Question

What is the most common mutation found in the CFTR gene? c. Sickle cell anemia is also inherited as an autosomal recessive trait. What gene is mutated to cause sickle cell anemia? (1 pt) d. Why is it advantageous for a person to be heterozygous for the sickle cell trait? (2 pts)

Answer 1

CFTR belongs o ABC transporter family, functions as Cl- channel. Mutation in the CFTR gene leads to the defective synthesis of CFTR protein, cystic fibrosis transmembrane conductance regulator.This defect is due to the deletion of phenylalanine at 508 position of the CFTR gene, producing defective Cl- channel. Due to this, water does not pass into the airways thereby making mucus thick and clogs the airways.

HbS forms a result of a single amino acid substitution in the beta chain of Hb, replacement of glutamate residue at position 6 in the beta chain by a valine residue. Valine,a non polar amino acid, present on the surface of molecule produces hydrophobic spot on the surface, causing aggregation of Hb into tubular fibers and resulting in the distortion of RBC into sickle shape structure.

People with genotype Hb^sHb^s have two copies of mutated gene causing the clogging of blood vessel. People who are heterozygous for Hb^AHb^s have one normal copy and one mutated one because of this malarial parasite is unable to enter and people are resistant to malaria.