Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia as a Presentation of a Novel DNMT1 Mutation.

A 50-year-old woman with a 20-year history of gait instability presented with new-onset vertigo and oscillopsia. Examination revealed bilateral vestibular loss, cerebellar ataxia, sensory neuropathy, a "yes-yes" head tremor, nystagmus and a family history of a similar syndrome. Genetic testing for cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (RFC1) was negative, but whole exome sequencing identified a novel mutation in the DNA methyltransferase 1 (DNMT1) gene, broadening the differential diagnosis for this phenotype. Management was focused on symptomatic treatment and genetic counseling. This case highlights the importance of considering DNMT1 mutations in patients with a similar clinical presentation.