Identification of FBN1 gene mutations in patients with ectopia lentis and marfanoid habitus.

BACKGROUND

Marfan syndrome (MFS), inherited as an autosomal dominant trait, typically affects the cardiovascular, skeletal, and ocular systems. Ectopia lentis (EL) is a clinical manifestation of MFS, with stretching or disruption of the lenticular zonular filaments, leading to displacement of the lenses. EL, with or without minor skeletal changes, exists as an independent autosomal dominant phenotype linked to the same FBN1 locus.

METHODS

A consecutive series of 11 patients, affected predominantly by EL, was analysed for FBN1 mutations using PCR, SSCA, and sequencing.

RESULTS

Six mutations were identified, of which three are novel and one is recurrent in two patients, thus establishing a mutation incidence in this group of 7/11 (63%).

CONCLUSIONS

The FBN1 variants reported are clustered in the first 15 exons of the gene, while FBN1 mutations reported in the literature are distributed throughout the entire length of the gene. A different type of FBN1 mutation presents in this group of patients, compared with MFS, with arginine to cysteine substitutions appearing frequently.