A Case of Limb-Girdle Muscular Dystrophy Type R29 Presenting with Myocardial Damage as the Initial Manifestation:A case report

Background Limb-girdle muscular dystrophy autosomal recessive type 29 (LGMDR29) is an exceedingly rare genetic disorder attributed to mutations in the SNUPN gene. The clinical manifestations of this condition are heterogeneous; however, no cases have been documented to date where myocardial damage was the initial presentation in the context of normal motor development. This report aims to describe this novel clinical presentation. Case presentation: A 19-month-old boy developed myocardial injury following an influenza A infection, which was characterized by significantly elevated serum levels of creatine kinase (CK), creatine kinase-MB (CK-MB), and other relevant biomarkers. Cardiac structure and function, as assessed by echocardiography, were found to be normal, and the patient did not exhibit any typical symptoms of muscle weakness. Whole-exome sequencing revealed compound heterozygous variants in the SNUPN gene: NM_005701.4:c.598C > T (p.Gln200*) and NM_005701.4:c.79C > T (p.Arg27Cys), inherited maternally and paternally, respectively. These findings confirmed the diagnosis of LGMDR29. Conclusions To the best of our knowledge, this represents the first documented case of LGMDR29 presenting with isolated myocardial injury as the initial clinical feature. This case expands the known phenotypic spectrum of the disorder and underscores the importance of considering rare muscular dystrophies, such as LGMDR29, in the differential diagnosis of pediatric patients with unexplained myocardial damage, even in the absence of overt musculoskeletal symptoms.