Abnormalities in alpha-dystroglycan expression in MDC1C and LGMD2I muscular dystrophies.
We recently identified mutations in the fukutin related protein (FKRP) gene in patients with congenital muscular dystrophy type 1C (MDC1C) and limb girdle muscular dystrophy type 2I (LGMD2I). The sarcolemma of these patients typically displays an immunocytochemical reduction of alpha-dystroglycan. In this report we extend these observations and report a clear correlation between the residual expression of alpha-dystroglycan and the phenotype. Three broad categories were identified. Patients at the severe end of the clinical spectrum (MDC1C) were compound heterozygote between a null allele and a missense mutation or carried two missense mutations and displayed a profound depletion of alpha-dystroglycan. Patients with LGMD with a Duchenne-like severity typically had a moderate reduction in alpha-dystroglycan and were compound heterozygotes between a common C826A (Leu276Ileu) FKRP mutation and either a missense or a nonsense mutation. Individuals with the milder form of LGMD2I were almost invariably homozygous for the Leu276Ile FKRP mutation and showed a variable but subtle alteration in alpha-dystroglycan immunolabeling. Our data therefore suggest a correlation between a reduction in alpha-dystroglycan, the mutation and the clinical phenotype in MDC1C and LGMD2I which supports the hypothesis that dystroglycan plays a central role in the pathogenesis of these disorders.
Brown
Susan C
SC
Dubowitz Neuromuscular Unit, Department of Paediatrics, Faculty of Medicine, Imperial College, Hammersmith Hospital, London, United Kingdom. s.brown@ic.ac.uk
Torelli
Silvia
S
Brockington
Martin
M
Yuva
Yeliz
Y
Jimenez
Cecilia
C
Feng
Lucy
L
Anderson
Louise
L
Ugo
Isabella
I
Kroger
Stephan
S
Bushby
Kate
K
Voit
Thomas
T
Sewry
Caroline
C
Muntoni
Francesco
F
D000328:Adult; D015153:Blotting, Western; D002648:Child; D003598:Cytoskeletal Proteins / Q000096:biosynthesis*; D004252:DNA Mutational Analysis; D049030:Dystroglycans; D005333:Fetus; D006801:Humans; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009136:Muscular Dystrophies / Q000235:genetics* / Q000473:pathology; D009154:Mutation; D010430:Pentosyltransferases; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics
D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D008562:Membrane Glycoproteins; D011506:Proteins; D049030:Dystroglycans; C443107:FKRP protein, human; D010430:Pentosyltransferases