Question

CFTR encodes a chloride ion channel expressed only in the epithelium of the lungs. A person homozygous for a loss-of-function mutation in the CFTR gene will have the genetic disease cystic fibrosis, while a person with one fully functional copy of the CFTR gene will not have the disease. Cystic fibrosis is an example of a;

Phenotype displaying simple Mendelian inheritance

Phenotype caused by recessive allele

Phenotype caused by a mutation in tissue-specific effector gene

Phenotype only seen in homozygotes

All of the above

Answer 1

From the given description above, cystis fibrosis is caused by loss of function mutation in CFTR gene, which encodes a chloride channel. The CFTR is a tissue-specific effector gene. The gene is coded by a recessive allele, making cystic fibrosis is a autosomal recessive disorder. When both of the alleles are recessive, person gets the disease; but when there is only one recessive allele present, the person comes to be normal. In this way, the disease is following Mendelian inheritance as well. This makes all of the statements true.

Hence, the correct option is (e)

About the incorrect options-

All these statements are correct individually, but all of them are correct, which makes them incorrect as an option individually. The only correct option is "all of above".

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