From the Guidelines
If a father has Hemophilia A, all of his daughters will inherit the affected X chromosome and become carriers, while none of his sons will inherit the disorder because they receive the Y chromosome from their father. Hemophilia A is an X-linked recessive disorder, which means the genetic distribution follows specific patterns based on the sex of the children and the inheritance of the X chromosome 1. The disorder is caused by mutations in the F8 gene located on the X chromosome, which codes for clotting factor VIII.
When a father has Hemophilia A, he will pass his Y chromosome to his sons, who will not inherit the disorder because they do not receive the affected X chromosome. On the other hand, all of his daughters will inherit his affected X chromosome, making them carriers of Hemophilia A. These carrier daughters typically do not show symptoms because the normal gene on their other X chromosome compensates for the affected gene. However, they have a 50% chance of passing the hemophilia gene to each of their children.
Key points about the genetic distribution of Hemophilia A when the father has the disorder include:
- All daughters will become carriers of Hemophilia A
- None of the sons will inherit Hemophilia A from their father
- Carrier daughters have a 50% chance of passing the hemophilia gene to each of their children
- The disorder is caused by mutations in the F8 gene located on the X chromosome, which codes for clotting factor VIII, as noted in the study by 1.
The genetic distribution and inheritance pattern of Hemophilia A are critical for understanding the risk of transmission to offspring and for providing appropriate genetic counseling to families affected by the disorder 1.
From the Research
Genetic Distribution of Hemophilia A
If the father has Hemophilia A, the genetic distribution of Hemophilia A to his offspring can be explained as follows:
- Hemophilia A is an X-linked recessive disorder, meaning the gene responsible for the condition is located on the X chromosome 2, 3.
- Since the father has Hemophilia A, he must have the mutated gene on his X chromosome.
- When the father passes his X chromosome to his daughters, they will inherit the mutated gene and become carriers of Hemophilia A 4, 5.
- Sons, on the other hand, will not inherit the X chromosome from their father, but rather a Y chromosome, so they will not inherit Hemophilia A from him.
- However, if the mother is a carrier of Hemophilia A, there is a 50% chance that each son will inherit the mutated gene and develop Hemophilia A, and a 50% chance that each daughter will inherit the mutated gene and become a carrier 4, 5.
- In the case of a homozygous female Hemophilia A, where the female has two copies of the mutated gene, all of her sons will inherit the mutated gene and develop Hemophilia A, and all of her daughters will inherit at least one copy of the mutated gene and become carriers 6.