Biology 3597A/B Lecture Notes - Lecture 13: Genomic Imprinting, Chromatin, Zygote
25 Jan 2020
School
Department
Course
Professor
Document Summary
Genomic imprinting is established by sex-specific methylation patterns in the developing germ cells. Alleles are methylated in a sex-specific pattern (unknown why this happens: maternal or paternal imprint. Once the zygote forms, certain regions of the genome are imprinted based on methylation of the part of origin of the chromosome. Then methylation is erased in the germ cell lineage of the adult. These are developmental imprinting disorders that are phenotypically different. Caused by the same mutation (identical deletion of chromosome 15) All imprinted regions have an icr (imprint control region) The occurrence of maternal or paternal imprinting depends on the state of the icr: the icr is associated with prader-willi/angelman syndrome, the deletion can occur on either the maternal or paternal chromosome, yield different phenotypes. Maternal deletion = no transcription of ube3a. Paternal deletion = lose expression of the first three genes (ndn, magel2, mkrn3) Prader-willi syndrome and angelman syndrome result from defects in the ch15q11-13 imprinted region.
