This about beta-thalassemia is true

The correct option is All of the above.

To understand why all the given statements are correct, let us break down each option step-by-step:
1. Two genes are necessary to make beta-globin chains:
Beta-globin chains are synthesized under the control of the beta-globin (HBB) gene locus. Humans inherit one beta-globin gene from each parent, meaning a normal individual has exactly two alleles (two genes) responsible for producing beta-globin chains. A defect or mutation in one or both of these genes leads to beta-thalassemia.

2. Mutation of genes decide the severity of the condition:
The severity of beta-thalassemia depends directly on the nature of the genetic mutation. If one gene is mutated (heterozygous state), it usually results in beta-thalassemia minor (a mild, often asymptomatic carrier state). If both genes are mutated (homozygous or compound heterozygous state), the severity depends on whether the mutations cause a partial reduction in beta-globin production (beta⁺ thalassemia) or a complete absence of beta-globin production (beta⁰ thalassemia), leading to moderate (intermedia) or severe (major, Cooley's anemia) clinical conditions.

3. Beta thalassemia is a common condition in West Asia, North Africa and the Mediterranean islands:
Beta-thalassemia is an autosomal recessive blood disorder with a high prevalence in specific geographic regions. It is classically common in populations from the Mediterranean basin (such as Italy and Greece), North Africa, the Middle East (West Asia), Central Asia, India, and Southeast Asia. This geographical distribution is historically linked to malaria endemicity, as carrying the thalassemia trait provides some resistance to malaria.

Since all three statements are medically and genetically accurate, the correct choice is "All of the above".