Diagnosis and etiology of congenital muscular dystrophy

Abstract

Objective: We aimed to determine the frequency of all known forms of congenital muscular dystrophy (CMD) in a large Australasian cohort. Methods:We screened 101 patients with CMD with a combination of immunofluorescence, Western blotting, and DNA sequencing to identify disease-associated abnormalities in glycosylated ␣-dystroglycan, collagen VI, laminin ␣2, ␣7-integrin, and selenoprotein.Results: A total of 45% of the CMD cohort were assigned to an immunofluorescent subgroup based on their abnormal staining pattern. Abnormal staining for glycosylated ␣-dystroglycan was present in 25% of patients, and approximately half of these had reduced glycosylated ␣-dystroglycan by Western blot. Sequencing of the FKRP, fukutin, POMGnT1, and POMT1 genes in all patients with abnormal ␣-dystroglycan immunofluorescence identified mutations in one patient for each of these genes and two patients had mutations in POMT2. Twelve percent of patients had abnormalities in collagen VI immunofluorescence, and we identified disease-causing COL6 mutations in eight of nine patients in whom the genes were sequenced. Laminin ␣2 deficiency accounted for only 8% of CMD. ␣7-Integrin staining was absent in 12 of 45 patients studied, and ITGA7 gene mutations were excluded in all of these patients. LGMD2I ϭ limb-girdle muscular dystrophy type 2I; MDC1C ϭ congenital muscular dystrophy type 1C; MEB ϭ muscle-eyebrain disease; PVDF ϭ polyvinylidene fluoride; SSCP ϭ single strand conformational polymorphism; UCMD ϭ Ullrich congenital muscular dystrophy; WWS ϭ Walker-Warburg syndrome. Conclusions:

Prevalence of congenital muscular dystrophy in Italy

“…This form has often been reported to be the most frequent form of CMD, with values up to 40% of the CMD cases. 11,19 More recent studies 13,14,20 report values similar to those found in our cohort.…”

“…Other recent studies have investigated larger cohorts of CMDs reporting the relative frequencies of CMD subtypes, 13,14 but these mainly reflected the activity of diagnostic centers and were not population studies.…”

Laminin-111 protein therapy prevents muscle disease in the mdx mouse model for Duchenne muscular dystrophy

“…Several lines of evidence suggest positive feedback in the regulation of laminin and ␣ 7 -integrin expression (6,13,15). To test the hypothesis that laminin regulates ␣ 7 -integrin expression, ␣ 7 ␤gal ϩ/Ϫ myoblasts were exposed to 0-200 nM laminin-111 for 24 h. The activity of the ␣ 7 -integrin promoter was measured by ␤-galactosidase cleavage of the nonfluorescent compound fluorescein di-␤-D-galactopyranoside (FDG) to fluorescein.…”

The O-Mannosylation Pathway: Glycosyltransferases and Proteins Implicated in Congenital Muscular Dystrophy

“…The protein substrates for the O-mannosylation pathway have yet to be elucidated, with only a few putative proteins besides ␣-dystroglycan being identified to date. This may be particularly important given that the phenotypes observed in the dystroglycanopathies clearly overlap but also exceed those observed in Duchenne muscular dystrophy (65,78). Thus, like all good science, the cohort of scientists/clinicians in this field have made substantial advances while creating more questions that need to be pursued if we are to better understand the disease-relevant pathway of protein O-mannosylation.…”