BIOL10003 Lecture Notes - Lecture 22: Haemophilia B, Precocious Puberty, X-Inactivation
12 Nov 2018
School
Department
Course
Professor
Document Summary
Xist produces rnai (interference rna) that coats the x chromosome and methylates the chromatin (turns off) Tsix produced by the other chromosome (the on one), stops xist from binding. Haemophilia a: severe impairment of clotting factor viii (7x more common than haemophilia b) factor viii is needed for prothrombin thrombin, thrombin is needed for conversion of fibrinogen. Haemophilia b: mild impairment of clotting due to deficiency of factor ix. Mutation in dystrophin (muscle protein gene) muscle wastes away. Males are infertile, so homozygous females are not possible. Fmr1 gene (fragile x mental retardation protein) Looks like the chromatin is going to break. Expansion is in the promotor region (cgg repeat) Impaired cognitive development, elongated faces, testis, and ears. Normal 6-53 repeats, affected - >200 repeats, pre-mutation 53-200 repeats. Opposite to x-linkage; father to daughter transmission father is zz while mother is zw. Heterochromatised - chromosome becomes very tightly condensed.
