title: X chromosome inactivation pattern in female carriers of X linked hypophosphataemic rickets.
abstract: X linked hypophosphataemia (XLH) results from an abnormality of renal tubular phosphate reabsorption. The disorder is inherited as an X linked dominant trait and the gene has been mapped to Xp22.1-p22.2. A candidate gene (PEX) has recently been isolated. The most striking clinical features are growth retardation and skeletal abnormalities. As expected for X linked dominant disorders, females are less affected. However, such a gene dosage effect does not exist for renal phosphate reabsorption. Preferential X chromosome inactivation has been proposed as a possible explanation for this lack of gene dosage. We have examined the X inactivation pattern in peripheral blood cells from 12 females belonging to seven families with XLH using PCR analysis at the androgen receptor locus. The X inactivation pattern in these patients did not differ significantly from the pattern in 30 healthy females. The X inactivation pattern in peripheral blood cells does not necessarily reflect the X inactivation pattern in renal cells. However, the finding of a normal distribution of X inactivation in peripheral blood cells indicates that the similarity in the renal handling of phosphate in male and female patients is not related to a ubiquitous preferential X inactivation.
authors.affiliation: Department of Medical Genetics, Ulleval University Hospital, Blindern, Oslo, Norway.
authors.forename: K H
authors.initials: KH
authors.lastname: Orstavik
authors.forename: R E
authors.initials: RE
authors.lastname: Orstavik
authors.forename: J
authors.initials: J
authors.lastname: Halse
authors.forename: J
authors.initials: J
authors.lastname: Knudtzon
mesh_terms: D000328:Adult; D000368:Aged; D004247:DNA / Q000097:blood; D019175:DNA Methylation; D004303:Dosage Compensation, Genetic; D005091:Exons / Q000235:genetics; D005260:Female; D008040:Genetic Linkage; D006579:Heterozygote; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000235:genetics*; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D016133:Polymerase Chain Reaction / Q000379:methods; D011944:Receptors, Androgen / Q000235:genetics; D018911:Trinucleotide Repeats; D014960:X Chromosome
chemical_list: D011944:Receptors, Androgen; D004247:DNA