In addition to block 2 of msp1 in P. falciparum, other examples of natural sequence variation detectable by using real-time PCR and capillary electrophoresis (variations >5 nucleotides/bp) include duplications and deletions in the 3 ́ noncoding regions (NCRs) of dengue (16) and yellow fever (17) and insertions and deletions in the env gene of HIV (18,19). The gene discussed is ERVW-1; the disease is dengue disease.