Question

Which one of the following Mendelian disorders is influenced by diet?

• A. Cystic fibrosis
• B. Haemophilia
• C. Phenylketonuria
• D. Thalassemia

Hint:

For PKU, strict dietary control is essential to prevent harmful neurological effects due to phenylalanine buildup.

Answer 1

The Correct Option is C

Phenylketonuria (PKU) is a genetic disorder caused by mutations in the gene encoding the enzyme phenylalanine hydroxylase. This enzyme normally converts phenylalanine, an amino acid found in many foods, into another amino acid called tyrosine. In individuals with PKU, this enzyme is deficient or absent, leading to the accumulation of phenylalanine in the blood and tissues.
[6pt] If PKU is left untreated, the elevated phenylalanine levels can cause severe intellectual disabilities, brain damage, seizures, and other neurological symptoms. However, the condition can be managed with a strict diet that limits phenylalanine intake. This dietary restriction typically includes avoiding high-protein foods such as meat, dairy, and eggs, which contain high levels of phenylalanine. Patients with PKU are also given a special low-phenylalanine medical formula to ensure they receive adequate nutrition. This demonstrates that diet plays a crucial role in the management of PKU.
[6pt] Other disorders listed do not have a similar direct dietary influence:
[6pt] - Cystic fibrosis: This is a genetic disorder that affects the lungs, pancreas, liver, and intestines. It causes the production of thick, sticky mucus, leading to respiratory and digestive issues. While diet can support treatment (e.g., enzyme supplements and a high-calorie diet), it is not directly influenced by diet in the same way PKU is.
[6pt] - Haemophilia: Haemophilia is a genetic disorder where blood does not clot properly due to a deficiency of clotting factors. Although proper nutrition can aid in overall health, haemophilia is not directly influenced by diet.
[6pt] - Thalassemia: Thalassemia is a blood disorder characterized by the abnormal production of hemoglobin. It can be managed through blood transfusions and iron chelation therapy, but it is not influenced by diet in the same way PKU is.