Genetic and physical mapping of 2q35 in the region of the NRAMP and IL8R genes: identification of a polymorphic repeat in exon 2 of NRAMP.

Recent interest has focused on the region of conserved synteny between mouse chromosome 1 and human 2q33-q37, particularly over the region encoding the murine macrophage resistance gene Ity/Lsh/Bcg (candidate Nramp) and members of the Il8r interleukin-8 (IL8) receptor gene cluster. In this paper, identification of a restriction fragment length polymorphism in the IL8RB gene in 35 pedigrees previously typed for markers in the 2q33-q37 interval provided evidence (lod scores > 3) for linkage between IL8RB and the 2q34-q35 markers FN1, TNP1, VIL1, and DES. Physical mapping, using yeast artificial chromosomes isolated with VIL1, confirmed that IL8RA, IL8RB, and the IL8RB pseudogene map within the NRAMP-VIL1 interval, with the physical distance (155 kb) from 5' LSH to 3' VIL1 representing approximately 3-fold that observed in the mouse. Partial sequencing of NRAMP confirmed the presence of the N-terminal proline/serine-rich putative SH3 binding domain in exon 2 of the human gene. Further analysis of Brazilian leprosy and visceral leishmaniasis pedigrees identified a rare second allele varying in a 9-nucleotide repeat motif of the exon 2 sequence but segregating independently of the disease phenotype.