OP9 – 2583: Phosphomanomutase deficiency (PMM2-CDG): Assessment of cerebellar dysfunction through ICARS

Abstract

Objective To assess the validity of the International Cooperative Ataxia Rating Scale (ICARS) in children and adolescents with genetically confirmed PMM2-CDG deficiency. Secondary objectives: To compare ICARS results with Nijmegen paediatric CDG rating scale (NPCRS), neuroimaging findings, intelligence quotient (IQ) and molecular data. Methods Observational study including 13 PMM2-CDG patients and 21 control subjects. Ethical permission and informed consents were obtained. Three independent child neurologists rated PMM2-CDG patients with the ICARS, whereas the NPCRS was administered by a single observer. All patients underwent brain MRI and midsaggital vermis relative diameter was obtained. Psychometric evaluations were available in 6 patients. Mann-Whitney U test was used to compare ICARS between patients and controls. To evaluate inter-observer agreement in patients' ICARS, intraclass correlation coefficients (ICC) were calculated. ICARS Internal consistency was evaluated using Cronbach's alpha. Spearman's rank correlation coefficient test was used to correlate ICARS with NPCRS, midsaggital vermis relative diameter, and intelligence quotients (IQ). Results ICARS and ICARS subscores differed between patients and controls (p Conclusion ICARS is a reliable instrument for assessment of PMM2-CDG patients, without significant inter-rater variability. Despite limited sample size, results hint a good correlation between functional cerebellar assessment, IQ and neuroimaging data. ICARS may represent a valuable tool to evaluate therapeutic interventions on cerebellum dysfunction in PMM2-CDG patients.