MAPPING OF THE GENE ENCODING THE B56-BETA SUBUNIT OF PROTEIN PHOSPHATASE 2A (PPP2R5B) TO A 0.5-MB REGION OF CHROMOSOME 11Q13 AND ITS EXCLUSION AS A CANDIDATE GENE FOR MULTIPLE ENDOCRINE NEOPLASIA TYPE-1 (MEN1)

The multiple endocrine neoplasia type 1 (MEN1) locus has been previous ly localised to 11q13 by combined tumour deletion mapping and recombin ation studies, and a 0.5-Mb region, flanked by PYGM and D11S449, has b een defined. In the course of constructing a contig, we have identifie d the location of the gene encoding the B56 beta subunit of protein ph osphatase 2A (PP2A), which is involved in cell signal transduction pat hways and thus represents a candidate gene for MEN1. We have searched for mutations in the PP2A-B56 beta coding region, together with the 5' and 3' untranslated regions in six MEN1 patients, DNA sequence abnorm alities were not identified and thus the PP2A-B56 beta gene is exclude d as the candidate gene for MEN1. However, our precise localisation of PP2A-B56 beta to this region of 11q13 may help in elucidating the bas is for other disease genes mapping to this gene-rich region.