Pedigree analysis why limited number of progeny thus

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Unformatted text preview: aits Pedigrees: Common Symbols (Yes, you need to know these) Pedigrees: Common Symbols (Yes, you need to know these) Example: Pedigree of Waardenburg Syndrome Proband, the person from whom the pedigree is initiated Waardenburg syndrome is an autosomal dominant type of deafness that may be accompanied by fair skin, a white forelock, and visual problems. Pedigree Analysis: Why? • Limited number of progeny; thus Mendelian ratios impossible to discern • Analysis of pedigrees requires recognizing patterns associated with different modes of inheritance Autosomal Recessive Traits UNAFF. PARENTS, CARRY RECESS. WOULD HAVE 3:1 • Normal parents have affected children. • Equal number of males and females affected. • ~1/4 of the offspring of two carriers are affected. Autosomal Recessive Traits • Normal children with affected siblings: 2/3 chance of being a carrier. • Consanguineous matings are sometimes involved. Example of an Autosomal Recessive Trait • Tay-Sachs Disease: • Degenerative nervous...
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