Peripheral muscle weakness in RASopathies.

ABSTRACT

INTRODUCTION: RASopathies are a group of genetic conditions due to alterations of the Ras/MAPK pathway. Neurocutaneous findings are hallmark features of the RASopathies, but musculoskeletal abnormalities are also frequent. The objective was to evaluate handgrip strength in the RASopathies. METHODS: Individuals with RASopathies (e.g., Noonan syndrome, Costello syndrome, cardio-facio-cutaneous [CFC] syndrome, and neurofibromatosis type 1 [NF1]) and healthy controls were evaluated. Two methods of handgrip strength were tested GRIP-D Takei Hand Grip Dynamometer and the Martin vigorimeter. A general linear model was fitted to compare average strength among the groups, controlling for confounders such as age, gender, height, and weight. RESULTS: Takei dynamometer handgrip strength was decreased in each of the syndromes compared with controls. Decreased handgrip strength compared with sibling controls was also seen with the Martin vigorimeter (P < 0.0001). CONCLUSIONS: Handgrip strength is decreased in the RASopathies. The etiology of the reduced muscle force is unknown, but likely multifactorial.