Inherited retinal dystrophies in a Kuwaiti tribe.

PURPOSE: To evaluate the clinical and genetic spectrum of inherited retinal diseases (IRDs) in a Kuwaiti tribe. METHODS: Forty four patients with IRDs from 28 nuclear families from the tribe, were evaluated for presenting symptoms, visual acuity, fundus examination, OCT, microperimetry, full-field (ff), and multifocal electroretinography (mERG) and genotyping. RESULTS: Seventeen patients were diagnosed with autosomal recessive retinitis pigmentosa (arRP) associated with RP1 c.606C>A with onset of nictalopia in the third decade, myopia, and macular atrophy by the age of 50; eleven with autosomal recessive cone/rod dystrophy or macular dystrophy associated with RP1 c.606C>A (p.Asp202Glu) mutation with color and central vision deterioration in teenage, myopia, paracentral ring scotoma and macular atrophy; eleven were with arRP associated with PDE6B c.992 + 1 G > A mutation with onset around 5 years, myopia, cataract, retained central fixation, and ellipsoid zone and late perimacular atrophy; five-with Leber congenital amaurosis associated with homozygous RPGRIP1 for c.1107delA mutation with extinguished ffERG and electrophysiological phenotype of rod and cone; and one patient-with autosomal recessive rod-cone dystrophy associated with homozygous PDE6B c.992 + 1 G > A, who was homozygous ABCA4 c.5882 G > A and heterozygous EYS; c.2137 + 1 G > A. CONCLUSIONS: This study represents a typical tribe from the Middle East with high rate of consanguinity for many generations that harbors multiple mutated genes associated with IRD. It demonstrates the predominant phenotype and its variability in retinal disorders caused by identical mutations and illustrates the nuances in the clinical presentation and disease progression of patients with pathogenic mutations in more than one gene.

Registered blindness and low vision in Kuwait.

AIM: To estimate the incidence rates and major causes of registered blindness and low vision in Kuwait. METHODS: Data on age, gender and cause of blindness and low vision were collected from the Visual Disability Committee while evaluating Kuwaiti citizens applying for a blindness allowance from January 2000 to December 2004. Criteria for legal blindness in Kuwait are visual acuity 6/60 or less in the better eye with best possible correction or a visual field less than 20 degrees around the central fixation point. Incidence rates per 100,000 person years of observation were calculated for both genders in four age subgroups and four severity categories. The causes of registered blindness were classified according to the International Classification of Diseases, 10th edition. RESULTS: 412 persons were registered as blind, 272 males (66.01%) and 140 females (33.98%), mean age 28.7 +/-25.2 years, 39.32% below 20 years of age, 31.79% 21-40 years, 18.68% 41-60 years, and 9.95% 61 years and over . Male gender was prevalent for all age subgroups. The overall incidence rate was 9.97 per 100,000 person years of observation, 13.33 for the male and 6.69 for the female patients. The incidence rates rose from 7.35 for those 20 years and younger to 14.80 for the age subgroup 41-60 and 23.16 for those 61 years and above. The rates of severe visual impairment classified in categories 4 and 5 were higher than the rates for categories 2 and 3. Retinitis pigmentosa was the leading cause of blindness, followed by congenital anomalies and optic atrophy. In the subgroup below 20 the rate of optic atrophy was highest, followed by congenital malformations, retinitis pigmentosa and retinopathy of prematurity. In the next age subgroup (21-40 years), the rate of retinitis pigmentosa was three times as high as in the younger subgroup, followed by optic atrophy, congenital malformations and albinism. In the subgroup 41-60 the incidence rate for phthisis bulbi was twice as high as the rates for retinitis pigmentosa and optic atrophy. For those 61 years and older, the incidence rate of phthisis bulbi was almost five times as high as that for optic atrophy. The incidence rates for the male patients were higher for the major causes of disability in all age subgroups. CONCLUSIONS: The overall incidence rate of registered blindness for Kuwait is less than in many other national registries. The marked prevalence of the male gender in all age subgroups is specific for Kuwait. The rates of the leading causes of registered blindness reflect the prevalence of the younger subgroups in our registry. Additional data on co-morbidity and dedicated efforts to reveal unrecognized and unregistered blindness, particularly among females, will overcome the limitations of the registry, and will serve to outline the tendencies in avoidable vision loss and monitor the efficacy of the prevention programs in the future.