Particular regions of the X and Y chromosomes share DNA sequence homology to the extent that cross hybridisation occurs. Thus, chromosome painting with a whole Y chromosome probe consistently results in fluorescence on specific regions of the X chromosome as well as the complete Y chromosome. This phenomenon has been exploited to elucidate the structure of unusual X chromosome rearrangements, w...

Ancient or canonical sex chromosome pairs consist of a gene rich X (or Z) chromosome and a male(or female-) limited Y (or W) chromosome that is gene poor. In contrast to highly differentiated sex chromosomes, nascent sex chromosome pairs are homomorphic or very similar in sequence content. Nascent sex chromosomes arise frequently over the course of evolution, as evidenced by differences in sex ...

The importance of X chromosome in the aetiology of premature ovarian failure (POF) is well-known but in many cases POF still remains idiopathic. Chromosome aneuploidy increase is a physiological phenomenon related to aging, but the role of low-level sex chromosome mosaicism in ovarian function is still undiscovered. Standard cytogenetic analysis was carried out in a total of 269 patients affect...

In the fruitfly Drosophila melanogaster, the four male specific lethal (msl) genes are required to achieve dosage compensation of the male X chromosome. The MSL proteins are thought to interact with cis-acting sites that confer dosage compensation to nearby genes, as they are detected at hundreds of discrete sites along the length of the polytene X chromosome in males but not in females. The hi...

We thank Dr Ozcelik for his careful reading of our review and his thoughtful letter. Dr Ozcelik raises the issue of nonequivalence of monosomy X frequency and X-chromosome inactivation pattern (XCIP). The first refers to the proportion of cells with a single X chromosome, wherein transcription occurs from the lone X chromosome. The second refers to the ratio of inactivated maternal to paternal ...

X chromosome dosage compensation is required for male viability in Drosophila. Dosage compensation relative to autosomes is two-fold, but this is likely to be due to a combination of homeostatic gene-by-gene regulation and chromosome-wide regulation. We have baseline values for gene-by-gene dosage compensation on autosomes, but not for the X chromosome. Given the evolutionary history of sex chr...

We thank Dr Ozcelik for his careful reading of our review and his thoughtful letter. Dr Ozcelik raises the issue of nonequivalence of monosomy X frequency and X-chromosome inactivation pattern (XCIP). The first refers to the proportion of cells with a single X chromosome, wherein transcription occurs from the lone X chromosome. The second refers to the ratio of inactivated maternal to paternal ...

total or partial absence or excess of the sex chromosomes produces different karyotypes and phenotypical abnormalities. upon retrospective analysis of the results of 163444 cytogenetic tests that were performed during 28 years (1987-2015) in this center, different types of sex chromosomal aberrations and the clinical phenotypes are delineated in this article. moreover, the clinical course and t...

We thank Dr Ozcelik for his careful reading of our review and his thoughtful letter. Dr Ozcelik raises the issue of nonequivalence of monosomy X frequency and X-chromosome inactivation pattern (XCIP). The first refers to the proportion of cells with a single X chromosome, wherein transcription occurs from the lone X chromosome. The second refers to the ratio of inactivated maternal to paternal ...

Recessive mutations in three autosomal genes, him-1, him-5 and him-8, cause high levels of X chromosome nondisjunction in hermaphrodites of Caenorhabditis elegans, with no comparable effect on autosomal disjunction. Each of the mutants has reduced levels of X chromosome recombination, correlating with the increase in nondisjunction. However, normal or elevated levels of recombination occur at t...