This paper demonstrates the utility of the Two-Temperature LATE-PCR endpoint assay by analyzing genomes that are either homozygous or heterozygous for the normal and mutant version of the G269 allele of the human hexosaminidase A (HEXA), a single G-to-A point-mutation responsible for Tay-Sachs disease (TSD). The gene discussed is HEXA; the disease is Tay-Sachs disease.