Citation: Sprouse C, King J, Helman G, et al. Investigating neurological deficits in carriers and affected patients with ornithine transcarbamylase deficiency. Mol Genet Metab. 2014;113(1-2):136-141. doi:10.1016/j.ymgme.2014.05.007.
Purpose: To elucidate cognitive deficits in patients with ornithine transcarbamylase (OTC) deficiency (symptomatic: n=25; 18 female, 7 male; “asymptomatic” females: n=20) compared with healthy controls (n=36; 21 female, 15 male) using a battery of tests that assessed multiple domains (academic abilitya, executive functionb, verbal memoryc, nonverbal memoryd, simple attentione, motor dexterityf, and languageg), with all scores normalized to age group (n=81 total participants, aged 7-60 years).
- When compared with healthy controls, symptomatic patients with OTC deficiency demonstrated deficits in executive function, verbal memory, nonverbal memory, motor dexterity, and academic ability.
- Consistent with previous results, “asymptomatic” patients showed deficits in the incongruent portion of the Stroop test, which measures executive function by assessing association of words and colors.1
- Compared with controls, “asymptomatic” patients demonstrated significantly different (P=.04) results in the Purdue Pegboard task, which measures fine motor dexterity by assessing the participant’s ability to place pegs in 2 rows on a pegboard. [
- “Asymptomatic” patients performed similar to controls in language, academic ability, and simple attention, in line with previous reports.2,3
- “Asymptomatic” and symptomatic patients showed no significant differences in measures of simple attention, language, and verbal memory.
- This study demonstrated that while “asymptomatic” patients with OTC deficiency may appear similar to healthy controls in several aspects, cognitive and motor deficits can become apparent when these patients are challenged with tests of executive function and/or fine motor ability.
bAssessments: Stroop test, Comprehensive Trail-Making Test (CTMT), Behavior Rating Inventory for Executive Functioning (BRIEF), digit span backward as part of the Wechsler Intelligence Scale (WIS).
cAssessment: Wechsler Abbreviated Scale of intelligence (WASI)–Verbal Subtest.
dAssessments: Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI), Wechsler Abbreviated Scale of Intelligence (WASI)–Performance Subtest.
eAssessment: Digit span forward subtest of the Wechsler Intelligence Scale (WIS).
fAssessment: Purdue Pegboard.
gAssessments: Peabody Picture Vocabulary Test-Third Edition (PPVT-III), Expressive Vocabulary Test (EVT), Woodcock Johnson III tests of achievement (WJ-III)–Oral Comprehension.