Natural history of skeletal muscle laminopathies: a 2-year prospective study

Skeletal muscle laminopathies (SMLs) are rare disorders characterized by skeletal muscle involvement caused by mutations in LMNA gene. To date, the natural history of SMLs has not been clearly elucidated. Through a 2-year prospective study, we aimed to describe the natural history of SMLs. We enrolled 26 SMLs patients, assessed with: North Star Ambulatory Assessment scale (NSAA), timed tests, manual muscle testing, joint range of motion, six-minutes walking test (6MWT); respiratory evaluation including forced vital capacity (FVC) and forced expiratory volume at 1 second (FEV1); individualized neuromuscular quality of life (INQoL). Muscular performance with the aforementioned tools significantly correlated with phenotypes at the baseline, showing the worse outcome in those with autosomal dominant Emery-Dreifuss muscular dystrophy as compared to limb girdle phenotype. NSAA score significantly (p = 0.0005) worsened during the 2-year follow-up. Moreover, the respiratory function through FVC and FEV1 significantly (p = 0.0086 and p = 0.0290, respectively) deteriorated over the follow-up period. 6MWT, INQoL and timed tests did not significantly change, as well as ankle, knee, and elbow contractures. This study showed a slow progression of motor and respiratory function in SMLs patients over a period of 2 years.