Close proximity of c-erbA2 and c-erbA-beta genes on the short arm of chromosome 3.

The common loss region on the short arm of chromosome 3 (3p) in human breast tumors harbors two members of the c-erbA receptor gene family, c-erbA2 and c-erbA-β, both of which recognize a BamHI polymorphism in human genomic DNA. Analysis of lymphocyte DNAs from 50 normal individuals and lymphocyte and tumor DNAs from 116 breast cancer patients revealed identical genotypes (a/a, b/b or a/b) for both probes. Furthermore, deletion of the same allele (a/- or -/b) of c-erbA2 and c-erbA-β was detected in 25% of the 66 breast tumors from patients with constitutionally heterozygous genotypes for both genes. No sequence homology was detected between the c-erbA2 and c-erbA-β genes, suggesting a physical linkage between these two genes