Table 1. Overview of the SCN1A mutations identified in patients with epilepsy (# cases)

Mutation

SME

EE

PE & PEFS+

GE and/or FS

Unclassified

Unknown

Total (%)

SMEI

SME(U)

SMEB

 

PE

PEFS+

GE

GEFS+

FS+/FS

Point mutations

 

 

 

 

 

 

 

 

 

 

 

Missense

397

130

85

59

13

25

7

49

11

13

7

796 (46.1)

In-frame delection

14

4

5

1

0

0

0

0

0

0

0

24 (1.4)

compound mutation

5

0

1

0

0

0

0

0

0

0

0

6 (0.3)

Start codon mutation

2

0

0

0

0

0

0

0

0

0

0

2 (0.1)

Splice site

108

24

9

11

2

2

1

4

0

4

4

169 (9.8)

Nonsense

204

55

25

10

0

1

0

2

1

2

3

303 (17.5)

Frameshift

214

49

26

17

2

3

0

0

0

3

1

315 (18.2)

3‘UTR mutation

1

0

0

0

0

0

0

0

0

0

0

1 (0.1)

synonymous

0

1

0

0

1

0

0

0

1

0

0

3 (0.2)

Subtotal

945

263

151

98

18

31

8

55

13

22

15

1619 (93.7)

Genomic rearrangements

 

 

 

 

 

 

 

 

 

 

Partial genomic rearrangement

56

14

3

2

1

0

1

0

0

1

2

80 (4.6)

whole gene deletion

11

5

0

4

0

0

0

0

0

3

0

23 (1.3)

whole gene duplication

0

0

0

0

0

0

0

0

0

5

0

5 (0.3)

Subtotal

67

19

3

6

1

0

1

0

0

9

2

108 (6.3)

Total (%)

1012(58.6)

282 (16.3)

154 (8.9)

104 (6.0)

19 (1.1)

31 (1.8)

9 (0.5)

55 (3.2)

13 (0.8)

31 (1.8)

17 (1.0)

1727

Legend:

SMEI: severe myoclonic epilepsy of infancy or classical Dravet syndrome (DS). SMEB: SMEI borderline, which also included intractable childhood epilepsy with generalized tonic-clonic seizures (ICEGTC) and incomplete Dravet syndrome (IDS). SME (U): indicated the phenotype that was diagnosed to Dravet syndrome in the original articles, but lacked of sufficient clinical information to further classify into SMEI or SMEB. EE: epileptic encephalopathy, which included acute necrotizing encephalopathy (ANE), acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), classical Dravet syndrome like or SMEI-like (DS-like), early onset epileptic encephalopathies (EOEE), epilepsy-aphasia, epilepsy-aphasia with febrile seizure plus, hemiconvulsions hemiplegia epilepsy (HHE), intractable epilepsy (IE), infantile spasms (IS), Lennox-Gastaut syndrome (LGS), LGS (late-onset), myoclonic astatic epilepsy (MAE), malignant migrating partial seizures in infancy (MMPSI), progressive myoclonic epilepsy (PME ), Rasmussen encephalitis (RE), severe idiopathic generalized epilepsy of infancy (SIGEI), and severe infantile multifocal epilepsy (SIMFE). PEFS+: partial epilepsy and febrile seizures plus, which also included cryptogenic focal epilepsy with febrile seizures (CFE&FS), temporal lobe epilepsy with febrile seizures (FS&TLE), and atypical multifocal DS lacks generalized seizures. PE: partial epilepsy, which included autosomal dominant nocturnal frontal lobe epilepsy (ANDFLE), acute encephalitis with refractory, repetitive partial seizures (AERRPS), cryptogenic focal epilepsy (CFE), familial hemiplegic migraine with benign occipital epilepsy (FHM+BOE), familial hemiplegic migraine with epilepsy (FHM+EP), focal epilepsy with malformations of cortical development (FE&MCDs), and Panayiotopoulos syndrome (PS). GE: generalized epilepsy, which included cryptogenic generalized epilepsy (CGE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and symptomatic generalized epilepsy (SGE). FS: febrile seizures. FS+: febrile seizures plus, cryptogenic generalized epilepsy with febrile seizures (CGE&FS) was also included. Partial genomic rearrangement included partial gene duplication/deletion and translocation. Whole gene duplication also included whole gene amplification.