Question

Explain the genetic basis that results in the expression of sickle-cell anaemia disorder.

Answer 1

A single pair of alleles, Hb^A and Hb^S, govern the condition. Only homozygous for Hb^S (Hb^S Hb^S) exhibit the sick phenotype out of the three potential genotypes. Heterozygous people (Hb^AHb^S) seem unaffected, but they are carriers of the disease since there is a 50% chance that the mutant gene will be passed on to their offspring, resulting in sickle cell trait. At position six of the beta-globin chain, valine is substituted for glutamic acid, resulting in the deficiency. Due to this mutation, red blood cells take on the distinctive sickle shape, which causes the hemoglobin molecule to polymerise in low-oxygen environments. While people who inherit one copy of the mutant allele and one normal allele (heterozygous carriers) may show some symptoms of the disorder but are generally less affected, those who inherit two copies of the mutant allele (homozygous for the sickle-cell gene) usually exhibit the severe form of the disease.