Practice question

Discriminating single-base changes requires probes that recognize one base difference with high specificity. Allele-specific probes designed complementary to mutant versus wild-type sequence hybridize differentially under high stringency. A single mismatch destabilizes duplex, reducing signal, thus genotype can be inferred. VNTR and SSR detect repeat number variation, not single-base substitution. SNP chip platforms use many such allele-specific probes immobilized for parallel typing. Principle underlying this discrimination involves allele-specific oligonucleotide hybridization, enabling detection of sickle cell GAG to GTG mutation and similar substitutions.