Increased Skeletal Muscle Volume in Women With Familial Partial Lipodystrophy, Dunnigan Variety

Introduction: Familial partial lipodystrophy, Dunnigan variety (FPLD), an autosomal dominant disorder caused by LMNA mutations, is characterized by fat loss from the extremities. However, it is unclear whether these patients appear muscular because of a lack of subcutaneous fat or have an actual increase in muscle mass. Therefore, we compared muscle mass and volume of selected muscles in women with FPLD and control subjects using dual-emission x-ray absorptiometry (DXA) and magnetic resonance imaging (MRI). Methods: Whole-body axial MRI and DXA scans were obtained on 39 women, aged 18 to 65 years, with FPLD and 17 healthy women matched for body mass index and age (group 1). Volumes of muscles in both the thighs, calves, and psoas were calculated from MRI scans and muscle mass in extremities were calculated from DXA. In addition, abdominal MRI and DXA scans were analyzed from 129 healthy, frequency-matched women (group 2). Comparisons between women with FPLD and control subjects were made using ANOVA, adjusting for height, body mass index, and age. Results: Patients with FPLD, compared with control subjects had significantly greater volumes of the thigh muscles, (6358 +/- 1491 vs 5198 +/- 716 mL, P = .002), calf muscles (3133 +/- 713 vs 2397 +/- 335 mL; P < .001), and psoas muscles (210 +/- 51 vs 175 +/- 34 [group 1] and 165 +/- 38 mL [group 2], P < .001). Patients with FPLD also had significantly increased arm and leg muscle masses when measured by DXA (P < .001). Insulin sensitivity, assessed by insulin tolerance tests, was negatively correlated to the calf muscle volume. Conclusions: Female patients with FPLD have increased skeletal muscle volume and mass compared with those of normal women.