P426 Comparison of motor function measure-20 (MFM20) and neuromuscular gross motor outcome (NM GRO) in young children with LAMA2 or COL6-related dystrophy.

Congenital muscular dystrophies (CMDs) are congenital onset muscular dystrophies with laminin alpha-2 (LAMA2) and collagen VI (COL6)-related dystrophies (RD) being the most common subtypes. Symptoms include hypotonia, progressive muscle weakness, respiratory insufficiency and joint contractures. With multiple promising therapies in development for LAMA2-RD and COL6-RD, the validation of motor outcome measures in young children is essential, given their likely inclusion in future clinical trials. The Motor Function Measure-20 (MFM20) is a 20-item standardized scale used to measure motor function and has been validated in children 2-6 years of age with congenital muscle diseases. The Neuromuscular Gross Motor Outcome (NM GRO) is a 50-item scale, developed by Nationwide Children's Hospital for use in patients from birth onward. The goal of the scale is to assess motor function across the years and reduce the burden of testing. Initial validation studies have been completed in individuals with spinal muscular atrophy (SMA), a motor neuron disease. This exploratory analysis aims to compare MFM20 and NM GRO assessments from the baseline visit of CMD participants younger than 6 years of age. MFM20 and NM GRO were administered to 14 participants: 5 with LAMA2-RD (35.7%) and 9 with COL6-RD (64.3%). Of the 14 participants, 11 were male with the mean age of 3.84 ± 1.11 years. Using Spearman's rank correlation, there was a statistically significant correlation between the MFM20 percentage and NM GRO score (ρ = 0.97, p < 0.001). When individually examining each subgroup, both the COL6-RD group and LAMA2-RD retained statistical significance between the MFM20 percentage and NM GRO score (ρ = 0.94, p < 0.001) and (ρ = 0.87, p = 0.05), respectively. Additional studies, with a larger sample size, are needed to validate the NM GRO as a comprehensive assessment tool for patients with LAMA2-RD and COL6-RD. [ABSTRACT FROM AUTHOR]