Investigating neurological deficits in carriers and affected patients with ornithine transcarbamylase deficiency

Courtney Sprouse, Jessica King, Guy Helman, Ileana Pacheco-Colón, Kyle Shattuck, Andrew Breeden, Rebecca Seltzer, John W. Van Meter, Andrea L. Gropman

Research output: Contribution to journalArticle

Abstract

Background: Urea cycle disorders are caused by dysfunction in any of the six enzymes and two transport proteins involved in urea biosynthesis. Our study focuses on ornithine transcarbamylase deficiency (OTCD), an X-linked disorder that results in a dysfunctional mitochondrial enzyme, which prevents the synthesis of citrulline from carbamoyl phosphate and ornithine. This enzyme deficiency can lead to hyperammonemic episodes and severe cerebral edema. The objective of this study was to use a cognitive battery to expose the cognitive deficits in asymptomatic carriers of OTCD. Materials and methods:: In total, 81 participants were recruited as part of a larger urea cycle disorder imaging consortium study. There were 25 symptomatic participants (18 female, 7 male, 25.6. years ± 12.72 years), 20 asymptomatic participants (20 female, 0 male, 37.6. years ± 15.19 years), and 36 healthy control participants (21 female, 15 male, 29.8. years ± 13.39 years). All participants gave informed consent to participate and were then given neurocognitive batteries with standard scores and T scores recorded. Results:: When stratified by symptomatic participant, asymptomatic carrier, and control, the results showed significant differences in measures of executive function (e.g. CTMT and Stroop) and motor ability (Purdue Assembly) between all groups tested. Simple attention, academic measures, language and non-verbal motor abilities showed no significant differences between asymptomatic carriers and control participants, however, there were significant differences between symptomatic and control participant performance in these measures. Conclusions:: In our study, asymptomatic carriers of OTCD showed no significant differences in cognitive function compared to control participants until they were cognitively challenged with fine motor tasks, measures of executive function, and measures of cognitive flexibility. This suggests that cognitive dysfunction is best measurable in asymptomatic carriers after they are cognitively challenged.

Original languageEnglish (US)
Pages (from-to)136-141
Number of pages6
JournalMolecular genetics and metabolism
Volume113
Issue number1
DOIs
StatePublished - Sep 1 2014
Externally publishedYes

Keywords

  • Asymptomatic carriers
  • Cognitive function
  • Metabolic disease
  • Ornithine transcarbamylase deficiency
  • Urea cycle disorders

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Endocrinology

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  • Cite this

    Sprouse, C., King, J., Helman, G., Pacheco-Colón, I., Shattuck, K., Breeden, A., Seltzer, R., Van Meter, J. W., & Gropman, A. L. (2014). Investigating neurological deficits in carriers and affected patients with ornithine transcarbamylase deficiency. Molecular genetics and metabolism, 113(1), 136-141. https://doi.org/10.1016/j.ymgme.2014.05.007