Clinical, pathological, and genetic characteristics of 23 DMD patients in northern China

Duchenne muscular dystrophy (DMD) is a rare X-linked neuromuscular disorder characterised by heterogeneous early manifestations. This study summarised the clinical, pathological, and genetic characteristics of patients with DMD in northern China and identified useful indicators for diagnosis and disease assessment.

Twenty-three DMD patients at the Second Hospital of Hebei Medical University between 2014 and 2022 were retrospectively reviewed. Clinical data, laboratory findings, electrocardiography, electromyography, muscle pathology, dystrophin immunohistochemistry, and DMD gene variants were analysed.

Age at onset ranged from 0.5 to 7.5 years, mainly between 3.5 and 6.0 years. Bilateral lower-limb weakness and exercise intolerance were observed in 21 patients. All patients had elevated myocardial enzymes, decreased serum creatinine, elevated inorganic phosphate, and myogenic changes on electromyography; 22 had elevated transaminases and 17 had abnormal electrocardiograms. Muscle pathology showed connective tissue and fatty infiltration in all cases, with fibre atrophy. Dystrophin immunohistochemistry revealed complete loss of dystrophin-N/C/R in 21 patients and partial loss in two patients. Muscle strength was positively correlated with CK, CKMB, ALT, AST, LDH, and creatinine. Genetic testing identified 15 deletions, five duplications, and three small mutations, including a novel frameshift variant. Among 21 patients with parental testing, 10 mothers were carriers and 11 cases were considered de novo.

DMD exhibited distinct clinicopathological and genetic patterns. Unexplained transaminase or myocardial enzyme elevation, decreased serum creatinine, and early motor abnormalities should prompt DMD genetic testing.