Practice question

Detecting single-base sickle cell mutation GAG to GTG requires discrimination of one nucleotide difference. Approach uses two allele-specific oligonucleotide probes, one perfectly complementary to normal allele containing GAG codon and another complementary to mutant allele containing GTG. Under stringent hybridization, only fully matched probe-target duplex remains stable and yields signal. Heterozygotes show both signals, homozygotes one signal. Restriction enzyme or generic STR analysis cannot achieve single-base specificity. Paired complementary probes enable precise molecular diagnosis of point mutations via hybridization patterns.