Which of the following diseases is transmittable through genes?

Analyze the question: The question asks which disease is passed from parents to children through genes, meaning it is hereditary.

Explain the concept:

• Hereditary (genetic) diseases are caused by faulty genes or chromosomes and are passed from parents to offspring through gametes.
• Infectious diseases are caused by pathogens such as viruses, bacteria and protozoa, and they spread through contact, body fluids, vectors and so on.
• Age-related or degenerative conditions develop as the body changes over time.

Solution, option by option:

• A. HIV/AIDS: This is caused by a virus (Human Immunodeficiency Virus). It spreads through blood, unprotected sex, sharing sharp objects and from mother to child during pregnancy, birth or breastfeeding. This is infection, not transmission through genes, so it is not the answer.
• B. Sickle cell anaemia: This is caused by a mutation in the gene for haemoglobin (HbS instead of HbA). A child gets the disease when they inherit the sickle cell gene from both parents (genotype SS). Parents with genotype AS are carriers. This is a classic example of a disease transmitted through genes, so it is the answer.
• C. Diabetes: Type 1 and Type 2 diabetes both have some genetic predisposition, but diabetes is mainly a metabolic disorder involving insulin, and lifestyle and diet strongly affect it. In WASSCE, the clear-cut inherited disease among these options is sickle cell anaemia.
• D. Presbyopia: This is the loss of the eye lens's ability to focus on near objects as a person ages. It is an age-related condition, not a genetic disease.

Answer: B. Sickle cell anaemia

Tip: For "transmitted through genes" questions, look for classic inherited conditions: sickle cell anaemia, haemophilia, albinism and colour blindness. For infectious diseases, look for a pathogen or vector (e.g. HIV, malaria, cholera).

Also remember the genotype crosses: AS × AS gives 25% AA, 50% AS and 25% SS. This is why genotype compatibility matters before marriage.