Novel EXT1 mutation identified in a pedigree with hereditary multiple exostoses

Area of Science:

• Genetics
• Molecular Biology
• Orthopedics

Background:

• Hereditary multiple exostoses (HME) is an autosomal dominant skeletal disorder.
• It is characterized by multiple benign cartilage-capped tumors (exostoses).
• Mutations in EXT1 and EXT2 genes, affecting heparan sulfate biosynthesis, are responsible for approximately 90% of HME cases.

Observation:

• A family with typical HME features was studied.
• Sanger sequencing was used for mutation screening.
• A novel heterozygous nonsense mutation (c.1902C>A, p.Tyr634X) in the EXT1 gene was identified in affected individuals.

Findings:

• The identified mutation is located in the glycosyltransferase domain of the EXT1 gene.
• This mutation leads to a premature stop codon, resulting in a truncated EXT1 protein (112 amino acids lost).
• The novel mutation exclusively occurred in all affected family members.

Implications:

• This finding provides crucial evidence for a novel disease-causing mutation in the EXT1 gene.
• It contributes to understanding the genetic basis of HME.
• The discovery supports the development of precise genetic diagnostic tools for HME.