Looking for classes? Ksquare Career Institute, Bengaluru →
Principles of Inheritance and Variation
X-linked Dominant Inheritance
1 question from 1 paper, each with its answer.
- question
- 1
- paper
- 1
- of Principles of Inheritance and Variation
- 0.51%
Concepts tested
- Father to all daughters pattern
All Questions
2002 AIPMT 1 question
-
A diseased man marries a normal woman. They get three daughters and five sons. All the daughters were diseased and sons were normal. The gene of this disease is : -A father gives his X chromosome to all his daughters and his Y chromosome to all his sons.
If the disease gene is on the X chromosome and is dominant, the affected father ($X^AY$) passes $X^A$ to every daughter, so all daughters are affected, even with a normal mother ($X^aX^a$).
Sons receive the father's Y and the mother's normal X, so all sons are normal.
Cross: $X^AY \times X^aX^a \rightarrow X^AX^a$ (all daughters affected) and $X^aY$ (all sons normal).
This exactly matches the family. An autosomal or X-linked recessive gene would not give this pattern with a normal mother.
So the gene of this disease is sex linked dominant.