X-inactivation and human disease: X-linked dominant male-lethal disorders.
X chromosome inactivation (XCI) is the process by which the dosage imbalance of X-linked genes between XX females and XY males is functionally equalized. XCI modulates the phenotype of females carrying mutations in X-linked genes, as observed in X-linked dominant male-lethal disorders such as oral-facial-digital type I (OFDI) and microphthalmia with linear skin-defects syndromes. The remarkable degree of heterogeneity in the XCI pattern among female individuals, as revealed by the recently reported XCI profile of the human X chromosome, could account for the phenotypic variability observed in these diseases. Furthermore, the recent characterization of a murine model for OFDI shows how interspecies differences in the XCI pattern between Homo sapiens and Mus musculus result in discrepancies between the phenotypes observed in patients and mice.
Franco
Brunella
B
Telethon Institute of Genetics and Medicine (TIGEM), Via Pietro Castellino 111, 80131, Naples, Italy.
Ballabio
Andrea
A
D000818:Animals; D004194:Disease; D004622:Embryo, Mammalian / Q000002:abnormalities / Q000196:embryology / Q000378:metabolism; D005804:Genes, Lethal / Q000235:genetics*; D050172:Genes, X-Linked / Q000235:genetics*; D006801:Humans; D008297:Male; D014960:X Chromosome / Q000235:genetics*; D049951:X Chromosome Inactivation / Q000235:genetics*