Lecture 29b Human genetic disorders

Lecture 29b Human genetic disorders - Lectur e 29b I nher...

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Unformatted text preview: Lectur e 29b I nher itance patter ns of common human genetic diseases pp265-270 Lear ning Objectives Be able to recognize from a pedigree analysis if a disorder is caused by a recessive or dominant allele. Understand the molecular basis for Cystic fibrosis, sickle cell, and Huntingtons disease Describe techniques used to test carriers or affected individuals MAN Y H UMAN TRAI TS FOLLOW MEN DELI AN PATTERN S OF I N H ERI TAN CE Humans are not convenient subjects for genetic research However, the study of human genetics continues to advance by using a number of different tools that can predict the outcome of human matings. These include both classic and molecular approaches (to be discussed later). Recessively I nherited Disorders Many genetic disorders are inherited in a recessive manner Recessively inherited disorders show up only in individuals homozygous for the allele. For genes that are essential for viability, mutants that are homozygous recessive will die. The time of death will depend on when the product is needed during development or even adulthood. Heterozygous individuals who carry the recessive allele (carriers) are phenotypically normal or almost normal because one copy of the normal gene is sufficient for function. Two carriers have a 1/ 4 chance of having a child with the disorder, 1/ 2 chance of having a child who is a carrier, and 1/ 4 chance of having a child without a defective allele ( know how to figure this out!! This is a cross between an Aa and an Aa individual ). Genetic disorders are not evenly distributed among all groups of humans. A classic approach: Pedigree Analysis A pedigree is a family tree that describes the interrelationships of parents and children across generations....
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Lecture 29b Human genetic disorders - Lectur e 29b I nher...

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