Muscular Impairment In Brazilian Adults With Neurofibromatosis Type 1

Abstract

Neurofibromatosis type 1 (NF1) is a genetic neurocutaneous disorder, autosomal dominant, with multisystemic manifestations, including a predisposition to tumor formation, bone dysplasias, neuromuscular and exercise capacity impairment and motor deficits, such as poor coordination, low muscle tone, and easy fatigability. Recent studies have illustrated a primary role for the NF1 gene product in muscle growth, strength and metabolism. PURPOSE: To evaluate body composition and muscle strength in Brazilian individuals with NF1. METHODS: 26 individuals with NF1 (14 male), aged 18-45 years, were compared to 26 controls, matched by sex, age, body mass index (BMI) and physical activity level. The following anthropometric parameters were measured: weight, height and waist circumference. Body composition was assessed by dual energy X-ray absorptiometry (DXA). The muscular strength was evaluated by the handgrip test using a dynamometer and presented as maximum muscle strength (Fmax) and per unit area (Farea). The physical activity level were evaluated by IPAQ short form. Statistical analyses used: Kolmogorov-Smirnov and T of Student paired. RESULTS: The mean age was 34.31 ± 6.05 and 32.92 ± 6.14 years old in the NF1 and control groups, respectively (p=0.316). Stature was lower in individuals with NF1 (1.61 ± 0.10 vs. 1.68 ± 0.08 meters, p=0.003). There were no differences in weight, BMI, waist circumference, fat mass, fat percentage and body fat index. Appendicular lean mass adjusted by BMI was lower in the NF1 group (0.743 ± 0.190 vs. 0.828 ± 0.161, p=0.048). Individuals with NF1 also presented reduction of Fmax (31.09 ± 12.20 vs. 37.47 ± 10.66 kg, p=0.035) and Farea (13.26 ± 4.17 vs. 15.62 ± 3.58 kg, p=0.028). CONCLUSION: The NF1 group in this study have lower lean mass adjusted for BMI and lower maximal muscle strength. It may indicate an early sarcopenia in this population, which requires further investigation about the mechanisms of these changes and the role of nutrition and exercise on these results. Supported by CAPES and FAPEMIG Grant (APQ-00928-11)