Investigating X-Chromosome Inactivation

Females have two alleles for each gene on the X- chromosome, whereas males have only one. This inequality is balanced by X-chromosome inactivation (XCI). This process transcriptionally silences one X- chromosome in every female cell. The choice of which X-chromosome should be turned-o is considered to be random. Studies on mice have revealed that a locus on the X-chromosome, the X controlling element (Xce), signi cantly in uences the choice of which X- chromosome is inactivated. Renault et al. (2007) studied a family of which many of the females exhibit symptoms of the X-linked recessive disease, Haemophilia A. The XCI ratios of the women in this family were signi cantly di erent from what would be expected if the XCI process was random. This studies result is consistent with the human XCE hypothesis. Random and genetic models of XCI ratios are investigated here in theory and are compared to a sample of XCI ratios. Using goodness-of- fit testing, it is determined which models best fit the data. Anderson-Darling statistics and visual inspection of graphics suggest that a three allele genetic model is a good fit to the data, supporting the human XCE hypothesis.

Autorentext

Sonja Pritchett graduated with highest aggregate from Mount Saint Vincent University in Halifax, NS, in May 2006 with a BSc, major in Mathematics. In May 2009, Sonja graduated with a Masters in Statistics from Dalhousie University, Halifax, NS. She completed this degree on a NSERC scholarship. Sonja now resides in her home town, Labrador City, NL.