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Genotype-phenotype correlation in hereditary multiple exostoses.
C Francannet1, A Cohen-Tanugi, M Le Merrer
1Service de Pédiatrie B et de Génétique, Hôtel Dieu, BP 69, Clermont-Ferrand, France.
Journal of Medical Genetics
|July 4, 2001
Summary
Hereditary multiple exostoses (HME) is primarily caused by mutations in EXT1 and EXT2 genes, accounting for over 90% of cases. EXT1 mutations correlate with more severe HME and malignant transformation, aiding clinical management.
Area of Science:
- Genetics
- Molecular Biology
- Clinical Medicine
Background:
- Hereditary multiple exostoses (HME) is an autosomal dominant disorder characterized by bone outgrowths.
- Known genetic loci include EXT1, EXT2, and EXT3, with EXT1 and EXT2 genes encoding key enzymes in heparan sulfate proteoglycan biosynthesis.
Purpose of the Study:
- To investigate the genetic basis of HME in French families.
- To establish genotype-phenotype correlations in HME.
Main Methods:
- Clinical survey of 42 HME families.
- Mutation analysis of EXT1 and EXT2 genes.
Main Results:
- EXT1 and EXT2 mutations accounted for over 90% of HME cases (EXT1: 64%, EXT2: 21%).
- The majority of identified mutations (86%) likely result in loss of protein function.
- Severe HME phenotypes and malignant transformation to chondrosarcomas were associated with EXT1 mutations.
Conclusions:
- This study establishes the first genotype-phenotype correlation for HME.
- Findings facilitate improved clinical management and genetic counseling for HME patients.