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 non-specific 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 undiag-nosed muscular dystrophy or laminopathy.