A New Phenotype of Ataxia With Oculomotor Apraxia Type 4

Ataxia with oculomotor apraxia is a rare neurodegenerative subgroup of diseases with manifestations that include cerebellar ataxia, oculomotor apraxia, extrapyramidal features, and sensorimotor neuropathy. In 2015, ataxia with oculomotor apraxia type 4 was described in 11 Portuguese individuals. The mean age of onset was 4.3 years, with severe extrapyramidal manifestations, neuropathy, rapid progression, and ataxia, being wheelchair-bound during adolescence. The disease is caused by homozygous or compound heterozygous mutations in the PNKP gene. In this case report, we describe two sisters, who were 52- and 58-years-old, with cerebellar dysarthria, oculomotor apraxia, dystonia, and gait ataxia. Two new mutations in the PNKP gene were detected in both sisters, confirming the diagnosis of ataxia with oculomotor apraxia. They were remarkable because they were able to walk unaided during adulthood and had epilepsy. With these clinical cases, we attempt to raise awareness of the possibility of different phenotypes of this rare disease, expanding the spectrum of manifestations of ataxia with oculomotor apraxia type 4.