leptin and Muscular-Dystrophies--Limb-Girdle

To evaluate the potential bone defect in neuromuscular diseases, we conducted a longitudinal study including three groups of patients: 14 Duchenne muscular dystrophies (DMD) and 2 limb-girdle muscular dystrophies (LGMD); 3 Becker muscular dystrophies (BeMD) and 7 spinal muscular atrophies (SMA). Yearly osteodensitometries assessed body composition and bone mineral density (BMD) associated with bone markers and leptin. Along the 7-year study, 107 osteodensitometries showed that bone status evolved to osteopenia in most patients except BeMD. When analyzing the crude values, BMD improved with age in BeMD and SMA but not in DMD/LGMD. The correlation using the Z-scores displayed a decrease in BMD with age in DMD/LGMD for all regions, in SMA at total body less head, whereas BMD increased in BeMD at lumbar spine. As observed in healthy persons, muscular mass and bone tissue were significantly correlated. Glucocorticoids were deleterious on trabecular and cortical bone. Leptin was high in most patients and correlated to fat mass and bone parameters. This study confirms a secondary bone defect in neuromuscular diseases, further confirming the functional relationship between bone and muscle and arguing for regular bone follow-up in patients to prevent fracture risk. Adipose tissue seems to interfere with bone remodeling in neuromuscular diseases.

Topics: Absorptiometry, Photon; Adolescent; Adult; Bone Density; Bone Diseases, Metabolic; Child; Child, Preschool; Female; Humans; Leptin; Longitudinal Studies; Male; Muscular Atrophy, Spinal; Muscular Dystrophies, Limb-Girdle; Muscular Dystrophy, Duchenne; Young Adult

Diseases due to mutations in the lamin A/C gene (LMNA) are highly heterogeneous, including neuromuscular and cardiac dystrophies, lipodystrophies, and premature ageing syndromes. In this study we characterized the neuromuscular and cardiac phenotypes of patients bearing the heterozygous LMNA R482W mutation, which is the most frequent genotype associated with the familial partial lipodystrophy of the Dunnigan type (FPLD). Fourteen patients from two unrelated families, including 10 affected subjects, were studied. The two probands had been referred for lipoatrophy and/or diabetes. Lipodystrophy, exclusively observed in LMNA-mutated patients, was of variable severity and limited to postpubertal subjects. Lipodystrophy and metabolic disturbances were more severe in women, even if an enlarged neck was a constant finding. The severity of hypertriglyceridemia and hirsutism in females was related to that of insulin resistance. Clinical muscular alterations were only present in LMNA-mutated patients. Clinical and histological examination showed an invalidating, progressive limb-girdle muscular dystrophy in a 42-yr-old woman that had been present since childhood, associated with a typical postpubertal FPLD phenotype. Six of eight adults presented the association of calf hypertrophy, perihumeral muscular atrophy, and a rolling gait due to proximal lower limb weakness. Muscular histology was compatible with muscular dystrophy in one of them and/or showed a nonspecific excess of lipid droplets (in three cases). Immunostaining of lamin A/C was normal in the six muscular biopsies. Surprisingly, calpain 3 expression was undetectable in the patient with the severe limb-girdle muscular dystrophy, although the gene did not reveal any molecular alterations. At the cardiac level, cardiac septal hypertrophy and atherosclerosis were frequent in FPLD patients. In addition, a 24-yr-old FPLD patient had a symptomatic second degree atrioventricular block. In conclusion, we showed that most lipodystrophic patients affected by the FPLD-linked LMNA R482W mutation show muscular and cardiac abnormalities. The occurrence and severity of the myopathic and lipoatrophic phenotypes varied and were not related. The muscular phenotype was evocative of limb girdle muscular dystrophy. Cardiac hypertrophy and advanced atherosclerosis were frequent. FPLD patients should receive careful neuromuscular and cardiac examination whatever the underlying LMNA mutation.

Topics: Adolescent; Adult; Arteriosclerosis; Calpain; Cardiomegaly; Child; Diabetes Mellitus, Lipoatrophic; Female; Humans; Lamin Type A; Leptin; Male; Middle Aged; Muscles; Muscular Dystrophies, Limb-Girdle; Mutation; Triglycerides