Rhodopsin Gene Mutation: Prenatal Diagnosis Using Chemical Cleavage of the Mismatch

Abstract

Abstract: : Purpose: Mutations of the rhodopsin gene are responsible for the onset of autosomal dominant or recessive retinitis pigmentosa. Methods: In this study we report the first prenatal diagnosis performed on chorionic villi biopsy of a pregnant woman affected by a severe form of autosomal-dominant transmitted retinitis pigmentosa, due to the Arg135Trp substitution. The rhodopsin gene was analyzed by automated direct sequencing and by Fluorescence-Assisted Mismatch Analysis (FAMA). The latter is an inexpensive, rapid and particularly sensitive method, based on the chemical cleavage of the mismatch in heteroduplex DNA molecules marked with strand-specific fluorophores. Results: FAMA is a feasible procedure to perform prenatal molecular diagnosis of rhodopsin genetic lesions. The redundancy of signals obtained by FAMA and its sensitivity make it suitable for identifying exactly the position of the mutation and the nucleotide substitution. Conclusion: We propose an association between FAMA and automated direct sequencing procedures, in order to achieve optimal results in terms of reliability for prenatal diagnosis of rhodopsin genetic lesions .

Keywords: 420 genetics • 562 retinal degenerations: hereditary • 517 photoreceptors