X-chromosome inactivation patterns depend on age and tissue but not conception method in humans.

Female somatic X-chromosome inactivation (XCI) balances the X-linked transcriptional dosages between the sexes, randomly silencing the maternal or paternal X chromosome in each cell of 46,XX females. Skewed XCI toward one parental X has been observed in association with ageing and in some female carriers of X-linked diseases. To address the problem of non-random XCI, we quantified the XCI skew in different biological samples of naturally conceived females of different age groups and girls conceived after in vitro fertilization (IVF).

Dosage Compensation in Females with X-Linked Metabolic Disorders.

Through the use of new genomic and metabolomic technologies, our comprehension of the molecular and biochemical etiologies of genetic disorders is rapidly expanding, and so are insights into their varying phenotypes. Dosage compensation (lyonization) is an epigenetic mechanism that balances the expression of genes on heteromorphic sex chromosomes. Many studies in the literature have suggested a profound influence of this phenomenon on the manifestation of X-linked disorders in females.

Female Fabry disease patients and X-chromosome inactivation.

Fabry disease is an X-linked inherited lysosomal storage disorder caused by mutations in the gene encoding α-galactosidase A (GLA). Once it was thought to affect only hemizygous males. Over the last fifteen years, research has shown that most females carrying mutated allele also develop symptoms, demonstrating a wide range of disease severity, from a virtually asymptomatic to more classical profile, with cardiac, renal, and cerebrovascular manifestations.

[Examples of application of X chromosomal markers in familial investigations and personal identification].

Besides autosomal STR loci, markers of sex chromosomes, X and Y, are increasingly more commonly used in genetic analyses aiming at paternity testing or personal identification. The paper presents cases in which analysis of microsatellite loci of the X chromosome (X-STRs) was included in the routine examination and allowed for an unambiguous determination of the relationship between the tested individuals. The cases addressed paternity testing of female children, determination whether the examined women were paternal half-sisters, as well as personal identification of a deceased man.