A HIGHLY CONSERVED PROCESSED PTEN PSEUDOGENE IS LOCATED ON CHROMOSOMEBAND 9P21

PTEN/MMAC1/TEP1, encoding a dual-specificity phosphatase, is a tumor s uppressor gene which has recently been cloned and mapped to chromosome 10q23.3. We have shown that germline mutations of PTEN are present in individuals with two hamartoma syndromes: Cowden Syndrome, associated with a predisposition to breast and thyroid cancers, and Bannayan-Zon ana syndrome. Somatic mutations of PTEN have been reported in a variet y of human cancer cell lines, suggesting a potential role for this gen e in the pathogenesis of human malignancies. We report the identificat ion of a highly conserved PTEN processed pseudogene, psi PTEN, which s hares over 98% homology with the coding region of functional PTEN, and its localisation to chromosome 9p21. The high sequence homology of ps i PTEN with the PTEN transcript may potentially lead to misinterpretat ion when performing mutation analyses based on cDNA templates. Caution should be exerted when using such screening approaches.