Our data indicate SYNE1 mutations are not an uncommon cause of recessive ataxia with or without additional clinical features in patients from various ethnicities.
Here, we report a newly discovered form of recessive ataxia in a French-Canadian cohort and show that SYNE1 mutations are causative in all of our kindreds, making SYNE1 the first identified gene responsible for a recessively inherited pure cerebellar ataxia.
There is a SYNE1 genotype-phenotype correlation emerging, with more proximal homozygous SYNE1 variants causing recessive cerebellar ataxia of variable onset (SCAR8; ARCA-1).
Our findings support a genotype-phenotype correlation in SYNE1-ataxia and suggest the need for a systematic cardiologic evaluation in the setting of complicated spastic-ataxia phenotypes.
Nevertheless, recent studies on SYNE1ataxia have conveyed the condition from a geographically limited pure cerebellar recessive ataxia to a complex multisystem phenotype that is relatively common on the global scale.
Here, we report a newly discovered form of recessive ataxia in a French-Canadian cohort and show that SYNE1 mutations are causative in all of our kindreds, making SYNE1 the first identified gene responsible for a recessively inherited pure cerebellar ataxia.
In the ataxia group, we found (CAG)n above the range of the asymptomatic blood donors in SCA3 (21.74%) followed by SCA2 (5.22%), SCA7 (2.61%), SCA6 (0.87%), and no cases of SCA1.
We investigated the (CAG)n repeat length of the CACNL1A4 gene in 733 patients with sporadic ataxia and in 46 German families with dominantly inherited SCA which do not harbor the SCA1, SCA2, or MJD1/SCA3 mutation, respectively.
This late-onset paroxysmal cerebellar ataxia with neuropathological lesions restricted to Purkinje cells and with negative results both for truncating mutations and CAG expansion in the CACNA1A gene represents a new entity.
Mutations at the mouse orthologue of the CACNA1A gene cause a group of recessive neurological disorders, including the tottering, leaner, and rocker phenotypes with ataxia and absence epilepsy, and the rolling Nagoya phenotype with ataxia without seizures.
Autosomal dominant mutations in the CACNA1A gene, which encodes voltage-gated P/Q-type calcium channel subunit α(1) (the principal pore-forming subunit of the P/Q channel) are associated with episodic and progressive forms of cerebellar ataxia, familial hemiplegic migraine, vertigo and epilepsy.
Here, we explored the effects of G protein-dependent modulation on mutations W1684R and V1696I which cause FHM-1 with and without cerebellar ataxia, respectively.
In over 50% of cases the causative gene is CACNA1A (FHM1), which in some cases produces a phenotype with cerebellar signs, including ataxia and nystagmus.
DNA sequencing and gene expression data demonstrate that Cacnl1a4 mutations are the primary cause of seizures and ataxia in tottering and leaner mutant mice, and suggest that tottering locus mutations and human diseases, episodic ataxia 2 and familial hemiplegic migraine, represent mutations in mouse and human versions of the same channel-encoding gene.
Methods Eight patients from a multigenerational FHM type 1 family harbouring a T666M mutation in the CACNA1A gene were referred to our ataxia outpatient clinic.