01 Genetic Principles

Somatic, Gametes

Mitosis, Meiosis

Terminology

  • multiple alleles but none are dominant

Penetrance, Expressivity

  • AD: not every with gene mutation gets disease

  • variability in severity

Pleiotropy

2 hit

  • 2 hit only applies to tumor suppressor genes

  • 2nd mutation on same chromosome causes cancer

  • mutation in all cells of offspring: 2nd hit = cancer; also can pass to children

Mosaicism

  • mutation during mitosis: new population of cells with different genes

  • can be germline or somatic

  • germline mosaicism: 1 of the gamete cells in parent develops mutation. Offspring will have mutation

  • turner: some cells have 45X. Others have 46xx

McCune-Albrght

  • irregular coast of Maine, like the skin borders

  • child with symptoms must have mosaicism. If germline mutation, child would have died

Heterogeneity

  • multiple mutations can cause disease