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Recitation 6 short-answer assignment Cystic fibrosis is an autosomal recessive d

ID: 276662 • Letter: R

Question

Recitation 6 short-answer assignment Cystic fibrosis is an autosomal recessive disorder caused by a loss-of-function mutation in a chlorine channel, which causes a thickening of the mucus, leading to respiratory failure. This disease affects approximately 1 in 1353 newborns in the Republic of Ireland every year. Fill in the following values (1 points each): Current population of Ireland is approximately 4.8 million. Based on the allele frequencies that you calculated, what is the expected number of cystic fibrosis carriers (heterozygotes) in Ireland? Show your work. (1 point) What is the expected number of healthy individuals in the population? Show your work. (1 point) Reminder: only homozygous recessive individuals are affected by the disease.

Explanation / Answer

Hardy-Weinberg equilibrium:
p+q = 1
p2+2pq+q2 = 1

q2 = 1/1353 = 7.39 X 10^-4 = 0.000739
q = 0.02718
p = 1-0.02718 = 0.97281
p2 = 0.94635
2pq = 0.05288

Current population = 4800000
Heterozygotes = 4800000 X 0.05288 = 253824
Affected, q2 = 4800000 + 0.000739 = 3547
Unaffected WT homozygous, p2 = 4800000 + 0.94635 = 4542480
Unaffected individuals p2+2pq = 4542480 + 253824 = 4796304