Citation: Krivitzky L, Babikian T, Lee H-S, Thomas NH, Burk-Paull KL, Batshaw ML. Intellectual, adaptive, and behavioral functioning in children with urea cycle disorders. Pediatr Res. 2009;66(1):96-101. doi:10.1203/PDR.0b013e3181a27a16.
Purpose: To characterize the cognitive, adaptive, and emotional/behavioral functioning of children with urea cycle disorders (UCDs; aged 5 months to 16 years; mean age 7.2 years) using direct testing and parent questionnaires in 92 children with UCDs (33 neonatal onset [NO]; 59 late onset [LO]).
- Among all patients with UCDs, 35% had learning disabilities and 43% were diagnosed with mental retardation/developmental disability.
- In children under 3 years old (n=24), there were significant differences in Bayley-IIIa composite scores, but no apparent differences in ABAS-IIb scores between patients with and without a history of hyperammonemic crisis; there were no significant differences in either measure between the NO and LO patient groups.
- In children aged 3 to 16 years (n=68), there were no significant differences in IQc or ABAS-II scores between patients with and without a history of hyperammonemic crisis; patients with NO had significantly lower scores on both IQ and ABAS-II.
- Among children aged 3 to 16 years, in the NO group (n=16), 50% were in the range of intellectual disability (ID), with 31% severely impaired, while in the LO group (n=52), 25% were in the range of ID, with 4% showing moderate to severe disabilities.
- The percentage of patients showing ID varied by UCD subtype: in patients with argininosuccinate lyase (AL) deficiency, 40% had mild ID and none had severe ID; in patients with argininosuccinate synthetase (AS) deficiency, 50% had ID, including 33% with moderate to severe ID; in patients with ornithine transcarbamylase (OTC) deficiency, 20% had ID, including 6% with severe ID.
- The UCD group as a whole showed difficulty in several key areas including social difficulties, attention problems, and several metacognitive skills (initiation, planning/organization, working memory, and self-monitoring); there were no significant differences between NO and LO patients in the emotional/behavioral and everyday executive skills domains.
- Children with UCDs present with a wide range of cognitive outcomes and even children with LO and presumably less severe disease show evidence of neurocognitive and behavioral difficulties, especially aspects of executive functioning.
bAdaptive Behavior Assessment System-Second Edition, used for all ages.
cIQ was measured by the Wechsler Preschool and Primary Scale of Intelligence (WPPS-III), for ages 3 to 5 years, and the Wechsler Abbreviated Scales of Intelligence (WASI), for ages 6 to 16 years.