What causes POMT1-associated congenital muscular dystrophy (MDDGA1)?

Updated: Jul 03, 2019
  • Author: Emad R Noor, MBChB; Chief Editor: Amy Kao, MD  more...
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Answer

POMT1 mutations were first described in the autosomal recessive Walker-Warburg syndrome. The gene codes for the glycotransferase O-mannosyltransferase 1 that along with POMT2 catalyzes the first step of Ser/Thr O-mannosylation.

POMT1 gene mutations have also been described in patients with a muscle-eye-brain phenotype and in patients with limb-girdle muscular dystrophy type 2K who have onset of limb-girdle weakness in the first decade associated with mild-to-moderate mental retardation.

In a large Italian cohort of patients with CMD and reduced α-dystroglycan on muscle immunohistochemistry, cases with normal brain MRI, microcephaly and mental retardation were more frequently associated with mutations in POMT1 and POMT2. [24]

The POMT1 protein is ubiquitously expressed with highest concentrations in testis, skeletal and cardiac muscle, and fetal brain tissue.

Muscle tissue shows severe loss of α-dystroglycan and loss of laminin-α2 binding.


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