Correct Option
Royal haemophilia, also known as Haemophilia A, is an X-linked recessive genetic disorder. It is characterized by a deficiency in clotting factor VIII, leading to impaired blood coagulation. Since males possess only one X chromosome, they are more susceptible to expressing the disease if they inherit the defective gene from their mother. Females, having two X chromosomes, are typically carriers but usually do not manifest the disease due to the presence of a normal allele on the other X chromosome. The historical association with European royal families, stemming from Queen Victoria being a carrier, gave it the name "royal haemophilia."
Incorrect Options
- Tay-Sachs disease is an autosomal recessive genetic disorder. It is caused by a deficiency of the enzyme hexosaminidase A, leading to the accumulation of gangliosides in nerve cells.
- Cystic fibrosis is an autosomal recessive genetic disorder. It results from a mutation in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene, primarily affecting the lungs and pancreas by causing the production of abnormally thick and sticky mucus.
- Hypertension, or high blood pressure, is a multifactorial disorder. Its development is influenced by a complex interaction of multiple genes and various environmental factors, rather than being a single gene sex-linked condition.