Question

________ is an example of an X-linked recessive trait.
A. Phenylketonuria
B. Haemophilia
C. Cystic fibrosis
D. Sickle-cell anaemia

Answer 1

Hint:
Before we proceed into the problem, it is important to know the definitions of Haemophilia.
The Greek words haima, which means blood, and philia, which means affection, are the roots of the word haemophilia. Haemophilia is a genetic disorder. This indicates that it is transmitted from the mother to the fetus at conception. An individual with haemophilia has abnormal blood clotting.
Factor VIII (FVIII), a clotting protein, is either absent or deficient in haemophilia A, also known as factor VIII (8) deficiency or typical haemophilia. About one-third of cases, despite being passed down from parents to children, are isolated.

Complete step by step answer:
There is still much to learn about Hemophilia. A genetic bleeding problem called haemophilia prevents the blood from properly clotting. It results from insufficient levels of the clotting factor in the blood.
The inheritance pattern for hemophilias A and B is recessive and X-linked. The X chromosome, one of the two sex chromosomes, is home to the genes associated with various illnesses.
A mutation would need to occur in both copies of the gene in females (who have two X chromosomes) for it to result in the condition.
However, boys have a higher risk of developing the condition since they only have one copy of the X gene.

Option ‘B’ is correct

Note:
Haemophilia cannot be prevented because it is a hereditary disorder, but it can be diagnosed and give the mother information about the dangers of having a child with the condition. The only carriers of this syndrome in the family are females. It is best to visit a doctor if there is a family history of haemophilia and get a blood test to check the clotting factors as well as a molecular genetic test to check for carriers.