Abstract 1844: No evidence for genetic factor increasing renal cell cancer risk in Hereditary Leiomyomatosis and Renal Cell Cancer syndrome

Abstract

Abstract Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a hereditary tumor predisposition syndrome with fumarate hydratase (FH), which encodes a tricarboxylic acid cycle enzyme fumarase, as the predisposing gene. The HLRCC family members carry heterozygous germline mutations of the FH gene and the tumors often harbor a second hit making the growth fumarase deficient. The phenotype includes benign cutaneous and uterine leiomyomas as well as renal cell cancer (RCC). The HLRCC related RCCs usually belong to histological papillary type II subtype and are solitary, unilateral and aggressive. The benign leiomyomas are the most common manifestation of the syndrome affecting almost all FH mutation carriers whereas the renal cell cancer phenotype affects only about 20% of the HLRCC families. Interestingly, majority of the families with multiple renal cell cancer cases have concentrated in Finland and the U.S. Why the malignant phenotype affects only a part of the HLRCC patients is unknown. There is no genotype-phenotype correlation and type or site of the FH mutation does not affect the phenotype. The fumarase enzyme activity levels do not correlate with the phenotype either. Thus it is possible that the appearance of RCC requires, in addition to FH mutation, another genetic factor. To search for such a factor in four Finnish HLRCC families with multiple RCC cases we performed genome wide linkage and/or identical by descent (IBD) analyses. After finemapping procedures the only region compatible with linkage was the FH locus itself in 1q43. The genes of the region were screened but no pathognomonic mutations were found. Although these results do not exclude the existence of a genetic RCC risk modifier in HLRCC, the role of FH mutations behind RCC tumors is emphasized. Counseling and genetic testing should be available for HLRCC family members and the FH mutation carriers should be carefully followed up to enable early detection and treatment of the aggressive cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1844.