Lecture04-S11b

Lecture04-S11b - BIS 101 7 Apr 11 Human Pedigrees, Mitosis...

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Unformatted text preview: BIS 101 7 Apr 11 Human Pedigrees, Mitosis and Meiosis Autosomal recessive 1. Affected children often from unaffected parents. 2. On average 1/4 of children are affected in mating of 2 heterozygotes. 3. Equal numbers of affected males and females 4. Usually, mating of affected individuals to unrelated unaffected individuals produces normal offspring (this depends on frequency of affected allele in the population). Conversely, consanguineous marriages have a higher chance to produce affected offspring. e.g. Cystic fibrosis (1/25 het in population), PKU X-linked recessive 1. Many more males than females affected 2. None of the offspring of an affected male are affected. 3. None of the sons of an affected male pass on the disease allele. e.g. Red-green color blindness, hemophilia, Duchenne muscular dystrophy X-linked recessive 1. Many more males than females affected 2. None of the offspring of an affected male are affected. 3. None of the sons of an affected male pass on the disease allele. e.g. Red-green color blindness, hemophilia, Duchenne muscular dystrophy Why are there no Y-linked recessive disorders? Autosomal dominant 1. Affected children have at least one affected parent. 2. Usually 1/2 of the children are affected. Most dominant disease traits are rare so most affected individuals are heterozygous. 3. Equal numbers of affected male and females. 4. Except for the very rare case of a new mutation, unaffected parents do not produce affected children (or the disease is not fully penetrant)....
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Lecture04-S11b - BIS 101 7 Apr 11 Human Pedigrees, Mitosis...

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