THE GENE FOR MANNOSE-BINDING PROTEIN MAPS TO CHROMOSOME-10 AND IS A MARKER FOR MULTIPLE ENDOCRINE NEOPLASIA TYPE-2

Human mannose-binding lectin (MBL) is a serum protein which appears to function as an opsonin in first line host defense. In situ hybridization studies assign the human MBL gene to chromosome 10q11.2 --> q21. A restriction fragment length polymorphism (RFLP) was found using TaqI with a 0.8-kb cDNA probe for MBL (probe 48-11), yielding heterozysity in 34% of individuals tested. Using this biallelic RFLP, linkage analysis of 30 families confirms the assignment of MBL to the region of multiple endocrine neoplasia, type 2a (MEN2A) with a maximum lod score of 7.54 at a recombination fraction of 0.00 (males) and 0.097 females). The presence of two crossovers between MEN2A and MBL in these families indicates that a defect of MBL itself is not the cause of the hereditary thyroid cancer syndrome. The addition of MBL to the genetic map of the pericentromeric region of chromosome 10 should prove useful for improved localization of the MEN2A mutation.