Novel PNKP mutation in siblings with ataxia-oculomotor apraxia type 4

Nicoline Schiess, David S. Zee, Khurram A. Siddiqui, Miklos Szolics, Ayman W. El-Hattab

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The phenotypic and genetic spectrum of ataxia with oculomotor apraxia (AOA) disorders is rapidly evolving and new technologies such as genetic mapping using whole exome sequencing reveal subtle distinctions among the various subtypes. We report a novel PNKP mutation in two siblings with progressive ataxia, abnormal saccades, sensorimotor neuropathy and dystonia consistent with the AOA type 4 phenotype. Laboratory evaluation revealed hypoalbuminemia, hypercholesterolemia with elevated LDL, elevated IgE levels and normal α fetoprotein levels. Eye movement examination demonstrated a marked saccade initiation defect with profound hypometric horizontal saccades. Vertical saccades were also affected but less so. Also present were conspicuous thrusting head movements when attempting to change gaze, but rather than an apraxia these were an adaptive strategy to take advantage of an intact vestibulo-ocular reflex to carry the eyes to a new target of interest. This is demonstrated in accompanying videos.

Original languageEnglish (US)
Pages (from-to)23-25
Number of pages3
JournalJournal of Neurogenetics
Issue number1-2
StatePublished - Apr 3 2017


  • AOA type 4
  • Ataxia
  • PNKP
  • oculomotor apraxia
  • saccades

ASJC Scopus subject areas

  • Genetics
  • Cellular and Molecular Neuroscience


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