcriptional

consequences of 16p11.2 deletion and duplication in mouse cortex and multiplex autism families. Am J Hum Genet 2014; 94: 870-883

18 Lek M, Karczewski KJ, Minikel EV, et al. Analysis of protein-coding genetic variation in 60,706 humans. Nature 2016; 536: 285–291.

19 Huguet G, Nava C, Lemière N, et al., Heterogeneous Pattern of Selective Pressure for PRRT2 in Human Populations, but No Association with Autism Spectrum Disorders. PLoS ONE 2014; 9, e88600. doi:10.1371/journal. pone.0088600

20 Callenbach PMC, van den Boogerd EH, de Coo RFM, et al. Reﬁnement of the chromosome 16 locus for benign familial infantile convulsions. Clin Genet 2005; 67: 517–25. 21 Van Vliet R, Breedveld G, De Rijk-Van Andel J, et al. PRRT2 phenotypes and penetrance of paroxysmal kinesigenic dyskinesia and infantile convulsions. Neurology 2012; 79: 777–784.

22 De Vries B, Callenbach PMC, Kamphorst JT, et al. PRRT2 mutation causes benign familial infantile convulsions. Neurology 2012; 79: 2154–2155.

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SUPPLEMENTAL DATA

SUPPLEMENTAL METHODS

Additional data collection

If any problems related to epilepsy, movement disorders or migraine were reported in the questionnaire, we requested further information from their physicians to conﬁrm a diagnosis of epilepsy, movement disorder and/or migraine, If the information was still inconsistent or unclear, we called the patients or their parents/caregivers to further clarify and classify the reported problems. A local coordinator in each center provided information on the patients’ genotypes and indications for genetic testing.

Phenotypes

For the purpose of this study, a PRRT2-related phenotype involved a diagnosis of BIE, PKD or PKD/IC. Possible PRRT2-related phenotypes included hemiplegic migraine, migraine, other epilepsies than BIE, and other movement disorders than PKD. The presence of epilepsy was determined using the latest definition of the International League Against Epilepsy (ILAE, 2014).1 We classified seizure types and epilepsy syndromes including BIE in accordance with the recent ILAE classifications for seizure types and epilepsy syndromes.2,3 _{We defined treatment response} to anti-epileptic drugs (AED) as >50% seizure frequency reduction. We confirmed a diagnosis of PKD based on the criteria proposed by Bruno et al. and a diagnosis of migraine based on the guidelines of the International Classification of Headache disorders (third edition).4,5 _{In accordance} with the World Health Organization standards, we defined obesity as a body mass index (BMI) ≥30 (adults), a BMI adjusted for age >2 standard deviations (SD) from the median (for children 5-19 years of age), or a weight-for-height >3 SD above the median (for children 0-5 years) using the Dutch growth curves from the Netherlands Organization for Applied Scientific Research.6,7 A family history was positive for epilepsy, PKD or (hemiplegic) migraine, if this phenotype was present in a first- or second-degree relative.

Genotypes

Genes and gene variants were described in accordance with the HUGO Gene Nomenclature Committee (HGNC) and the Human Genome Variation Society (HGVS). The chromosomal coordinates were converted according to the Genome Reference Consortium Human Reference sequence version 37 (GRCh37/hg19). The cDNA positions are presented based on the transcript variant 1 of PRRT2 (NM_145239.2). We added all patients and their variants to public databases. Patients with 16p11.2 deletions were submitted to the European Cytogeneticists Association Register of Unbalanced Chromosome Aberrations (ECARUCA; patient IDs 4545, 4941, 5021, 5034, 5068, 5109, 5197, 5128, 5328-5346; available at http://ecaruca.radboudumc.nl:8080/ecaruca/) or to the DatabasE of genomiC varIation and Phenotype in Humans using Ensembl Resources (DECIPHER; patient IDs 264572, 359643, 359690, 359692, 359693, 360315; available at https://

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Processed on: 29-10-2018 PDF page: 170PDF page: 170PDF page: 170PDF page: 170 decipher.sanger.ac.uk/). Patients with PRRT2 sequence variants were submitted to the Leiden

Open Variation Database 2.0 (LOVD 2.0; patient IDs 151965, 153034, 153062, 153085, 153086, 153280, 153281, 153283-153287; available at http://www.lovd.nl/2.0).

Analysis and statistics

We used SPSS Statistics Version 23.0 (IBM Corporation, NY, USA). Descriptive statistics were applied to our data. To compare phenotypic diﬀerences between two patient cohorts, we used Fisher’s exact tests for categorical data and Mann-Whitney U tests for continuous variables. A p-value < 0.05 was considered signiﬁcant.

Ethics

A formal evaluation of the study was waived by the Medical Ethical Committee of UMC Groningen because of its observational character.

References

1 Fisher R. Operational Classiﬁcation of Seizure Types by the International League Against Epilepsy. J Chem Inf Model 2013; 53: 1689–99.

2 Fisher RS. The New Classiﬁcation of Seizures by the International League Against Epilepsy 2017. Curr. Neurol. Neurosci. Rep. 2017; 17: 48.

3 Scheffer IE, Berkovic S, Capovilla G, et al. ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology. Epilepsia 2017; 58: 512-521.

4 Bruno MK, Hallett M, Gwinn-Hardy K, et al. Clinical evaluation of idiopathic paroxysmal kinesigenic dyskinesia: new diagnostic criteria. Neurology 2004; 63: 2280–2287.

5 Headache Classiﬁcation Committee of the International Headache Society. The International Classiﬁcation of Headache Disorders, 3rd edition (beta version). Cephalalgia 2013;33:629–808.

6 World Health Organization. Obesity and overweight. 2016. Available at: http://www.who.int/mediacentre/factsheets/ fs311/en/ (accessed 1 Feb 2017).

7 Netherlands Organisation for Applied Scientiﬁc Research. Groeidiagrammen in PDF-format. 2010. Available at: https://www.tno.nl/nl/aandachtsgebieden/gezond-leven/prevention-work-health/gezond-en-veilig-opgroeien/ groeidiagrammen-in-pdf-formaat/. (accessed 1 Feb 2017).

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Supplemental Figure 1: 16p11.2 deletions including PRRT2 in our cohort.

The black bars represent the 16p11.2 deletions that include PRRT2 in the patients in our cohort (n=33). 16p11.2 deletion syndrome region is indicated by the blue zone. The chromosomal coordinates of 16p11.2 deletions were based on the Genome Reference Consortium Human Reference sequence version 37 (GRCh37/hg19).

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Supplemen tal T able 1: Genot ypes , phenot

ypes and family hist

or

ies of patients with a 16p11.2 deletion or a

PRRT2 sequence var iant Pt. S e x , a g e in y e ars G e not y p e Inhe ritance PR RT 2 -r el a ted phenot ype P ossib le PR RT 2 -re late d phenot ype Family histor y for e p ile p sy , mo v e me n t disorders or migr aine (re lat iv e does t h is re lat iv e share t h e same genot ype ) Re f 1 6 p 11 .2 de let ions (n = 3 3 ) D e n o v o 1 6 p 11 .2 d e le ti o n s ( n =22 ) 1M , 1 3 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 6 48 4_ 30 19 87 53 )x 1) D e nov o -Fo cal epileps y -2 F, 3 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2950 39 93 _ 30 195 35 6) x1 De n o vo BI E -3F , 1 5 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 62 0 489_ 30 19 950 7) x1 De n o vo BI E Myo clonic d ys tonia with c o rt ic al m yo cl o nus, h emip le gic migr ain e --5M , 1 4 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 47 78 59_ 30 19 950 7) x1 De n o vo -9M , 1 1 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 62 14 98 _ 30 26 40 61 )x 1 De n o vo -13 F, 7 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 6 48 4_ 30 19 74 90 )x 1 De n o vo -14 M , 7 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 656 48 4_ 30 19 950 7) x1 De n o vo -16 M , 1 2 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 729 6 _ 30 17 80 00 )x 1 D e novo -Migr ain e ( ma ter nal m o th er unlikel y )-21 M , 1 2 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 6 48 3_ 30 19 87 52 )x 1 De n o vo -24 M , 9 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 729 6 _ 30 177 91 7) x1 D e novo -M igr ain e M igr ain e (gr an dm o th er unlikel y) -25 M , 6 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 62 45 65 _ 30 19 875 3) x1 De n o vo -28 M , 1 0 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 24 88 _ 30 177 80 7)x 1 De n o vo -U n class iﬁe d epileps y ( si st er unlikel y) , Migr ai ne (f at h er n o , ma ter nal p ar en ts unlikel y) -29 M , 5 ar r[ G R Ch3 7 ] 16 p11 .2 (2 95 03 99 3_ 30 28 1111 )x 1 De n o vo -30 M , 1 3 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 7295 _ 30 17 8 40 6) x1 D e novo -Migr ain e ( m o th er no, ma ter n al p ar en ts unlikel y) -33 F, 2 1 † ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 41 85 _ 30 10 685 2) x1 D e novo Fo ca l epileps y -41 M , 8 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 43 22 12 _ 30 177 91 6) x1 D e novo -Migr ain e (gr an d m o th er unlikel y)

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-525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp 525699-L-sub01-bw-Vlaskamp Processed on: 29-10-2018 Processed on: 29-10-2018 Processed on: 29-10-2018

C ontinuation Supplemental Table 1 Pt. S e x , a g e in y e ars G e not y p e Inhe ritance PR RT 2 -re late d phenot ype P ossib le PR RT 2 -re late d phenot ype Family histor y for e p ile p sy , mo v e me n t disorders or migr aine (re lat iv e does t h is re lat iv e share th e same genot ype ) Re f 42 F, 2 9 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 7295 _ 30 177 99 9)x 1 De n o vo BI E -43 F, 3 0 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 729 6 _ 30 177 91 7) x1 De n o vo -46 F, 1 0 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 66 8 4_ 30 19 935 1) x1 D e novo -M igr ain e M igr ain e ( si st er unlikel y, p at er n al m o th er unlikel y) -47 F, 8 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 6 48 4_ 30 19 87 53 )x 1 D e novo -Migr ain e ( m o th er no )-54 F, 8 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 43 22 13 _ 30 177 91 7) x1 De n o vo -55 M , 8 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 729 6 _ 30 177 91 7) x1 D e novo -Migr ain e ( m o th er no) -Inher ite d 1 6 p 11 .2 de let ions (n = 6 ) 23 F, 22 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 34 59 03 _ 30 26 40 61 )x 1 Inh er ite d -BIE ( si st er yes ), Migr ain e ( si st er yes , p at er n al m o th er ? )-26 M , 1 1 ar r[ G R Ch3 7 ] 16 p11 .2 (2 95 03 99 3_ 30 28 1111 )x 1 Pa te rn al -M ig ra in e Mig ra ine (f at he r yes , p at er n al m o th er ?) -31 M , 3 7 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 67 32 03 _ 30 17 78 07 )x 1 Ma ter nal -32 F, 1 5 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 47 80 59 _ 30 19 93 51 )x 1 Pa te rnal -Pr o b ab le migr ain e -39 M , 1 2 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 62 14 98 _ 30 26 40 61 )x 1 Ma ter nal -50 F, 6 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2956 41 85 _ 30 10 685 2) x1 Pa te rnal -1 6 p 11 .2 de let ions wit h unk n o w n inher itanc e (n =5 ) 4M , 1 0 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2950 39 93 _ 30 195 35 6) x1 U nk n ow n -M igr ain e ( m o th er ?) -11 F, 2 1 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 65 6 48 4_ 30 19 87 53 )x 1 Un kn ow n -12 M , 2 0 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 656 48 4_ 30 19 950 7) x1 Un kn ow n -18 M , 2 1 ar r[ G R Ch3 7 ] 16 p1 1. 2( 29 62 06 88 _ 30 19 85 52 )x 1 No t m at ern al -Ep ileps y but no BIE ( m o th er no) Migr ain e ( m o th er no, ma ter n al m o th er unlikel y) -34 F, 1 5 ar r[ G R Ch3 7 ] 16 p1 1. 2( 2950 39 93 _ 30 195 35 6) x1 U nk n ow n -Poss ib ly epileps y ( m o th er ?, br o th er ?)

-

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C ontinuation Supplemental Table 1 Pt. S e x , a g e in y e ars G e not y p e Inhe ritance PR RT 2 -r el a ted phenot ype P ossib le PR RT 2 -re late d phenot ype Fa mily histor y for epilepsy , mo v e men t disorders or migr aine (r e lat iv e does t h is re lat iv e share t h e same genot ype ) Re f P R RT2 se quenc e var ian ts (n = 12 ) In h e ri te d PR R T 2 s e q u e n ce v a ri a n ts (n = 5 ) 10 F, 2 4 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Ma ter nal BF IE HM BF IE (br o th er yes ), H emip le g ic migr ain e ( m o th er yes ), Migr ain e (br o th er yes ) -20 F, 20 c. 82 4C > T; p .(S er 27 5P he *) Pa te rnal PK D -BF IE ( fa th er yes ), P K D ( two s ibs yes ), Migr ain e ( fa th er yes , thir d sib no) 1 35 F, 2 2 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Pa ter nal PK D /IC HM PK D ( fa th er yes , pa te rn al pa re n t yes ) 1 36 F, 5 c. 62 9dup; p. (Ala2 11 Ser fs *1 4) Ma te rnal BF IE -BF IE (br o th er ?, ma ter n al f ath er ? )-48 F, 48 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Inh er ite d BF IE H M BF IE ( thr ee s ibs ye s i n 1 , ? i n 2 , f ath er ?), H emip le gic migr ain e (t h re e s ib s ye s i n 2 , ? i n 1 , f ath er ?, pa te rn al pa re n t ?), M ig ra in e (t w o s ib s ye s i n 1 , ? i n 1 ) 2-4 P R RT2 se quenc e var ian ts wit h unk n o w n inher itanc e (n = 7 ) 6 M , 4 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) U nk n ow n BF IE -BF IE ( fa th er ?, s is ter ? )-7F , 3 1 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) U nk n ow n PK D U n class iﬁe d epileps y PK D ( si st er ?, m o th er ?, ma ter n al m o th er ? )-8M , 1 8 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Un kn ow n PK D -17 F, 1 3 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) U nk n ow n PK D /I C M igr ain e Migr ain e (f at h er ?, p at er nal p ar en ts ? )-44 M , 3 4 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Un kn ow n PK D -49 M , 2 4 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) U n kn o w n PKD -PKD (fa th er ?) -53 F, 1 8 c. 6 49 d u p C ; p. (A rg2 17Pro fs* 8) Un kn ow n PK D -? T h is relati ve ’s g en o ty p e is n o t k n ow n b ec aus e n o g en eti c t es tin g has b een p er fo rm ed . T h e chro m o so mal c o o rdinat es o f 1 6p 11 .2 d el eti o n s were b as ed o n th e G en o m e R eferen ce C o ns o rtium Human R eferen ce s equ en ce ver si o n 3 7 ( G R C h3 7/ h g1 9) . PR RT 2 va ri an ts w er e r ep o rt ed i n a cc o rd an ce w it h t h e t ra n sc ri p t v ar ia n t 1 o f PR RT 2 (N M _1 45 23 9. 2) . A b b re vi at io n s: B FI E b en ig n f am ili al inf an til e ep ileps y, B IE b eni gn inf an til e ep ileps y, HM h emip le g ic mi gr ain e, NM O -h ea d ach e n o t-m edi ca ti o n -over u se h ea d ach e, P K D p arox ysmal k in esi g eni c d ysk in es ia , T TH t ensi o n -t yp e he ad ac he . Re fe re nc es 1. v an V lie t R , B re e d ve ld G , d e R ijk -v an A n d e l J , e t a l. P R R T 2 p h e n ot yp e s a n d p e n e tr an ce o f p arox ysm al k in e si g e ni c d ysk in e sia a n d in fa nt ile c o n v u lsi o n s. N e u ro lo g y. 20 12 ; 7 9 : 777 -7 8 4 . 2. C all e n b a ch P , D e C o o R FM , V e in A A , e t a l. B e ni g n f am ilia l in fa nt ile c o n v u lsi o ns: A clini ca l s tu d y o f s e ve n D u tc h f am ili e s. Eu r J Pa e d iat r N e u ro l. 20 0 2; 6: 2 6 9 -2 8 3. 3. V anm o lkot K R J, Ko rs EE , H ot te n g a J , e t a l. N o ve l mu ta ti o ns in t h e N a+ , K + -A T P as e p u m p g e n e A T P 1A 2 ass o ciat e d w it h f am ilia l h emip le gic migr ain e an d b e nign f amilial inf an til e c o n v ul si o n s. A n n N e u ro l. 20 0 3 ; 5 4 : 36 0 -36 6 4. P e lz e r N , d e V ri e s B, K am p h o rs t J T, e t a l. P R R T 2 a n d h e m ip le g ic m ig ra in e : A c o m p le x ass o ciat io n . N e u ro lo g y. 20 14 ; 8 3 : 2 8 8 -2 90 .

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Supplemental Table 2: Migraine in patients with a 16p11.2 deletion and a PRRT2 sequence variant

Pt Sex, Age in

years Migraine diagnosis Aura

Motor weakness

Number of days missing school or work / social activities (in last 3 months) 16p11.2 deletions (n=5) 3 F, 15 Hemiplegic migraine Visual, sensitive, speech Yes 0 / 0

24 M, 9 Migraine without aura No No 0 / 0

26 M, 11 Migraine without aura No No 0 / 0

32 F, 15 Probable migraine without aura No No 0 / 0

46 F, 10 Migraine without aura Unknown No 2 - 4

PRRT2 sequence variants (n=4)

10 F, 24 Hemiplegic migraine Visual, _sensitive Yes 1 / unknown

17 F, 13 Migraine with aura Visual, _sensitive No 0 / 0

35 F, 22 Hemiplegic migraine1,2 _Speech _? _{0 / 0}

48 F, 48 Hemiplegic migraine1,3 Visual,

speech Yes 0 / 0

1 _{Hemiplegic migraine did not cosegregate with PRRT2 sequence variants in these patients’ families (1-4).}2_{A paternal sibling}

had hemiplegic migraine but no PRRT2 variant (1). 3 _{A causal ATP1A12 sequence variant for hemiplegic migraine was identiﬁed}

in this patient and her relatives (3-4).

References

1. van Vliet R, Breedveld G, de Rijk-van Andel J, et al. PRRT2 phenotypes and penetrance of paroxysmal kinesigenic dyskinesia and infantile convulsions. Neurology. 2012; 79: 777-784.

2. Callenbach P, De Coo RFM, Vein AA, et al. Benign familial infantile convulsions: A clinical study of seven Dutch families. Eur J Paediatr Neurol. 2002; 6: 269-283.

3. Vanmolkot KRJ, Kors EE, Hottenga J, et al. Novel mutations in the Na+, K+-ATPase pump gene ATP1A2 associated with familial hemiplegic migraine and benign familial infantile convulsions. Ann Neurol. 2003; 54: 360-366.

4. Pelzer N, de Vries B, Kamphorst JT, et al. PRRT2 and hemiplegic migraine: A complex association. Neurology. 2014; 83: 288-290.

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University of Groningen Genotyping and phenotyping epilepsies of childhood Vlaskamp, Danique

Genotyping and phenotyping epilepsies of childhood

Vlaskamp, Danique

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PRRT2-related phenotypes in patients

with a 16p11.2 deletion

ABSTRACT

INTRODUCTION

METHODS

RESULTS

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DISCUSSION

CONCLUSION

WEB RESOURCES

REFERENCES

SUPPLEMENTAL DATA

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