P.220 Neuropsychological functioning in CMT type 2Z: A case report of language deficits masquerading as intellectual disability

Abstract

CMT type 2Z is an increasingly studied form of CMT caused by mutation in the microrchidia family CW-type zinc finger 2 gene (<i>MORC2</i>). Intellectual disability is commonly reported in the small available literature in individuals with CMT2Z; however, neuropsychological data is lacking in this population, and especially in children. Here we present a case report of an 8-year-old boy with genetically confirmed CMT2Z due to a <i>de novo</i> pathogenic variant in the <i>MORC2</i> gene. This boy was referred for comprehensive neuropsychological evaluation by his neuromuscular multidisciplinary team. Results revealed a pattern of strengths and weaknesses consistent with parent report of developmental, language, and academic difficulties. However, overall thinking skills were highly variable, with Average visual and visuospatial skills in contrast to impaired verbal, working memory, and processing speed skills (WISC-V FSIQ=70, GAI=81; VCI=65, VSI=100, FRI=97, WMI=69, PSI=49). Level of independence day-to-day as rated by his mother fell in the impaired range (Vineland-3 ABC=67). Academic achievement was also impaired across skills (WIAT-III Early Reading Skills SS=40, Single Word Reading SS=52, Alphabet Writing Fluency SS=72, Spelling SS=51, Math Problem Solving SS=51, Numerical Operations SS=68). No clinically significant concerns were endorsed by his mother in terms of social-emotional functioning (i.e., externalizing, internalizing, or behavioral symptoms). Diagnostically, this child presents with a complex picture. Impairments in adaptive functioning raise concern for intellectual disability; however, given this child's uneven intellectual profile, with Average visual/visuospatial skills compared to impaired verbal skills, and impairments in virtually all other receptive and expressive language skills measured on exam, observed qualitatively, and reported by his mother, the most appropriate diagnosis is a language disorder. Children with language disorders have persistent difficulties in use of language due to deficits in production including reduced vocabulary, limited sentence structure, and impairments in discourse. Children with language disorders also have difficulties learning adaptive skills and with academic learning, which is also consistent with this child's profile. More research is needed, but the neurocognitive profile of children with CMT2Z is likely more complex than currently reported.