Table 2.
Genetic diagnosis and phenotype in 9 non-familial cases
| Case # (gender) | Gene (Ref Seq) | Genetic variant | Inheritance | Seizures, type | Age of onset, months | Phenotype | EEG data | Brain MRI |
|---|---|---|---|---|---|---|---|---|
| 6 (m) | CASK (NM_001367721.1) |
c.2301T>G c.2300T>G (p.Phe767Gly) |
XLD/XLR, hemizygous | Generalized, tonic | 6 | PMD, EE | Diffuse, bilateral-synchronous and asynchronous peak/spike-slow wave complexes | Diffuse changes in the white matter of the cerebral hemisphere (post-hypoxic genesis), mixed hydrocephalus, retrocerebellar cyst, cyst of the right choroidal fissure |
| 7 (f) | SLC2A1 (NM_006516.4) | c.988C>T (p.Arg330*) | AD, heterozygous | Generalized, clonic-tonic | 3 | PMD, SD, EE, microcephaly | Central leads, spike-slow wave complexes | Diffuse changes in the white matter of the cerebral hemisphere |
| 8 (m) | ARX (NM_139058.3) | c.1612A>G (p.Lys538Glu) | XLR, hemizygous | Polymorphic | 6 | PMD, SD, microcephaly, hypotony | Low-amplitude hypsarrhythmia — constant multifocal, asynchronous, epileptiform activity in the form of spike-slow wave complexes with a focus in the frontal, separately in the temporal and central leads | Post-hypoxic changes in the cerebral hemispheres, mixed hydrocephalus |
| 9 (f) | MT-CO3 | c.172G>A (p.Trp58*) | Mi, homoplasmy | Generalized, tonic | 1 | PMD, SD, acidosis, excess subcutaneous fat | Grouped complexes of a spike-slow wave in the frontal leads with spread to the middle-temporal leads bilaterally | Symmetrical focal changes in the structure of the thalamus of a metabolic/neurodegenerative nature (Leigh syndrome), moderate combined hydrocephalus, retrocerebellar cyst |
| 10 (f) | GRIN2D (NM_000836.4) | c.3550G>A (p.Ala1184Thr) | AD, heterozygous | Polimorphic | 7.5 | SD | Lateralized to the right leads diffuse rhythmic theta-like wave with the beginning in the parietal and temporal leads gradually turning into low-frequency delta waves and spreading to the left parts of the brain | Cysts of the septum pellucidum |
| 11 (f) | KCNT1 (NM_020822.3) | c.1421G>A (p.Arg474His) | AD, heterozygous | Clonic-tonic | 1 | PMD, SD, resistance to fenobarbital, carbamazepine | Rhythmic beta/alpha-like waves in the right occipital and separately in some seizures in the right temporal leads, with diffuse propagation, gradually turning into theta waves | Post-hypoxic changes in the white matter of the cerebral hemispheres, moderate external hydrocephalus |
| 12 (m) | CHRNA2 (NM_000742.4) | c.612G>A (p.Trp204*) | AD, heterozygous | Focal, clonic | Infancy | SD, status epilepticus, resistance to fenobarbital | Bursts of delta waves with a maximum amplitude in the central and temporal leads | Subatrophy of the cerebral hemispheres, bilateral convexital subdural hygroma more pronounced on the right |
| 13 (f) | SCN1A (NM_001165963.4) | c.3706-2A>C (Splice acceptor) | AD, heterozygous | Focal, clonic | 7 | PMD, SD | Continued deceleration in the right frontal leads | Intracranial hypertension |
| 14 (m) | SCN1A (NM_001165963.4) | c.3982T>C (p.Ser1328Pro) | AD, heterozygous | Focal, clonic | 4 | Resistance to levetiracetam | An increase in the index of diffuse slow delta waves, single sharp waves were also recorded in the occipital, separately in the frontal leads | - |
Note: AD, autosomal dominant; XLD, X-linked dominant; XL, XLR, X-linked recessive; Mi, mitochondrial; PMD, psychomotor delay; SD, speech delay; EE, epileptic encephalopathy; m, male; f, female