Succinate Dehydrogenase D Variants Do Not Constitute a Risk Factor for Developing C Cell Hyperplasia or Sporadic Medullary Thyroid Carcinoma

0021-972X/05/$15.00/0 Printed in U.S.A. The Journal of Clinical Endocrinology & Metabolism 90(4):2127–2130 Copyright © 2005 by The Endocrine Society doi: 10.1210/jc.2004-2059 BRIEF REPORT Succinate Dehydrogenase D Variants Do Not Constitute a Risk Factor for Developing C Cell Hyperplasia or Sporadic Medullary Thyroid Carcinoma Alberto Cascon, Arancha Cebrian, Marina Pollan, Sergio Ruiz-Llorente, Cristina Montero-Conde, Rocio Leton, Ruth Gutierrez, Fabienne Lesueur, Roger L. Milne, Olga Gonzalez-Albarran, Tomas Lucas-Morante, Javier Benitez, Bruce A. J. Ponder, and Mercedes Robledo Hereditary Endocrine Cancer Group (A.Ca., S.R.-L., C.M.-C., R.L., R.G., M.R.), Centro Nacional de Investigaciones Oncológicas, Madrid, Spain; Cancer Research United Kingdom (A.Ce., F.L., B.A.J.P.), Department of Oncology, University of Cambridge, Cambridge, United Kingdom; Cancer Epidemiology Service (M.P.), National Center for Epidemiology, Carlos III Institute of Health, Madrid, Spain; Department of Human Genetics (R.L.M., J.B.), Centro Nacional de Investigaciones Oncológicas, Madrid, Spain; Endocrinology Service (O.G.-A.), Hospital Ramon y Cajal, E-28029 Madrid, Spain; and Endocrinology Service (T.L.-M.), Clinica Universitaria Puerta de Hierro, Madrid, Spain Medullary thyroid carcinoma (MTC) is a tumor that arises from parafollicular cells of the thyroid gland. MTC can occur sporadically (75%) or as part of inherited cancer syndromes (25%). In most cases, hereditary MTC evolves from preneoplastic C cell hyperplasia (CCH), so early detection of this pathology would evidently be critical. A recent study reports that alterations in succinate dehydrogenase (SDH) D are responsible for familial non-RET CCH. First, we studied SDHD in two families with hereditary non-RET CCH and found no alterations related to the inheritance of this disease. Then, we investigated whether the H50R variant could be a risk factor M EDULLARY THYROID CARCINOMA (MTC) is a calcitonin-secreting tumor originating in the parafollicular cells (C cells) of the thyroid gland, and it represents about 5–10% of all thyroid malignancies. MTC occurs in both hereditary (25%) and sporadic (75%) clinical settings (1). In familial cases, it only occurs in familial MTC or as a component of multiple endocrine neoplasia type 2A or multiple endocrine neoplasia type 2B (2). Although C cell hyperplasia (CCH) is a relatively common abnormality in middle-aged adults, CCH usually precedes as precursor lesion the development of MTC (3, 4). In fact, most patients with hereditary MTC first develop CCH (5); hence, early detection of this pathology is vital in the clinical outcome of these patients. A recent study (6) described a family with CCH as being attributable to a change in succinate dehydrogenase (SDH) D. This gene codes for one of the mitochondrial SDH subFirst Published Online December 28, 2004 Abbreviations: BC, Basal calcitonin; CCH, C cell hyperplasia; CI, confidence interval; dHPLC, denaturing HPLC; F1, family 1; F2, family 2; MTC, medullary thyroid carcinoma; OR, odds ratio(s); PCC, pheochromocytoma; PG, pentagastrin-provoked calcitonin; SDH, succinate dehydrogenase; SNP, single nucleotide polymorphism(s). JCEM is published monthly by The Endocrine Society (http://www. endo-society.org), the foremost professional society serving the endocrine community. in the sporadic development of MTC in both Spanish and English patients. We found no evidence that the presence of the H50R is strongly associated with the risk of sporadic MTC, although we did observe an association with age at diagnosis of MTC in Spanish H50R carriers that we did not find in English patients. Finally, we looked for evidence of CCH or any other thyroid disease in a panel of germ-line SDH (B or D) mutation carriers and found none. We conclude that SDHD variants do not constitute a risk factor for developing CCH or sporadic MTC. (J Clin Endocrinol Metab 90: 2127–2130, 2005) units and has been found altered (as indeed have both the SDHB and SDHC genes) in both paraganglioma and pheochromocytoma (PCC) families (7–9). The authors found that the three affected members of the family had the variant c.149A⬎G (H50R), an alteration with controversial significance that has been related to both Merkel cell carcinomas and midgut carcinoids (10). Contrary to its apparently pathogenic character, the H50R variant has been found in 3% of two distinct control populations (11, 12). Moreover, it has been recently demonstrated that this alteration does not affect the activity of the SDHD protein (13). The goal of this analysis was to study the involvement of SDHD and related genes in non-RET CCH using three approaches: 1) screening these genes for abnormalities in nonRET CCH families; 2) performing an association study in MTC; and 3) investigating evidence of raised calcitonin levels in individuals carrying either the H50R variant or SDH mutations. Subjects and Methods Subjects Informed consent was obtained from all patients. CCH families. We studied the presence of mutations in SDH genes in all affected and nonaffected members of two CCH families (F1 and F2) who 2127 2128 J Clin Endocrinol Metab, April 2005, 90(4):2127–2130 Cascon et al. • SDH Variants, C Cell Hyperplasia, and MTC tested negative for mutations in RET (exons 1–20). RET gene segregation with the disease was studied in both families by means of haplotype analysis, using intragenic single nucleotide polymorphisms (SNP) located in exons 2 (rs1800858), 7 (rs1800860), 11 (rs179939), and 15 (rs1800863). We also studied SDHD segregation by using three SNPs (rs10789859, rs3839946, and rs7944155) that were chosen using PupaSNP, available at http://pupasnp.bioinfo.cnio.es/, and HapMap, available at http://www.hapmap.org. The proband of F1 was surgically operated for MTC in 1984, and he has 12 relatives with elevated basal calcitonin (BC) or pentagastrin-provoked (PG) calcitonin levels. Total prophylactic thyroidectomy was performed on 10 of these relatives, and CCH has been confirmed in nine of these cases by means of pathological studies (Table 1). The proband’s mother in F2 was diagnosed and operated for MTC in 1982. Subsequently, four relatives showed elevated BC or PG calcitonin levels, and three of them underwent prophylactic thyroidectomy (Table 1). Sporadic MTC patients. We studied the H50R variant in both Spanish and English patients. All Spanish (n ⫽ 120) and English (n ⫽ 135) MTC patients previously tested negative for mutations in RET by means of sequencing of exons 10, 11, and 13–16. No patients had a family history. SDH (B or D) mutation carriers. Thyroid pathology was excluded in all cases by evaluating the BC level and, in some cases, by ultrasound scan, although CCH is difficult to exclude using these methods. Controls. A set of 319 controls were selected from a larger group (up to 382) of unrelated and nonaffected individuals representative of the Spanish population. The Spanish control population (...truncated)