Molecular analysis of the rhodopsin gene in southern France: identification of the first duplication responsible for retinitis pigmentosa, c.998999ins4.
OBJECTIVE
Mutations in the gene encoding rhodopsin, the visual pigment in rod photoreceptors, were shown to be the most common cause of autosomal retinitis pigmentosa (RP). In order to determine the prevalence of rhodopsin alterations in southern French populations, we examined 52 unrelated patients/families with autosomal dominant RP (adRP=29), RP simplex (6), or unclassified RP (17).


METHODS
The full coding and flanking sequences of the rhodopsin (RHO) gene were scanned using an improved DGGE (denaturing gradient gel electrophoresis) assay, followed by sequencing of abnormal fragments.


RESULTS
This study revealed three RHO mutations in patients with adRP (G106R, R135W, and c.998999ins4) and a number of frequent or rare polymorphisms. No disease-causing sequence variation was found in simplex and unclassified RP pedigrees. Mutation c.998999ins4 has not been previously reported, and appears as the first duplication identified so far in the RHO gene. This frameshift mutation, which is associated with a severe RP, alters the carboxy terminus and predicts a 353-amino acid mutant rhodopsin instead of 348.


CONCLUSIONS
Our study demonstrates that rhodopsin mutations are responsible for only 10.3% of adRP in French populations living in the Mediterranean area in contrast to the 25-35% reported in other populations.
Bareil
C
C
Laboratoire de Génétique Moléculaire, CNRS UPR 1142, Montpellier, France.
Hamel
C
C
Pallarès-Ruiz
N
N
Arnaud
B
B
Demaille
J
J
Claustres
M
M
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D004252:DNA Mutational Analysis; D005260:Female; D005602:France / Q000453:epidemiology; D020440:Gene Duplication; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D012174:Retinitis Pigmentosa / Q000453:epidemiology / Q000235:genetics*; D012243:Rhodopsin / Q000235:genetics*
D012243:Rhodopsin