No evidence for a genetic blueprint: The case of the “complex” mammalian photoreceptor.

Despite the intensity of the search for genes causing inherited retinal degenerations over the past 3 decades, of the approximately 200 disease genes identified to date, all appear to be ordinary housekeeping genes specifying proteins playing basic structural and functional roles in the mature photoreceptor cells. No genes or genetic elements have been identified which can be construed as having a specific morphogenic role, directing the development of the cytoarchitecture of any particular retinal cell. The evidence suggests that the cytoarchitecture of the retinal photoreceptors, although enormously complex, arises from the self‑organization of the cells constituents without any regulation or direction from an external genetic blueprint.

Retinitis pigmentosa patients with sickle cell disease and dextrocardia and situs inversus syndrome.

Two cases of retinitis pigmentosa (RP) with associated sickle cell disease in one patient, and situs inversus totalis in the other are reported. To our best knowledge, these associations have never been reported in RP.

Genetic profile of 81 retinoblastoma patients from a referral hospital in southern India.

PURPOSE: To determine chromosomal abnormalities and inheritance pattern in patients with retinoblastoma from a referral hospital in southern India. MATERIALS AND METHODS: Eighty-one retinoblastoma patients from 78 families were included in this study. Peripheral venous blood was taken for chromosomal analysis and pedigree was ascertained for segregation analysis. RESULTS: Male to female ratio was 1.7:1, 55.56% were bilateral retinoblastoma, the mean age of onset was 12.37 months in bilateral and 33.07 months in unilateral cases (p=0.048). Majority (90.12%) had sporadic inheritance and 6.17% had autosomal dominant inheritance. In chromosomal abnormalities, 8.33% had 13q14 deletion, three cases had de novo balanced translocations. CONCLUSION: The age of onset of the disease was much earlier in the bilateral cases compared to unilateral cases. Sporadic inheritance was predominant while only a small percentage of patients had autosomal dominant inheritance. The percentage of patients with 13q14 deletion was higher than reported in the literature and three novel chromosomal translocations were observed. This is one of the largest series of cases reported from India.