Introduction to Genetic Analysis 46

Introduction to Genetic Analysis 46 - 45 2.1 Autosomal...

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Unformatted text preview: 45 2.1 Autosomal inheritance heterozygotes, the single functional allele provides enough active protein for the cell’s needs. This situation is called haplosufficiency . Thus the amount of protein is insufficient only if the mutant allele is present in two copies, producing the recessive trait. In pedigree analysis, the main clues for identifying an autosomal dominant disorder with Mendelian inheri- tance are that the phenotype tends to appear in every generation of the pedigree and that affected fathers and mothers transmit the phenotype to both sons and daughters. Again, the equal representation of both sexes among the affected offspring rules out inheri- tance via the sex chromosomes. The phenotype ap- pears in every generation because generally the abnor- mal allele carried by a person must have come from a parent in the preceding generation. (Abnormal alleles can also arise de novo by the process of mutation. This event is relatively rare but must be kept in mind as a possibility.) A typical pedigree for a dominant disorderpossibility....
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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