Genotyping of TRPV6 alleles. A, TRPV6 locus on human chromosome 7. Genes adjacent to TRPV6 are EPHB (ephrin receptor precursor), TRPV5 and KEL (Kell blood group antigen). Below the structure of the TRPV6 gene with the 15 exons and the coupled polymorphisms 1, 2, 3, 4, and 5. Polymorphisms within introns are not included. The polymorphisms 1, 3 and 5, but not polymorphisms 2 and 4, affect the TRPV6 protein sequence. B, Genotyping of TRPV6 alleles by restriction of amplified DNA using FauI and Bsp1286I to analyze polymorphism 1 (left) and polymorphism 2 (middle) and direct sequencing of amplified DNA to analyze polymorphism 4 and 5 (right). Arrows indicate positions of primer pairs used for DNA amplification.