X chromosome gene expression in human tissues: male and female comparisons.
About 25% of X-linked genes may escape inactivation at least to some degree. However, in vitro results from somatic cell hybrids may not reflect what happens in vivo. Therefore, we analyzed the female/male (F/M) gene fold expression ratio for 299 X-linked and 7795 autosomal genes from 11 different tissues from an existing in vivo microarray database. On average 5.1 and 4.9% of genes showed higher expression in females compared with 7.4 and 7.9% in males, respectively, for X-linked and autosomal genes. A trend was found for F/M gene fold ratios greater than 1.5 for several X-linked genes indicating overexpression in females among multiple tissues. Nine X-linked genes showed overexpression in females in at least 3 of the 11 studied tissues. Of the 9 genes, 6 were located on the short arm and 3 on the long arm of the X chromosome. Six of the 9 genes have previously been reported to escape X inactivation. However, in general, no consistent pattern was seen for the expression of X-linked genes between in vitro and in vivo systems. This study indicates that factors other than the X-inactivation process may impact on the expression of X-linked genes resulting in an overall similar gender expression for both X-linked and autosomal genes.
Talebizadeh
Zohreh
Z
Section of Medical Genetics and Molecular Medicine, Children's Mercy Hospitals and Clinics, University of Missouri at Kansas City School of Medicine, Kansas City, MO 64108, USA.
Simon
Stephen D
SD
Office of Medical Research, Children's Mercy Hospitals and Clinics, University of Missouri at Kansas City School of Medicine, Kansas City, MO 64108, USA.
Butler
Merlin G
MG
Section of Medical Genetics and Molecular Medicine, Children's Mercy Hospitals and Clinics, University of Missouri at Kansas City School of Medicine, Kansas City, MO 64108, USA. Electronic address: mgbutler@cmh.edu.
D000293:Adolescent; D000328:Adult; D002648:Child; D041321:Chromosomes, Human, X; D005260:Female; D020869:Gene Expression Profiling; D050172:Genes, X-Linked; D006801:Humans; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D012727:Sex Characteristics; D014158:Transcription, Genetic