Clinical and genetic investigations of three Moroccan families with retinitis pigmentosa phenotypes.

PURPOSE

Progressive inherited retinal dystrophies, characterized by degeneration of rod photoreceptors and then cone photoreceptors, are known as retinitis pigmentosa (RP), for which 89 genes have been identified. Today, only five Moroccan families with RP with a genetic diagnosis have been reported, justifying our investment in providing further clinical and genetic investigations of families with RP in Morocco.

METHODS

The clinical diagnosis based on a combination of a history of night blindness, abnormal rod or rod-cone responses in electroretinography (ERG), and constricted visual field or difficulty perceiving side objects identified three Moroccan families with an RP phenotype. Probands of these families underwent whole exome sequencing (WES), and candidate variants were evaluated for their segregation within family members.

RESULTS

All patients had a history of night blindness and unrecordable rod and cone ERG traces. In addition, one patient had cystoid macular edema, and another had discrete autofluorescence abnormalities, in addition to ellipsoid zone disorganization and narrowed retinal vessels. WES sequencing revealed heterozygous compound mutations in :c.1690G>T//c.1913C>T and in :c.5908C>T//c.6148G>C and a homozygous splice mutation c.1920+2T>C.

CONCLUSIONS

We provide the first description of Moroccan patients with the RP phenotype harboring pathogenic mutations in the and genes and the second description of an individual with RP with a mutation, associated with cystoid macular edema. These data contribute to expand the genetic diagnosis of RP phenotypes in Morocco.