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Genetics and Genomics

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Moderate

Estimation of Recessive Allele Frequency from Affected Births

GENES-BPEUZO

Many recessive genetic abnormalities are lethal, and the affected individuals are not seen among the adult population. Assume the frequencies of the dominant and recessive alleles are represented by ${ p }$ and ${ q }$, respectively.

When there is random mating among parents, the frequencies of the homozygous dominant, heterozygotes, and homozygous recessive individuals are predicted to be ${ p }^{ 2 }$, ${ 2pq }$, and ${ q }^{ 2 }$, respectively.

If a recessive lethal condition seemed occurs one time in every 20,000 births, how might this information be used to estimate the frequency of the recessive allele in the population?

A

The occurrence of the lethal condition is random and therefore no estimate can be made.

B

The frequency of the recessive allele is 1 in 20,000 (0.00005).

C

The frequency of the recessive genotype is 1 in 20,000 (0.00005), so the frequency of the recessive allele is estimated to be 0.0071, from $\sqrt { 0.00005 }$.

D

The frequency of the recessive genotype is 1 in 20,000 (0.00005), so the frequency of the recessive allele is estimated to be 0.0000000025, from ${ { (0.00005 })^{ 2 } }$.