Question

After isolating DNA from a newly studied human population, it is found that the 112th base of the NGF receptor gene is a “T” in most individuals in this population; in all other human populations in which the gene had been sequenced previously, this base was always found to be an “A.” This newly-discovered polymorphism would be classified as a

single nucleotide polymorphism (SNP)

simple sequence repeat polymorphism (SSR)

insertion/deletion polymorphism (indel)

copy number variation (CNV)

complex variant

Answer 1

Correct answer is single nucleotide polymorphism (SNP)

Since there is only a single nucleotide/base- pair change at 112th base of the NGF receptor gene i, e in some individuals in a population it is T and in other it is A at the same position.

This is not a simple sequence repeat polymorphism (SSR) because in SSR there is different numbers of repeats of 2 or more base pairs in different individuals, but here only a single basepair change occurred.

This is not a case of insertion/deletion polymorphism (indel), because in indel there are either insertion (addition) or deletion of one or more base pairs takes place unlike SNP where a base pair is changes for another.

This is also not a case of copy number variation (CNV) since in CNV a particular section of the gene is present in different copies in different individuals, not a single base pair change.

In complex variant there is larger changes in genome of different individuals which may be even greater then 1 kb. i,e unlike SNP there are larger changes. So the single base pair change in individuals does not defined as complax variant.

So, the correct answer isSingle nucleotide polymorphism (SNP).