Final answer:
Thalassemias are inherited blood disorders where there is decreased production of one of the globin chains of hemoglobin, leading to anemia. Beta-thalassemia involves mutations in the beta-globin gene affecting hemoglobin synthesis. The compensatory mechanisms and mutations in these patients illustrate the process of gene family formation.
Step-by-step explanation:
Thalassemias:
Thalassemias are inherited blood disorders characterized by the abnormal production of hemoglobin, which leads to the destruction of red blood cells and anemia. In beta-thalassemia, there is a decreased synthesis rate of the beta-chain of globin, often due to mutations in various locations within the gene encoding this chain.
Genetic data from beta-thalassemia patients provide evidence for the mechanism of gene family formation. For instance, due to the mutations in the beta-globin gene, there is a compensatory overproduction of other globin chains like gamma or delta. This response can lead to the formation of different types of hemoglobin, such as HbA2 or HbF, which usually are not present in high quantities in adults. The existence of multiple loci coding for similar proteins is indicative of gene duplications, which is a key process in the evolution and expansion of gene families.
Another interesting aspect is a mutation in the promoter region of the beta-globin gene can also lead to beta-thalassemia, demonstrating the importance of regulatory elements in gene expression and the development of these disorders.