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Genetic Archaeology
GENETIC ARCHAEOLOGY // PROFILE

POMT1

Protein O-Mannosyltransferase 1

CHR 9
9q34.13

Overview

POMT1 encodes an enzyme essential for the O-mannosylation of alpha-dystroglycan. This post-translational modification process is critical for the function of dystroglycan, a protein that connects muscle cells to the extracellular matrix. Mutations in POMT1 lead to severe congenital muscular dystrophies with ocular and brain anomalies.

📍 Chromosomal Position

9q34.13 (Chromosome 9)

🧬 Gene Category

Hereditary Diseases

🔬 Inheritance

Autosomal recessive

📊 Prevalence

Very rare (<1:100,000)

Function & Significance

POMT1 forms an enzyme complex with POMT2 that transfers O-mannose sugars to serine and threonine residues of alpha-dystroglycan. This glycosylation is essential for the binding of dystroglycan to laminin and other components of the extracellular matrix.

When mutations occur in POMT1, the glycosylation of dystroglycan is disrupted, leading to a weakening of the connection between muscle cells and the extracellular matrix. This results in muscle weakness, degeneration, and the characteristic eye and brain anomalies.

🔬 Dystroglycanopathies

Dystroglycanopathies are a group of muscular dystrophies caused by defective glycosylation of alpha-dystroglycan. Besides POMT1, mutations in POMT2, FKTN, FKRP, and other genes can cause similar phenotypes. The spectrum ranges from mild limb-girdle muscular dystrophies to the severe Walker-Warburg syndrome.

Associated Diseases

  • 🧠 Walker-Warburg Syndrome (WWS)

    Severest form: congenital muscular dystrophy, lissencephaly (smooth brain surface), ocular anomalies, often life-threatening in infancy

  • 💪 Limb-Girdle Muscular Dystrophy Type 2K (LGMD2K)

    Milder form with muscle weakness in the shoulder and pelvic girdle, late onset

  • 👁️ Congenital Eye Anomalies

    Microphthalmia, cataract, retinal dysplasia

🧬 Relevant SNPs

rs121908120
9:132458677
Allele 1

G

/

Allele 2

C

Significance: c.598G>C (p.A200P, Ala200Pro) – Pathogenic variant leading to congenital muscular dystrophy. This mutation impairs enzyme activity and results in reduced dystroglycan glycosylation.

⚕️ Clinical Significance

Diagnosis is made through muscle biopsy (reduced dystroglycan glycosylation), brain imaging (lissencephaly, hydrocephalus), and genetic testing. Early diagnosis is important for genetic counseling and family planning.

Management: Supportive therapy with physical therapy, respiratory support, and nutritional management. No causal therapy is available, but gene therapy approaches are in preclinical development.

Prognose: Walker-Warburg syndrome has a very poor prognosis with life expectancy often under 3 years. Milder forms (LGMD2K) have a better prognosis with normal life expectancy.

📚 Data Sources

The information on this page is based on the following scientific sources:

  • OMIM: #607423 (POMT1), #236670 (Walker-Warburg Syndrome)
  • dbSNP: rs121908120
  • ClinVar: Pathogenic POMT1 variants
  • PubMed: Literature on dystroglycanopathies
  • Orphanet: ORPHA906 (Walker-Warburg syndrome)

Last update: February 2026

Biological Function

POMT1 forms a complex with POMT2 to catalyze protein O-mannosylation. This modification is critical for dystroglycan function in muscle and nerve cells.

Associated Conditions

Walker-Warburg Syndrome (WWS) Muscular Dystrophy-Dystroglycanopathy Limb-Girdle Muscular Dystrophy Type 2K
Molecular Analysis

Analyzed Markers

rs121908120 Pathogenic
Pos: 9:132458677 | Alleles: G/C

c.598G>C (p.A200P) - Pathogenic variant leading to congenital muscular dystrophy.