Battle of the X’s: Comparing Gene Expression Between Maternal and Paternal X Chromosomes
Ramona C. Velazquez
Department of Biology
Faculty Supervisor: Scott W. Roy
Genomic imprinting is an epigenetic phenomenon in which the two alleles of certain genes are expressed differently based on parent-of-origin. Genomic imprinting has been extensively studied on autosomes but less so for X-linked genes. To test for differences in expression between the paternally- and maternally-inherited X chromosomes (Xp and Xm, respectively), we used the fact that individuals with Turner Syndrome (X0) and Klinefelter (XXY) differ in the parental origins of their X chromosomes: Xp0 or Xm0 and XpXmY or XmXmY. We compared microarray data between Xm0 and Xp0 Turner patients, and between XmXpY and XmXmY Klinefelter patients. After multiple hypothesis correction, we found no evidence for differences in gene expression of X-linked or autosomal genes. Similarly, we found no evidence for an effect due to the parent-of-origin of the X chromosome across various tissues of a mouse model of Turner syndrome. These results suggest that genomic imprinting of X-linked genes in placental mammals may be limited, though further analyses of tissues more associated with genomic imprinting of autosomal genes are highly desired.