Clinical, molecular pathological and genetic analysis of a Chinese family with dystrophinopathy

Objective To analyze and determine the clinical, molecular pathology and genetic features of a Chinese family with dystrophinopathy. Methods Clinical data of the proband and his family members were collected. Immunohistochemistry staining was performed on muscular biopsy tissues with antimerosin, emerin and the N, C and central rod domains of dystrophin. Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes. Multiplex ligation-dependent probe amplification (MLPA) was used to test Duchenne muscular dystrophy (DMD) gene to determine the ways and sites of genetic mutation, and analyze the relationships between genotype and phenotype. Results Patients from this family were clinically diagnosed as muscular dystrophy, and they presented serious manifestations although the immunohistochemistry analysis for the proband exhibited partial loss of dystrophin staining, and positive expression with merosin and emerin. Further test with MLPA detected the loss of exons 45--54 in DMD gene in the proband, while his mother had heterozygositic loss in exons 45--54. Conclusions The losses of exons 45--54 in the proband are all derived from his mother, who carries genetic mutation with normal phenotype. He has been diagnosed as dystrophinopathy. At the same time, his partial loss of dystrophin is not parallel to the out-of-frame mutation of the gene and his severe clinical manifestations. Abnormal expression of dystrophin is the pathological basis for dystrophinopathy phenotype. Its clinical outcome depends not only on the degree of the protein expression, but also on the function of the sites where the DMD gene less occurs. Key words: Muscular dystrophy, duchenne; Dystrophin; Pedigree; Biopsy; lmmunohistochemistry; Nucleic acid probes