Genetic and phenotypic analyses of retinitis pigmentosa in northern Tunisia

Abstract

Abstract Purpose To describe the different types of retinitis pigmentosa (RP) in Northern Tunisia and to determine the genetic form. Methods A prospective non‐comparative study was conducted. Different forms of RP disease were diagnosed in 99 patients from 56 families living in northern Tunisia. One hundred eighty individuals had ophthalmic examination including best corrected visual acuity, slit lamp biomicroscopy, fundus photography, and in some cases fluorescein angiography, OCT and electroretinogram (ERG). Clinical features, mode of presentation and mode of inheritance were noted. Blood samples were collected for genetic analyses. Gene RPE65 was screened in all affected cases. Results Half of families presented first degree consanguinity. Sixty eight percent of cases were inherited by autosomal recessive transmission. Sporadic cases were estimated to 32%. Patients mean age at initial examination was 36 years (range: 2 to 70 years). Disease onset mean age was 15 years. Severe progression of disease with constriction of visual field, low vision and extended retinal atrophy was seen in 52% of patients. Among the 99 cases of RP, there were 80 commun forms, 9 Usher’s syndrome, 4 congenital amaurosis of Leber, 3 progressive cone‐rod degeneration, 1 paravenous form and 1 unilateral form. Mutation R19W of RPE65 gene was detected in two families. Conclusion RP is a group of clinical and genetic heterogeneous diseases that can lead to blindness. RP in northern Tunisian population presents some particularities. The recessive severe form is largely predominant probably due to the elevated rate of consanguinity in Tunisia.