Early-Onset LMNA-Associated Muscular Dystrophy with Later Involvement of Contracture

BACKGROUND AND PURPOSE The early diagnosis of LMNA-associated muscular dystrophy is important for preventing sudden arrest related to cardiac conduction block. However, diagnosing early-onset Emery-Dreifuss muscular dystrophy (EDMD) with later involvement of contracture and limb-girdle muscular dystrophy type 1B is often delayed due to heterogeneous clinical presentations. We aimed to determine the clinical features that contribute to a delayed diagnosis. METHODS We reviewed four patients who were recently diagnosed with LMNA-associated muscular dystrophy by targeted exome sequencing and who were initially diagnosed with nonspecific or other types of muscular dystrophy. RESULTS Certain clinical features such as delayed contracture involvement and calf hypertrophy were found to contribute to a delayed diagnosis. Muscle biopsies were not informative for the diagnosis in these patients. CONCLUSIONS Genetic testing of single or multiple genes is useful for confirming a diagnosis of LMNA-associated muscular dystrophy. Even EDMD patients could experience the later involvement of contracture, so clinicians should consider early genetic testing for patients with undiagnosed muscular dystrophy or laminopathy.