Aa Question 1 [18 marks /18 minutes] In the pedigree to the right, allele a is a

Question

Aa Question 1 [18 marks /18 minutes] In the pedigree to the right, allele a is a rare, auto somal recessive, disease-causing allele. The genotypes of individuals I.1 and L.2 are given. II 2 4 1 IV 1 c) Using the original pedigree, calculate the probability that individual IV.1 wil show the disease if the a allele is dominant. Asume that penetrance of the disease genotype is complete. Explain your answer [6 marks] Based on your answer to part (c), calculate the probability that individual IV.1 will show the disease if the penetrance of the disease genotype is 50%. d) 2 marks

Explanation / Answer

(1)

C.

In autosomal dominant inheritance, only one copy of a disease allele is required for an individual to be affected by the disease. With each pregnancy, there is a one in two (50%) chance the offspring will inherit the disease allele.

The probability of II-2, 3 are being affected is 50% or 1/2

Aa x AA= AA, AA, Aa, Aa (50% individuals will be affected)

Probability of III-1, III-2 being affected is ½ x ½ = ¼

Aa x AA = 50% are Aa

Probability that IV-1 is affected is = ¼ Aa x ¼ Aa= AA, Aa, Aa, aa = 1/16 x ¾ = 3/64

d)

If the penetrance is 50%, With each pregnancy, there is a one in four(%) chance the offspring will inherit the disease allele.

the Probability that IV-1 will show the disease is

1/16 x 1/16 x ½ x ¾ = 3/2048

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.