Referenced in: none

Automatically associated channels: Cav2.1

Title: Infantile nystagmus and late onset ataxia associated with a CACNA1A mutation in the intracellular loop between s4 and s5 of domain 3.

Authors: J Self, C Mercer, E M J Boon, M Murugavel, F Shawkat, S Hammans, P Hodgkins, H Griffiths, A Lotery

Journal, date & volume: Eye (Lond), 2009 Dec , 23, 2251-5

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19182766

Abstract
Mutations in the 1A-subunit of the brain P/Q-type calcium channel gene CACNA1A are responsible for spinocerebellar ataxia type 6 (SCA6), familial haemiplegic migraine (FHM) and episodic ataxia type 2 (EA2). Considerable clinical and genetic overlap exists between these 3 allelic disorders. Clinical findings are varied and may include nystagmus.To study the clinical phenotype and identify a causative mutation in a family who presented when the youngest member was diagnosed with apparent isolated congenital nystagmus (age 3 months).8 patients from one family underwent detailed clinical phenotyping comprising; ophthalmic and neurological examination, nystagmology, electrodiagnostic tests and brain imaging. The CACNA1A gene was screened for mutations by direct sequencing in one patient. Co-segregation of the disease and an identified sequence variation was shown using direct sequencing.Phenotyping revealed isolated atypical nystagmus in 4 family members and nystagmus in addition to late onset ataxia in 1 family member. Direct sequencing of the CACNA1A gene identified a novel missense mutation; (c.4110T>G p.Phe1370Leu (NM_000068.3)).We have shown that a mutation in the intracellular domain between s4 and s5 of repeat 3 can cause atypical nystagmus/cerebellar phenotypes, including isolated nystagmus in an infant. We also illustrate the necessity for detailed examination of relatives in cases of apparent isolated congenital nystagmus.