HSS 3305 Lecture Notes - Lecture 8: Tay–Sachs Disease, Congenital Heart Defect, Polycystic Kidney Disease

• School: University of Ottawa
• Department: Health Sciences
• Course: HSS 3305
• Professor: Benoit Leclerc

Document Summary

Congenital disease: any abnormality present at birth, though it may not be detected until sometime after birth. Hereditary or genetic disease: resulting from a chromosome abnormality or a defective gene. Intrauterine injury to embryo or fetus by drugs, radiation, infection, etc. About 2-3% of all newborn infants have congenital defects. Failure of homologous chromosomes in germ cells to separate (nondisjunction) Monosomy: absence of a chromosome in a cell. Trisomy: presence of an extra chromosome in a cell. Deletions: chromosome breaks during meiosis and broken piece is attached to another non-homologous chromosome with which it is carried along during meiosis. Translocations: misplaced chromosome or part of it attaches to another non-homologous chromosome. Besides germ cells, chromosome nondisjunction also occurs in mitotic zygote during prenatal development. Cells lacking the chromosome (monosomy) cannot survive, while cells with the extra chromosome (trisomy) continues to divide along with the other chromosomally normal cells, called mosaic.