Deep Intronic FGF14 GAA Repeat Expansion in Late-Onset Cerebellar Ataxia

To the Editor: Pellerin et al. (Jan. 12 issue)(1) reported a dominant FGF14 GAA repeat expansion in persons with late-onset cerebellar ataxia. They also identified persons who were homozygous or compound heterozygous for expansions of at least 250 GAA repeats ([GAA](>= 250)), a finding consistent with the possibility of codominance at this locus (with both alleles expressed simultaneously). Here, we report two siblings with early-onset cerebellar ataxia from a consanguineous Chinese family who carried biallelic FGF14 GAA repeat expansions. One of the siblings initially had episodic gait imbalance at 21 years of age; progressive dysarthria, postural tremor, spasticity, and downbeat nystagmus . . .

Automated summary

Pellerin et al. reported a dominant FGF14 GAA repeat expansion in individuals with late-onset cerebellar ataxia. They also identified individuals who were homozygous or compound heterozygous for expansions of at least 250 GAA repeats (GAA>=250), suggesting codominance at this locus. Here, we present two siblings from a consanguineous Chinese family with early-onset cerebellar ataxia who carried biallelic FGF14 GAA repeat expansions. One sibling initially presented with episodic gait imbalance at 21 years of age and subsequently developed progressive dysarthria, postural tremor, spasticity, and downbeat nystagmus...