Abstract: Objective　To explore the clinical characteristics of limb girdle muscular dystrophy (LGMD) 1B and the mutation features of its pathogenic gene LMNA. Method　The clinical data of 2 children with LGMD 1B and their family members were retrospectively analyzed. Screening and validation of possible pathogenic mutation sites were performed by high-throughput sequencing and Sanger sequencing. The pathogenicity of mutation sites was analyzed by literature review, bioinformatics analysis, and muscle tissue biopsy. Results　In one boy aged 3 years and 6 months and one girl aged 4 years, both showed difficulty in walking, fatigue easily and muscle weakness of limbs. Creatine kinase and its isoenzymes were increased. No myogenic damage was found by electromyography. Muscle biopsy showed that the size of muscle fibers varied, and the number of nuclei in muscle fibers increased significantly, which are in accord with the manifestation of muscular dystrophy. The results of high throughput sequencing showed that there were heterozygous mutations in LMNA gene, c.67C>T (p.P23S) and c.1039G>T (p.E347X), in both children respectively, among which C.67C>T had not been reported before. Bioinformatics suggested that this site was pathogenic and conservative among different species. Conclusion　Gene detection is helpful for the diagnosis of LGMD1B.

Key words: 　limb girdle muscular dystrophy 1B;　LMNA gene;　molecular detection