Novel FH mutations in families with hereditary leiomyomatosis renal cell cancer (HLRCC) and in patients with isolated type 2 papillary renal cell carcinoma

International audienceBackground Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant disorder predisposing humans to cutaneous and uterine leiomyomas; in 20% of affected families, type 2 papillary renal cell cancers (PRCCII) also occur with aggressive course and poor prognosis. HLRCC results from heterozygous germline mutations in the tumor suppressor fumarate hydratase (FH) gene. Methods As part of the French National Cancer Institute (INCa) "Inherited predispositions to kidney cancer" network, we performed sequence analysis and a functional study of FH in 56 families with clinically proven or suspected HLRCC and in 23 patients with isolated PRCCII (5 familial and 18 sporadic). Results We identified 32 different germline FH mutations (15 missense, six frameshifts, four nonsense, one deletion/insertion, five splice site and one complete deletion) in 40/56 (71.4%) families with proven or suspected HLRCC and in 4/23 (17.4%) probands with PRCCII alone, including 2 sporadic cases. Twenty-one of these were novel and all were demonstrated as deleterious by significant reduction of FH enzymatic activity. In addition, five asymptomatic parents in three families were confirmed as carrying disease-causing mutations. Conclusions This study identified and characterized 21 novel FH mutations and demonstrated that PRCCII can be the only one manifestation of HLRCC. Due to the incomplete penetrance of HLRCC, we propose to extend the FH mutation analysis to every patient with PRCCII occurring before 40 yrs of age or when renal tumor harbors characteristic histologic features, in order to discover previously ignored HLRCC-affected families