Human Genetics & Pedigrees November 29, 2007 BIO 184 Dr. Tom Peavy

TraitDominant FormRecessive Form Hairline Shapewidow’s peak presentwidow’s peak absent Earlobe Formfreeattached Ability to Roll Tonguepresentabsent Frecklingpresentabsent Number of Digitsmore than 5 (polydactyly)five Pigmentationpresentabsent (albinism) Red Blood Cell Shapedisk-shapedsickled (sickle cell anemia) Ability to taste PTCtastes bitterno taste Asparagus responseurine smellsno smell Human Genetic Traits

Huntington Disease: studies of a Venezuelan family (Autosomal Dominant)

Inheritance of Cystic Fibrosis (Autosomal Recessive)

Sex-Linked Recessive Males are more frequently affected than females. Usually, the parents of affected children are normal, but the mother is a carrier. Affected males, when they survive to reproductive age, cannot transmit the phenotype to their offspring unless they mate with a carrier or affected female. Their daughters, however, will all be carriers.

Sex-linked Dominant Behaves like an autosomal dominant except that affected males will transmit the disease to all of their daughters but never to their sons. Males and females can both be affected. However, the disorders are more common in females for two reasons: 1) Females can get the disease from either their mothers or fathers while males can only get the disease from their mothers 2) The allele is often lethal in the hemizygous state, so male embryos die