Abstract
Purpose: :
To describe the different types of retinitis pigmentosa (RP) in Northern Tunisia and to determine the genetic forms.
Methods: :
A prospective non-comparative study was conducted. Different forms of RP disease were diagnosed in 99 patients from 56 families living in north Tunisia. 180 individuals had ophthalmic examination including best corrected visual acuity, slit lamp biomicroscopy, fundus photography, in some cases fluorescein angiography or OCT and electroretinogram for patients younger than 18 years. 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. 96.85% of cases were inherited by autosomal recessive transmission. Sporadic cases were estimated to 3.15 %. Patients mean age at initial examination was 36 years (range: 2 to 70 years). Disease onset mean age was 15 years. Earlier onset, before the age of 8 years, with night blindness and difficulty with midperipheral visual field, was noted in 17 patients. 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 common forms, 9 Usher’s syndrome, 4 congenital amaurosis of Leber, 3 progressive cone-rod degeneration, 1 paravenous form and 1 unilateral form. Mutation R91W of RPE65 gene was detected in two families.
Conclusions: :
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 which was estimated to 61 % in 1975 and to 32.5 % in 2004.
Keywords: retinal degenerations: hereditary • clinical (human) or epidemiologic studies: natural history • genetics