Expanding the ataxia with oculomotor apraxia type 4 phenotype

Ataxia with oculomotor apraxia type 4 (AOA4) is an autosomal recessive (AR) disorder recently delineated in a Portuguese cohort and caused by mutations in the PNKP (polynucleotide kinase 3′-phosphatase) gene. AOA4 is a progressive, complex movement disorder that includes hyperkinetic features, eye movement abnormalities, polyneuropathy, varying degrees of cognitive impairment, and obesity. PNKP mutations were initially discovered to be the cause of the severe nonprogressive syndrome microcephaly, early-onset intractable seizures, and developmental delay (MCSZ). Here we describe a patient with compound heterozygous PNKP mutations presenting with an AOA4 phenotype. New features that we report include both mutations, presence of chorea, absence of oculomotor apraxia (OMA), and slow disease progression.