The gene for multiple endocrine neoplasia type 2A (MEN 2A) is closely linked to RBP3 (retinol-binding protein 3, interstitial, probe IRBP.H4) and the DNA marker D10S15 (probe pMCK2), which have been assigned to the proximal long arm of chromosome 10 by linkage analysis both in Caucasian and Japanese populations. We have constructed a rare-cutting restriction map around the RBP3 and D10S15 loci by pulsed-field gel electrophoresis (PFGE). The RBP3 and D10S15 loci appeared to be within a single 160 kb MluI fragment. In 5 patients with MEN 2A, gene rearrangements, such as a gross deletion, were not found in the 880 kb NruI fragment which covered the closest region to the MEN-2A locus from the RBP3 and D10S15 loci.