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genetic - guriyah
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07-19-2006, 06:13 AM
Tay-Sachs disease occurs almost exclusively among Ashkenazi Jews, with an incidence of 1/3600. The frequency of carriers of the Tay-Sachs gene is which of the following ?
A 1/4 B 1/30 C 1/60 D 1/600
07-19-2006, 06:20 AM
B..
The frequency can be calculated from the Hardy-Weinberg law, in which the carrier frequency is equal 2 pq. q is calculated by taking the square root of the incidence, which gives the frequency of the gene, 1 in 60, and p equal to 1-q, or 60/60-1/60, which gives 59/60. As can be seen here, in most cases of rare diseases, p becomes equal to 1, and the carrier frequency becomes 2q, or 2 times 1/60, which gives the frequency of 1/30. |
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