Cystic fibrosis is inherited as an autosomal recessive condition. A normal couple has one daughter affected with the disease. They are now planning to have another child. What is the chance of her sibling being affected by the disease –
Correct Answer: 4-Jan
Description: Ans. is. 'c' i.e., 1/4 o The fact that one child of a normal couple is affected by an autosomal recessive condition (cystic fibrosis) indicates that both parents are carriers of this condition. o The recurrence risk of autosomal recessive disorders in siblings is 25% (') for each bih. Both the parents are carrier --> 25% children will be affected, 50% will be carrier and 25% will be normal. o From above flow cha it is clear that with each bih :? (i) One chance in four been affected (25%), i.e. the risk of recurrence is 25% for each bih. (ii) Two in four chance to being normal but a carrier (50%) (iii) One in four chance of being normal and unaffected (25%) (iv) Three in four chances of being phenotypically normal (75%), i.e. not manifesting disease
Category:
Pathology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now