Summary of the 71 mutation-positive cases
| Case | Gene | Mutation | Inheritance | Gender | Diagnosis at referral for testing | Seizures |
|---|---|---|---|---|---|---|
| 1* | ATP1A3 | het c.958G>A; p.(Ala320Thr) | De novo | M | Possible ATP1A3-related disorder | Yes |
| 2 | ATP1A3 | het c.2839G>A; p.(Gly947Arg) | Not in mother | M | Developmental delay with seizures | Yes |
| 3 | CDKL5 | hemi c.532C>T; p.(Arg178Trp) | De novo | M | EIEE | Yes |
| 4 | CDKL5 | hemi c.2152G>A; p.(Val718Met) | Unknown | M | EIEE | Yes |
| 5 | CDKL5 | hemi c.2177_2186delinsAATGTGTCAAC; p.(Ser726*) | De novo | M | EIEE | Yes |
| 6 | CDKL5 | het duplication exons 6–11 | De novo | F | EIEE | Yes |
| 7 | CDKL5 | het c.167_168del; p.(Thr56Asnfs*6) | De novo | F | EIEE | Yes |
| 8 | CDKL5 | het c.965del; p.(Thr322Asnfs*28) | Unknown | F | EIEE | Yes |
| 9 | EHMT1 | het c.1596del; p.(Thr533Profs*30) | De novo | M | Developmental delay with seizures | Yes |
| 10 | FOXG1 | het c.256dup; p.(Gln86Profs*35) | Unknown | M | EIEE | Yes |
| 11 | FOXG1 | het c.572T>G; p.(Met191Arg) | From mosaic mother | M | Developmental delay with seizures | Yes |
| 12 | FOXG1 | het c.651C>G; p.(Tyr217*) | De novo | F | Developmental delay | No |
| 13 | FOXG1 | het c.695A>G ; p.(Asn232Ser) | De novo | M | Developmental delay with movement disorder | No |
| 14 | FOXG1 | het c.1188C>A; p.(Cys396*) | De novo | M | Developmental delay with movement disorder | No |
| 15 | GABRB3 | het c.860C>T; p.(Thr287Ile) | De novo | M | EIEE | Yes |
| 16 | KCNQ2 | het c.601C>T; p.(Arg201Cys) | Unknown | F | EIEE | Yes |
| 17 | KCNQ2 | het c.637C>T; p.(Arg213Trp) | Unknown | F | EIEE | Yes |
| 18 | KCNQ2 | het c.638G>A; p.(Arg213Gln) | Unknown | M | EIEE | Yes |
| 19 | KCNQ2 | het c.1681C>T; p.(Pro561Ser) | De novo | M | EIEE | Yes |
| 20* | KCNQ2 | het c.1741C>T; p.(Arg581*) | From father | M | Neonatal seizures | Yes |
| 21* | KCNQ2 | het c.1741C>T; p.(Arg581*) | From mother | M | Neonatal seizures | Yes |
| 22 | KCNT1 | het c.862G>A; p.(Gly288Ser) | Unknown | M | Developmental delay with seizures | Yes |
| 23 | KCNT1 | het c.2687T>A; p.(Met896Lys) | De novo | F | EIEE | Yes |
| 24* | KCNT1 | het c.2800G>A; p.(Ala934Thr) | De novo | M | EIMFS | Yes |
| 25 | LGI1 | het c.1A>G p.(Met1?) | Unknown | M | EIEE | Yes |
| 26 | MBD5 | het del chr2:149219863–149796844 including MBD5, EPC2, KIF5C | De novo | M | Developmental delay | Yes |
| 27* | MECP2 | het exon 4 deletion | De novo | F | Rett syndrome | Yes |
| 28* | MECP2 | het c.62+2_62+3del | Unknown | F | Possible Rett syndrome | No |
| 29 | MECP2 | het c.844C>T; p.(Arg282*) | Unknown | F | Developmental delay with seizures | Yes |
| 30* | MECP2 | het c.952C>T; p.(Arg318Cys) | De novo | F | Rett syndrome | No |
| 31 | MECP2 | het c.1119_1147del; p.(Lys375Leufs*20) | Unknown | F | Developmental delay with seizures | Yes |
| 32 | PIGA | het c.1064T>C; p.(Leu355Ser) | De novo | M | EIEE | Yes |
| 33 | PCDH19 | het c.688G>A; p.(Asp230Asn) | De novo | F | EIEE | Yes |
| 34 | PCDH19 | het c.707C>T; p.(Pro236Leu) | De novo | F | EIEE | Yes |
| 35 | PCDH19 | het c.1882dup; p.(Arg628Profs*12) | De novo | F | EIEE | Yes |
| 36* | PRRT2 | het c.649dup; p.(Arg217Profs*8) | Unknown | M | Kinesogenic dyskinesia | No |
| 37 | PRRT2 | het c.1021T>C; p.(*341Argext*28) | Unknown | F | Infantile seizure disorder | Yes |
| 38 | SCN1A | het c.302G>A; p.(Arg101Gln) | De novo | M | EIEE | Yes |
| 39* | SCN1A | het c.2589+1_2589+2dup | De novo | M | Dravet syndrome | Yes |
| 40 | SCN1A | het c.3851G>A; p.(Trp1284*) | Unknown | M | Developmental delay with seizures | Yes |
| 41 | SCN1A | het c.4034C>T; p.(Pro1345Leu) | De novo | F | EIMFS | Yes |
| 42 | SCN1A | het c.5010_5013del; p.(Phe1671Thrfs*8) | De novo | F | EIEE | Yes |
| 43 | SCN2A | het c.2619C>G; p.(Ile873Met) | De novo | F | EIEE with movement disorder | Yes |
| 44 | SCN2A | het c.2960G>T; (p.Ser987Ile) | De novo | F | EIEE | Yes |
| 45 | SCN2A | het c.2995G>A; p.(Glu999Lys) | De novo | M | EIEE | Yes |
| 46 | SCN2A | het c.2996A>T; p.(Glu999Val) | De novo | F | EIEE | Yes |
| 47 | SCN2A | het c.3778A>G; p.(Lys1260Glu) and c.3778A>C; p.(Lys1260Gln) mosaic | De novo | M | EIEE | Yes |
| 48 | SCN2A | het c.4303C>T; p.(Arg1435*) | De novo | M | Autism with seizures | Yes |
| 49 | SCN2A | het c.4436A>C; p.(Gln1479Pro) | De novo | M | EIEE | Yes |
| 50 | SCN2A | het c.4949T>C; p.(Leu1650Pro) | De novo | M | EIEE | Yes |
| 51 | SCN2A | het c.5485C>T; p.(Leu1829Phe) | De novo | M | EIEE | Yes |
| 52 | SCN2A | het c.5645G>A; p.(Arg1882Gln) | De novo | M | EIEE | Yes |
| 53 | SCN2A | het c.5645G>A; p.(Arg1882Gln) | De novo | M | EIEE | Yes |
| 54 | SCN8A | het c.1222G>A; p.(Ala408Thr) | De novo | M | EIEE with movement disorder | Yes |
| 55 | SCN8A | het c.3943C>G; p.(Val1315Met) | De novo | F | EIEE | Yes |
| 56 | SCN8A | het c.3967G>T; p.(Ala1323Ser) | De novo | M | EIEE | Yes |
| 57 | SCN8A | het c.3979A>G; p.(Ile1327Val) | De novo | M | EIEE | Yes |
| 58 | SCN8A | het c.5261T>C; p.(Phe1754Ser) | De novo | M | EIEE | Yes |
| 59 | SCN8A | het c.5594T>C; p.(Leu1865Pro) | De novo | F | EIEE | Yes |
| 60 | SLC9A6 | hemi c.608del p.(His203Leufs*10) | De novo | M | Developmental delay with seizures and movement disorder | Yes |
| 61 | SLC9A6 | hemi c.1222_1226del; p.(His408Asnfs*2) | De novo | M | EIEE | Yes |
| 62 | STXBP1 | het c.37+1G>A | De novo | F | EIEE | Yes |
| 63 | STXBP1 | het c.842T>C; p.(Leu281Pro) | De novo | F | Developmental delay with seizures | Yes |
| 64 | STXBP1 | het c.875G>A; p.(Arg292His) | De novo | M | EIEE | Yes |
| 65 | STXBP1 | het c.1019_1020del; p.(Glu340Alafs*12) | Unknown | M | Neonatal seizures including infantile spasms | Yes |
| 66 | STXBP1 | het c.1249+1G>T | Unknown | F | EIEE | Yes |
| 67 | TCF4 | het c.826C>T; p.(Arg276*) | De novo | F | Developmental delay | No |
| 68* | TCF4 | het c.1065C>G; p.(Se355Arg) | De novo | F | Pitt–Hopkins syndrome | No |
| 69 | TCF4 | het c.1296+1G>T | De novo | M | Developmental delay | No |
| 70 | UBE3A | het c.2572_2576dup; p.(Lys859Asnfs*7) | Unknown | F | Developmental delay | No |
| 71* | ZEB2 | het c.2083C>T; p.(Arg695*) | De novo | M | Mowat–Wilson syndrome | No |
*Cases in which referring clinician correctly nominated the causative gene at referral for testing.
EIEE, early infantile epileptic encephalopathy; EIMFS, epilepsy of infancy with migrating focal seizures; F, female; M, male.