Here I present: “Episodic Ataxia”, Victor McKusick, Mendelian Inheritance in Man’, 1966. (EA9) 偶共共济失调。
INTRODUCTION.
Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements, that indicates dysfunction of parts of the nervous system that coordinate movement (cerebellum).
Episodic ataxia (EA) is an autosomal dominant disorder characterized by sporadic bouts of ataxia (severe discoordination) with or without myokymia (continuous muscle movement). There are seven (7) types recognized but the majority are due to two recognized entities. Ataxia can be provoked by psychological stress or startle, or heavy exertion, including exercise. Symptoms can first appear in infancy. There are at least six (6) loci for EA, of which four (4) are known genes. Some patients with EA also have migraine or progressive cerebellar degenerative disorders, symptomatic of either familial hemiplegic migraine or spinocerebellar ataxia.
There is evidence that episodic ataxia type-9 (EA9) is caused by heterozygous mutation in the SCN2A gene on cytogenetic location 2q24.3 and genomic coordinates 2:165,239,414-165,392,304 . The screenshot of the SCN2A gene 152,891 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides SCN2A in the 2q24.3 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name. |
| 2:164,492,417 | GRB14 | Growth factor receptor-bound protein 14 |
| 2:164,657,931 | COBLL1 | COBL-like protein 1 |
| 2:164,894,354 | SLC38A11 | Solute carrier family 38 member 11 |
| 2:165,087,526 | SCN3A | Sodium voltage-gate channel alpha 3 |
| 2:165,239,414 | SCN2A | Sodium voltage-gate channel alpha 2 |
| 2:165,469,698 | CSRNP3 | Cysteine- and serine-rich nuclear protein 3 |
| 2:165,747,588 | GALNT3 | GalNAc transferase 3 |
| 2:165,873,362 | TTC21B | Tetratricopeptide repeat domain 21B |
| 2:165,984,641 | SCN1A |
Sodium voltage-gate channel alpha 1 |
| 2:166,195,185 | SCN9A | Sodium voltage-gate channel alpha 9 |
