Childhood-onset ataxia with dystonia: expanding the spectrum of VWA3B-related disorders.

Hereditary cerebellar ataxias are a group of rare genetic disorders that affect coordination, balance, and speech. Childhood-onset forms can be especially severe and difficult to diagnose. The VWA3B gene, though not fully understood, plays a role in brain development and has been linked to autosomal recessive spinocerebellar ataxia type 22 (SCAR22), an adult-onset cerebellar ataxia with variable features. A single family with 3 affected adults has been described to date. We report a 1 year 9 months old boy with early-onset neuroregression and ataxia. Prominent dystonia involving the limbs and eyelids (blepharospasm) was also a novel feature observed in him. Exome sequencing revealed compound heterozygous variants in VWA3B. Unlike the previous report describing a missense variant, our patient had nonsense and frameshift variants. This case highlights the expanding clinical and genotypic spectrum of VWA3B-related ataxia.