For one of your problems on part 1 your problem set, you considered the frequenc
ID: 65235 • Letter: F
Question
For one of your problems on part 1 your problem set, you considered the frequency of carriers of albinism and homozygous normal individuals among European and Tanzanian populations. To refresh your memory, you were told that albinism is an autosomal recessive trait and that the incidence of albinos among Europeans is about 1 in 20,000 people and among Tanzanians in Africa is about 1 in 1,400 (interesting side fact: in general, African communities have higher incidences of albinism). The problem in part 1 of your problem set asked you to compute a couple of genotype frequencies in each population. What you are to do for this problem is to show and explain your work to the following questions: What is the probability of finding a carrier of the albinism gene in the two respective populations (i.e., Europeans and Tanzanians) Now given these probabilities, assuming that a random carrier male from Europe meets a random carrier female from Tanzania on a transatlantic flight, fall in love, get married, and are now expecting a child. What is the overall expected probability that a child born from such a union would be an albino?Explanation / Answer
Albinism is an autosomal recessive trait
Unaffected allele = A
affected allele = a
To be affected with albinism, an individual must have received an affected allele from each parent. The allele frequency at human disease are very low. therefore it is most likely that the parents of an affected individual are unaffected heterozygotes (carriers).
The expected offspring genotypes for the mating between European father and Tanzanian mother albino carriers will be
Aa X Aa, a is affected then 25% AA, 50% Aa and 25% aa offspring
ie 25% aa, is affected and 75% AA and Aa, not affected with albinism.
The overall expected probability that a child born from such a union would be an albino = 25%
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