Question

Microphthalmia is a recessive genetic disorder affecting eye development resulting in eyes that are small and malformed. Microphthalmia can arise from mutations in the SOX2 gene. A family has a history of Microphthalmia due to the inheritance of a recessive mutant allele of SOX2 that has an insertion of 300 base-pairs in the DNA sequence corresponding to the first intron of the SOX2 gene. Indicate whether the following statements are TRUE or FALSE for individuals in the family who are heterozygous for the mutant SOX2 allele described:
Now select the True or False to the following statements:

-These individuals will have two SOX2 proteins produced that differ in length by 300 amino acids.
-These individuals will have two SOX2 alleles that differ in the length of the DNA sequence by 300 base-pairs.
-These individuals will have Microphthalmia.

Answer 1

Answer: 1. These individuals will have two SOX2 proteins produced that differ in length by 300 amino acids. FALSE

2. These individuals will have two SOX2 alleles that differ in the length of the DNA sequence by 300 base-pairs. TRUE

3. These individuals will have Microphthalmia. FALSE

Explanation: 1. It has been said in the question that the mutation is as a result of insertion of extra 300 base pairs which do not mean the same as amino acids. Certain base pairs code for certain amino acids. Most times, three base pairs (coding) code for one amino acid.

2. Individuals who are heterozygous will have the mutant allele longer by 300 base pairs than the wild type allele.

3. In recessive genetic disorder, homozygous recessive genotype produce the disorder. So, individuals who are heterozygous will not have the disorder. Such individuals are only carrier of the disorder.