Genetic Disorders

Haemophilia A is a genetic disorder caused by the deficiency of clotting factor VIII, leading to impaired blood coagulation.

Trisomy refers to the presence of an extra chromosome in a pair. In the case of Edwards syndrome, there is an extra copy of chromosome 18 (i.e., trisomy 18). It is a genetic disorder that leads to severe developmental and physical abnormalities and is often fatal within the first year of life.
- Turner's syndrome is caused by the presence of a single X chromosome (monosomy XO) in females.
- Down syndrome is caused by trisomy of chromosome 21.
- Klinefelter's syndrome results from an additional X chromosome in males (XXY). Hence, trisomy 18 leads to Edwards syndrome, making option (4) the correct answer.

Cooley's Anaemia, also known as Beta-Thalassemia, is a genetic blood disorder that affects hemoglobin production. It is caused by mutations in the HBB gene, which is located on chromosome 11.
This gene encodes the beta-globin subunit of hemoglobin, and mutations lead to reduced or absent beta-globin chains, resulting in abnormal hemoglobin formation and severe anemia.
- Options (1), (2), and (3) are incorrect because they do not carry the HBB gene.
Therefore, Cooley’s Anaemia is controlled by a gene present on chromosome 11.

Let’s analyze each statement: - A. Correct. Haemophilia B is indeed an X-linked recessive disorder.
- B. Incorrect. Haemophilia C is usually inherited in an autosomal recessive manner, not dominant.
- C. Correct. Haemophilia B is caused by a deficiency of clotting factor IX.
- D. Incorrect. Haemophilia A is caused by a deficiency of clotting factor VIII, not factor XII.
Hence, the incorrect statements are B and D.

A) Myasthenia gravis — Auto-immune disorder (IV): This condition causes muscle weakness due to antibodies affecting neuromuscular junctions.
B) Muscular dystrophy — Progressive muscle degeneration (III): It involves progressive weakening and loss of muscle mass.
C) Gout — Urate crystal deposits in joints (I): Caused by elevated uric acid leading to joint inflammation.
D) Osteoporosis — Low bone density, fractures (II): Characterized by fragile bones and increased fracture risk.