Clinical manifestations and prenatal diagnosis of Ullrich congenital muscular dystrophy: A case report

BACKGROUND Ullrich congenital muscular dystrophy(UCMD)is one of the collagen-VI-related myopathies caused by mutations of COL6A1,COL6A2,and COL6A3 genes.Affected individuals are characterized by muscle weakness,proximal joint contracture,distal joint hyperlaxity,and progressive respiratory failure.There is currently no cure for UCMD.Here,we report the clinical manifestations and prenatal diagnosis of compound heterozygous mutations of the COL6A2 gene in a Chinese family with UCMD.CASE SUMMARY A 3-year-old boy,his 4-year-old brother,their parents,and a 20-wk-old fetus in the mother’s womb were included in the study.The brothers had the typical manifestations of the early-severe subtype:A delayed motor milestone(never walking independently),torticollis,scoliosis,proximal joint contracture,distal joint hyperextension,right hip joint dislocation,and calcaneal protuberance.Both brothers were found by whole-exome sequencing and Sanger sequencing to carry two mutations of the COL6A2 gene(c.1353_c.1354insC,p.Arg453Profs-Ter42/c.2105G>A,p.Trp702Ter).The absence of collagen VI staining in the younger brother’s muscle was identified accurately.Genetic counseling and prenatal diagnosis were crucial for the family,as the autosomal recessive genetic disease affected a quarter of the patient’s siblings.The fetus of the mother’s third child underwent prenatal diagnosis and carried the same two mutations of COL6A2,confirmed in the amniotic fluid by multiplex ligation-dependent probe amplification and short tandem repeats.After a painful psychological struggle,the parents finally decided to terminate the pregnancy.CONCLUSION We report a Chinese family suffering from UCMD.By clarifying the COL6A2 mutations in the probands,the parents had the opportunity to opt for voluntary interruption of the third UCMD pregnancy.

Novel collagen VI mutations identified in Chinese patients with Ullrich congenital muscular dystrophy

Background:We determined the clinical and molecular genetic characteristics of 8 Chinese patients with Ullrich congenital muscular dystrophy(UCMD).Methods:Clinical data of probands were collected and muscle biopsies of patients were analyzed.Exons of COL6A1,COL6A2 and COL6A3 were analyzed by direct sequencing.Mutations in COL6A1,COL6A2 and COL6A3 were identifi ed in 8 patients.Results:Among these mutations,5 were novel[three in the triple helical domain(THD)and 2 in the second C-terminal(C2)domain].We also identified five known missense or in-frame deletion mutations in THD and C domains.Immunohistochemical studies on muscle biopsies from patients showed reduced level of collagen VI at the muscle basement membrane and mis-localization of the protein in interstitial and perivascular regions.Conclusions:The novel mutations we identified underscore the importance of THD and C2 domains in the assembly and function of collagen VI,thereby providing useful information for the genetic counseling of UCMD patients.