Genetic admixture studies on four in situ evolved, two migrant and twenty-one ethnic populations of Tamil Nadu, south India.

We analysed the genetic structure of ≈ 1000 samples representing 27 ethnic groups settled in Tamil Nadu, south India, derived from two linguistic families (Dravidians and Indo-Europeans) representing four religious groups (Hinduism, Islam, Christianity and Jainism) using 11 mtDNA markers. Out of 27 ethnic groups, four are in situ populations (Anglo-Indian, Labbai Muslim, Nadar Christian and south Indian Jain) and two are migrants (Gypsy and north Indian Jain) from north India to Tamil Nadu, and 21 are native ethnic groups. Six of the markers we used were monomorphic (HaeIII663, HpaI3592, AluI5176, AluI7025, AluI13262, 9-bp deletion) and five markers were polymorphic (DdeI10394, AluI10397, HinfI12308, HincII13259 and HaeIII16517).

Autosomal recessive retinitis pigmentosa locus RP28 maps between D2S1337 and D2S286 on chromosome 2p11-p15 in an Indian family.

Retinitis pigmentosa (RP) is a group of clinically and genetically heterogeneous disorders characterised by night blindness, constriction of visual field, and dystrophic changes of the retina. Previous genetic studies have shown extensive allelic and non-allelic genetic heterogeneity of RP. Here we describe an Indian family with multiple consanguineous marriages and a total of four patients with autosomal recessive (AR) RP.

[Annual school and menarche rhythms (vacation-study)].

Background: It has been hypothesized that the yearly menarche rhythm could be caused by the seasonal variation of photoperiod and temperature or by the annual distribution of the scholar vacation and study periods.

Aim: To test the hypothesis that the distribution of study vacation periods is a condition that modifies the annual menarche rhythm.

Subjects And Methods: Two thousand ninety four school girls from Chile, 2,356 girls from Madras, India, 3,454 girls from Medellin, Colombia and 2,627 girls from Debrecen, Hungary, were studied.

Mutations in RPE65 cause autosomal recessive childhood-onset severe retinal dystrophy.

Autosomal recessive childhood-onset severe retinal dystrophy (arCSRD) designates a heterogeneous group of disorders affecting rod and cone photoreceptors simultaneously. The most severe cases are termed Leber congenital amaurosis (LCA), while the less aggressive forms are usually considered juvenile retinitis pigmentosa. Recently, mutations in the retinal-specific guanylate cyclase gene were found in patients with LCA.