[Analysis of clinical phenotype and mode of inheritance in retinitis pigmentosa patients with consanguineous marriage].

Objective: To analyse the mode of inheritance and clinical characteristics of retinitis pigmentosa (RP) patients with consanguineous marriage.
Methods: RP patients were recruited for this study in Ningxia Eye Hospital from September 2009 to July 2011. All patients received complete ophthalmic examination. The mode of inheritance were determined based on family history and marriage history. Clinical features were characterized by complete ophthalmic examinations including visual acuity, macular OCT, visual field and electroretinogram (ERG).
Results: A total of 143 individuals with RP (33 families) were recruited. Based on analysis of family history and marriage history, 20 RP families (23 patients) had consanguineous marriage history accounted for 60.6% RP families (16.1% RP patients). There were 4 patients (from 4 families) diagnosed as Usher syndrome. In 20 RP families with consanguineous marriage history, 7 families (35.0%) were Hui ethnicity and 13 families (65%) were Han ethnicity. The marriages of 15 families were between first cousins and 3 families were between second cousins, only 2 families were between half cousins matrimony. Of 23 RP patients, 12 were males and 11 were females. The average age of onset was 11.4 ± 6.8 years and the average age of recruitment was (32.0 ± 13.5) years. The best-corrected visual acuity was less than 0.6 in 78.2% patients. According to the features of the fundus, 13 patients were classical retinitis pigmentosa and 10 patients were retinitis pigmentosa sine pigmento. Visual field examination showed that all patients had varying degrees of peripheral visual field defect. Retinal neuroepithelial layer of macular and peripheral retina became thinner and retinal photoreceptors were disappeared. The average thickness of macular fovea was (186.1 ± 78.7) µm on right eyes and (187.4 ± 76.3) µm on left eyes.
Conclusions: The incidence of RP with consanguineous marriages was high in Ningxia Region. The mode of inheritance of RP patients with consanguinity is autosomal recessive. The common marriage pattern of consanguinity is between first cousins. The age of onset is early and the ocular fundus changes of some patients are atypical, this should be paid attention clinically.