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