Example of an autosomal recessive trait mechanism of

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Unformatted text preview: system disorder • Due to mutation of the Hex A gene • Incidence in general U.S. population: 1/320,000 • Incidence in the Ashkenazi Jewish population: 1/3500 Example of an Autosomal Recessive Trait • Tay-Sachs Disease: • Babies become listless and weak at about 6 months • Physiological and neurological condition worsens • Death at 2-3 years. • There is no cure or treatment. Example of an Autosomal Recessive Trait • Mechanism of Tay-Sachs: • Accumulation of a lipid in the brain (GM2 ganglioside). • Affected children are missing the enzyme necessary to break it down (hexosaminidase A). • Accumulates in the brain, causing swelling and other symptoms. • Heterozygotes make half as much enzyme, but it is enough normal. Autosomal Dominant Traits • Do not skip generations (unless incompletely penetrant) • Equal number of affected males and females Autosomal Dominant Traits IF HETEROZYGOUS, OBLIGATE CARRIER • Most affected individuals are heterozygous • ~1/2 the offspring of an affected individual are affected Example of an Auto...
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This document was uploaded on 02/25/2014.

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