Question

6. 11-5 and 1-6 meet while attending a lecture concerning a rare metabolic disease. They each have at least one sibling who has the disease. What is the probable mode of inheritance for this disease? 1l-5 and I-6 fall in love but are apprehensive about having children since they know that the chance of their first child having the disease is increased. What is the probability that one of their children will inherit the disorder? English (United States) age 3 of 4 289 words MacBook Pro

Answer 1

Since, when we see siblings of II 5; male and female both are affected, so the disease could not be sex linked. Further, since all progeny (or maximum) are not affected ruling out possibility of autosomal dominant. So, mode of inheritance of given rare metabolic disease is probably AUTOSOMAL RECESSIVE. Since, both have atleast one sibling affected therefore both parents must have an allele and should be carrier for the disease; as an affected individual must inherit a recessive allele from both parents.

If A is dominant over a, then Genotype of parents : Aa

Therefore, unaffected offspring can be carrier Aa; or normal AA while affected one are aa.

Probability of II5 and II6 child to be affected depends upon:

Case 1: if both are AA then probability is nil.

Case 2: if one is AA and other Aa then probability is 25%.

Case 3: if both are carriers, Aa then probability is 25%.

Since chances of case 3 are more as 50% II have chance of being carrier so, probability of their child being affected is 25%, with 50% chance of being the carrier and 25% to be unaffected and neither a carrier.

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