Direct evidence for suppression of recombination within two pericentric inversions in humans: a new sperm-FISH technique

Article Abstract:

A new technique for estimating frequency of recombination within pericentric inversions has been developed. Crossover in a pericentric inversion brings on reciprocal recombinant chromosomes that are duplicated/deficient for all chromatin distal to breakpoints. Probes have been selected from within the p- and q-arm flanking regions of two human inversions. Two-color fluorescence in situ hybridization (FISH) analysis has been performed on sperm from heterozygous inversion carriers. For chromosome 1 inversion, the recombination frequency of 0.4% was reported. That is below limits of detection for the fusion technique. Simplicity of the FISH technique and ease of scoring make analysis of a sample/population size much larger than previously had been considered possible easier. In all 6,006 sperm have been checked for chromosome 1 inversion and 3,168 have been checked for chromosome 8 inversion.

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Evidence for genetic heterogeneity in X-linked congenital stationary night blindness

Article Abstract:

Evidence exists for genetic heterogeneity for X-linked congenital stationary night blindness (CSNB). Thirty-two families with X-linked CSNB have been studied to identify genetic-recombination events that can help to identify the location of the disease genes. Of those families, 11 had the complete form and 21 had the incomplete form. X-linked CSNB is a nonprogressive retinal disorder characterized by disturbed night vision or the absence of night vision and is clinically heterogeneous.

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Chromosome breakage in the Prader-Willi and Angelman syndromes involves recombination between large, transcribed repeats at proximal and distal breakpoints

Article Abstract:

Chromosome breakage in the Prader-Willi and Angelman syndromes, distinct neurobehavioral disorders, is discussed related to positional cloning from YACs within and near regions of novel DNA sequences potentially associated with the breakpoints. The breakage involves recombination between large, transcribed repeats at distal and proximal breakpoints and it is postulated that END repeats that flank 15q11-p13 mediate homologous recomgintion to bring on the deletion.

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