Protein O-mannosyltransferase activities in lymphoblasts from patients with alpha-dystroglycanopathies.
Defects in O-mannosylation of alpha-dystroglycan cause some forms of congenital muscular dystrophy (CMD), the so-called alpha-dystroglycanopathies. Six genes are responsible for these diseases with overlapping phenotypes. We investigated the usefulness of a biochemical approach for the diagnosis and investigation of the alpha-dystroglycanopathies using immortalized lymphoblasts prepared from genetically diagnosed and undiagnosed CMD patients and from control subjects. We measured the activities of protein O-mannose beta1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) and protein O-mannosyltransferase (POMT). Lymphoblasts from patients harbouring known mutations in either POMGNT1 or POMT1 showed a marked decrease in POMGnT1 or POMT activity, respectively, compared to controls. Furthermore, we identified pathogenic mutations in POMGNT1, POMT1 or POMT2 in six previously genetically uncharacterised patients who had very low enzyme activity. In conclusion, the lymphoblast-based enzymatic assay is a sensitive and useful method (i) to select patients harbouring POMGNT1, POMT1 or POMT2 mutations; (ii) to assess the pathogenicity of new or already described mutations.
Manya
Hiroshi
H
Glycobiology Research Group, Tokyo Metropolitan Institute of Gerontology, Foundation for Research on Aging and Promotion of Human Welfare, Tokyo, Japan.
Bouchet
Céline
C
Yanagisawa
Akiko
A
Vuillaumier-Barrot
Sandrine
S
Quijano-Roy
Susana
S
Suzuki
Yasushi
Y
Maugenre
Svetlana
S
Richard
Pascale
P
Inazu
Toshiyuki
T
Merlini
Luciano
L
Romero
Norma B
NB
Leturcq
France
F
Bezier
Isabelle
I
Topaloglu
Haluk
H
Estournet
Brigitte
B
Seta
Nathalie
N
Endo
Tamao
T
Guicheney
Pascale
P
D001681:Biological Assay / Q000379:methods; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D015536:Down-Regulation / Q000235:genetics; D049030:Dystroglycans / Q000235:genetics*; D004789:Enzyme Activation / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D005820:Genetic Testing; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008214:Lymphocytes / Q000201:enzymology; D008364:Mannosyltransferases / Q000235:genetics*; D009136:Muscular Dystrophies / Q000175:diagnosis / Q000201:enzymology* / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics*; D011237:Predictive Value of Tests
C483081:DAG1 protein, human; D005819:Genetic Markers; D007527:Isoenzymes; D049030:Dystroglycans; D008364:Mannosyltransferases; D017351:N-Acetylglucosaminyltransferases; C443106:protein O-mannose beta-1,2-N-acetylglucosaminyltransferase; C082696:protein O-mannosyltransferase