Mutation screening of fumarate hydratase by multiplex ligation-dependent probe amplification: detection of exonic deletion in a patient with leiomyomatosis and renal cell cancer.

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a syndrome predisposing to cutaneous and uterine leiomyomatosis as well as renal cell cancer and uterine leiomyosarcoma. Heterozygous germline mutations in the fumarate hydratase (FH, fumarase) gene are known to cause HLRCC. On occasion, no FH mutation is detected by direct sequencing, despite the evident HLRCC phenotype in a family. In the present study, to investigate whole gene or exonic deletions and amplifications in FH mutation-negative patients, we used multiplex ligation-dependent probe amplification technology. The study material comprised 7 FH mutation-negative HLRCC patients and 12 patients affected with HLRCC-associated phenotypes, including papillary RCC, early-onset RCC, uterine leiomyomas, or uterine leiomyosarcoma. A novel FH mutation, a deletion of FH exon 1 that encodes the mitochondrial signal peptide, was detected in one of the HLRCC patients (1/7). The patient with the FH mutation displayed numerous painful cutaneous leiomyomas and papillary type renal cell cancer. Our finding, together with the two patients with whole FH gene deletion who had been detected previously, suggests that exonic or whole-gene FH deletions are not a frequent cause of HLRCC syndrome.

NOD2 3020insC alone is not sufficient for colorectal cancer predisposition.

Mutations in NOD2 have been shown to associate with increased susceptibility to Crohn's disease. A recent Polish study linked the truncating NOD2 3020insC variant with an increased risk of colorectal cancer (CRC) at an older age (>50 years) of disease onset, with an odds ratio of 2.23. We studied the possible contribution of the 3020insC variant to CRC risk in a series of 1,042 Finnish population-based patients from which 926 samples were successfully analyzed and in 348 anonymous cancer-free controls. The frequency of the 3020insC mutation was 3.7% in both CRC patients (34 of 926, including 1 homozygote) and cancer-free controls (13 of 348; odds ratio, 0.98; confidence interval, 0.51-1.88). Contrary to the Polish study, there was no significant difference in the mutation rates between CRC patients > 50 years of age (25 of 576; 4.3%) and controls in the present series. We studied respective tumor tissue DNAs of all patients displaying heterozygous 3020insC changes for loss of heterozygosity. Loss of heterozygosity at NOD2 was observed in only 1 of the 33 CRC samples. Our results suggest that NOD2 3020insC alone does not contribute to CRC risk. If this variant predisposes to CRC, additional factors not present in the Finnish population need to be involved.