¹Center for Molecular Medicine, Division of Endocrinology and Metabolism, University of Connecticut School of Medicine, Farmington, Connecticut, USA

Correspondence: A Arnold, Center for Molecular Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut 06030-3101, USA. E-mail: molecularmedicine@uchc.edu

Received 15 August 2007; Revised 7 November 2007; Accepted 13 December 2007; Published online 20 February 2008.

Abstract

Most patients with refractory secondary/tertiary hyperparathyroidism have monoclonal parathyroid tumors. Inactivating mutations of CDKN1B, encoding the p27 cyclin-dependent kinase inhibitor, were reported to cause hyperparathyroidism in a multiple endocrine neoplasia type 1-like syndrome. Further, there was decreased expression of CDKN1B in parathyroid tumors of patients with chronic kidney disease. We sequenced the entire coding region and splice sites of CDKN1B in 50 parathyroid tumors from 35 patients to see if inactivating mutations could cause monoclonal tumorigenesis in refractory secondary/tertiary hyperparathyroidism. No frameshift, nonsense, or other clearly inactivating mutations were found, nor was there evidence of homozygous deletion or loss of heterozygosity. The absence of clonal inactivating mutations suggests that CDKN1B is not a classical tumor-suppressor gene in secondary/tertiary parathyroid tumors.