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Protein O-mannosyltransferase activities in lymphoblasts from patients with alpha-dystroglycanopathies

Hiroshi Manya1, Céline Bouchet, Akiko Yanagisawa

  • 1Glycobiology Research Group, Tokyo Metropolitan Institute of Gerontology, Foundation for Research on Aging and Promotion of Human Welfare, Tokyo, Japan.

Neuromuscular Disorders : NMD
|September 18, 2007
PubMed

Insights

A biochemical assay using lymphoblasts can diagnose congenital muscular dystrophy (CMD) subtypes. This method effectively identifies mutations in POMGNT1, POMT1, and POMT2 genes, aiding in diagnosing alpha-dystroglycanopathies.

Area of Science:

  • Biochemistry
  • Genetics
  • Neurology

Background:

  • Congenital muscular dystrophy (CMD) encompasses alpha-dystroglycanopathies caused by O-mannosylation defects.
  • Six genes are implicated, presenting overlapping clinical phenotypes, complicating diagnosis.

Purpose of the Study:

  • To evaluate a biochemical assay using lymphoblasts for diagnosing alpha-dystroglycanopathies.
  • To assess enzyme activities related to O-mannosylation in CMD patients.

Main Methods:

  • Immortalized lymphoblasts from diagnosed, undiagnosed CMD patients, and controls were utilized.
  • Enzyme activities of protein O-mannose beta1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) and protein O-mannosyltransferase (POMT) were measured.

Main Results:

  • Patients with known POMGNT1 or POMT1 mutations showed significantly reduced POMGnT1 or POMT activity, respectively.
  • Six previously uncharacterized patients with low enzyme activity were found to have pathogenic mutations in POMGNT1, POMT1, or POMT2.

Conclusions:

  • A lymphoblast-based enzymatic assay is a sensitive tool for selecting patients with POMGNT1, POMT1, or POMT2 mutations.
  • This assay aids in assessing the pathogenicity of identified mutations in alpha-dystroglycanopathies.

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