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Inherited retinal degenerations are a common cause of untreatable blindness worldwide, with retinitis pigmentosa and cone dystrophy affecting approximately 1 in 3500 and 1 in 10,000 individuals, respectively. A major limitation to the development of effective therapies is the lack of availability of animal models that fully replicate the human condition. Particularly for cone disorders, rodent, canine, and feline models with no true macula have substantive limitations. By contrast, the cone-rich macula of a nonhuman primate (NHP) closely mirrors that of the human retina. Consequently, well-defined NHP models of heritable retinal diseases, particularly cone disorders that are predictive of human conditions, are necessary to more efficiently advance new therapies for patients. We have identified 4 related NHPs at the California National Primate Research Center with visual impairment and findings from clinical ophthalmic examination, advanced retinal imaging, and electrophysiology consistent with achromatopsia. Genetic sequencing confirmed a homozygous R565Q missense mutation in the catalytic domain of PDE6C, a cone-specific phototransduction enzyme associated with achromatopsia in humans. Biochemical studies demonstrate that the mutant mRNA is translated into a stable protein that displays normal cellular localization but is unable to hydrolyze cyclic GMP (cGMP). This NHP model of a cone disorder will not only serve as a therapeutic testing ground for achromatopsia gene replacement, but also for optimization of gene editing in the macula and of cone cell replacement in general.

OBJECTIVES To investigate loss of colour vision related to exposure to solvents and the role of three enzyme polymorphisms in modifying the risk in exposed workers. METHODS A sample was studied of 68 male dockyard workers and 42 male community controls with and without neuropsychological symptoms from a previous cross sectional study. Indices of cumulative and intensity based exposure to solvents were calculated for all subjects. Alcohol, drug, and smoking histories were obtained. Colour vision was tested by Lanthony D15d colour vision test. Genotype of glutathione S-transferase M1 and T1 and N-acetyltransferase 2 polymorphisms were determined. RESULTS The relation between impairment of colour vision and exposure to solvents was investigated with multiple regression techniques. Increasing annual exposure to solvents was significantly associated with reduced colour vision (p=0.029). Impairment of colour vision was not associated with neuropsychological symptoms as measured by the Q16 solvent symptom questionnaire. No significant association was found between acquired impairment of colour vision and genetic polymorphisms when GSTM1, GSTT1 or NAT2 phenotypes were included in the analyses. CONCLUSIONS Exposure to mixed solvents is associated with impairment in colour vision, the risk increases with increasing exposure. The risk of impairment of colour vision was not altered in this study by the presence of different GSTM1, GSTT1 or NAT2 polymorphisms.

Gene frequencies for 12 genetic loci have been studied in the district of Almopia in Northern Greece. The frequencies of the G6PD and Hb loci exhibited clinal changes from NW to SE in central Macedonia. In the whole Greek population, the mean proportion of polymorphic loci and the mean heterozygosity were 0.73 and 0.202, respectively. Several stastistically significant differences between Macedonians and Bulgarians were found.

A total of 267 blood samples from persons belonging to the Shrimali Vania Soni caste group in Gujarat State, Western India have been analyzed for 6 blood group, 4 serum protein and 19 red cell enzyme systems, for haemoglobin and β-thalassaemia and for red-green colour blindness. A number of rare genetic variants were detected, including a unique electrophoretically fast variant of Superoxide dismutase. Genetic distance comparisons with other caste groups in Gujarat State show that Vania Soni from Surat are a distinctive group clustering with another subdivision of the Vania. The remaining Vania Soni cluster together and are distinct from the other caste groups examined in Gujarat. However, on the basis of individual genetic markers the Vania Soni appear not to be genetically differentiated in any remarkable way from other Hindu populations in western and northern India.