Thank you for reporting, we will resolve it shortly
Q.
Which of the following is a quantitative disease caused due to the mutation of chromosome 11?
NTA AbhyasNTA Abhyas 2022
Solution:
Thalassemia: This is also an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carriers for the gene (or heterozygous). The defect could be due to either mutation or deletion, which ultimately results in a reduced rate of synthesis of one of the globin chains (a and b chains) that make up haemoglobin. This causes the formation of abnormal haemoglobin molecules resulting in anaemia, which is a characteristic of the disease. Thalassemia can be classified according to which the chain of the haemoglobin molecule is affected. In alpha-thalassemia, the production of the alpha-globin chain is affected, while in ß-thalassemia, the production of the ß-globin chain is affected.
Alpha-thalassemia is controlled by two closely linked genes HBA1 and HBA2 on chromosome 16 of each parent, and it is observed due to mutation or deletion of one or more of the four genes. The more genes affected, the less alpha-globin molecules are produced.
ß-thalassemia is controlled by a single gene HBB on chromosome 11 of each parent and occurs due to mutation of one or both the genes.
Thalassemia differs from sickle-cell anaemia in that the former is a quantitative problem of synthesizing too few globin molecules, while the latter is a qualitative problem of synthesizing an incorrectly functioning globin.