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PubMed2001

Germline mutation of dihydropyrimidine dehydrogenese gene among a Japanese population in relation to toxicity to 5-Fluorouracil.

5-Fluorouracil (5FU) is most commonly used in chemotherapy for human malignancy. Over 80% of administered 5FU is metabolically degraded by dihydropyrimidine dehydrogenase (DPD), a primary and rate-limiting enzyme in the 5FU metabolic pathway. A DPD-deficient phenotype among cancer patients, which has posed a serious problem in 5FU-based chemotherapy, was reported to be in part ascribed to germline mutations in dihydropyrimidine dehydrogenase (DPYD) gene. Therefore, we for the first time examined the frequencies and types of germline mutations in the DPYD gene among a total of 107 Japanese cancer patients and healthy volunteers. Of 214 alleles examined among them, 181 alleles were of the same type, which was assigned as wild type; 21 alleles revealed a nucleotide substitution resulting in silent mutation; and the remaining 12 alleles showed five types of nucleotide deletion or substitutions resulting in one frameshift and four missense mutations. Three of them, A74G, 812delT and L572V, were novel mutations. None of the study subjects showed homozygous frameshift or missense mutated alleles. We also studied the association between toxic response to 5FU and heterozygous frame shift or missense mutation of the DPYD gene among eight cancer patients who had received 5FU-based chemotherapy. These patients did not show any adverse effects higher than grade 3, suggesting that heterozygotes are not associated with increased toxicity to 5FU. Our results indicate that a very small percentage, about 0.2%, of the Japanese population seems to carry homozygous mutations in DPYD gene, mutations which possibly indicate genetically increased toxicity of 5FU-based chemotherapy.

Antimetabolites, Antineoplastic↗

PubMed1997

BRCA1 and BRCA2 Germline Mutations in Japanese with Hereditary Breast Cancer Families.

We examined germline mutations in BRCA1 and BRCA2 in 23 Japanese breast cancer families, using PCR-SSCP analysis. The same nonsense mutation (exon 5, Leu63ter) of BRCA1 was detected in two defferent families. Three different mutations resulting in a truncated BRCA2 protein (exon 9, 20, 24) were detected in three different families, including one male case of breast cancer. One base substitution mutation in BRCA2, A10462G, was detected in the other two families. Although the mean age of onset for breast cancer in families with the BRCA1-mutation was 50 years, the age of onset in families with the BRCA2-mutation was from 28 to 43 years. Among the 23 families examined, two families had members with ovarian cancers, three had members with prostate cancers, and one had a pancreatic cancer. However, none of these families was positive for the BRCA1 orBRCA2 mutation. Histopathologically, we observed a prevalence of histological grade 3 in BRCA1/2-associated familial breast cancers, because of nuclear atypia, structural atypia and mitotic activity. It is suggested that BRCA2 may play a more important role than BRCA1 in Japanese familial breast cancers, and these mutations are related to the aggressive nature and highly proliferative activity of the tumors.

Journal Article↗

PubMed1994

Germline mutations in the neurofibromatosis type 2 tumour suppressor gene.

The recent identification of the NF2 tumour suppressor gene has enabled large scale screening for pathological mutations in the gene. We have sought germline mutations in the NF2 gene by SSCP and heteroduplex analysis of cDNA and genomic DNA samples followed by cloning and sequencing of mutant alleles. In the present report we describe 11 putative pathological mutations, including five nonsense mutations, three short insertions or deletions causing frameshifts and three missense mutations. Most stop mutations and frameshift mutations were found in individuals expressing a severe phenotype while one of the three missense mutations was associated with a mild phenotype. Four unrelated NF2 patients of the 93 tested were found to have identical nonsense mutations caused by a C to T transition (C169) in a CpG dinucleotide, which is a potential mutational hotspot in the NF2 tumour suppressor gene.

Base Sequence↗

PubMed1996

Detection of RB germline mutations using exon-by-exon heteroduplex analysis compared with SSCP.

PURPOSE: To compare heteroduplex analysis with SSCP and to develop a simple and effective method for mutational screening of RB gene. MATERIALS AND METHODS: Leukocyte DNA was prepared from 12 unrelated Japanese patients with hereditary retinoblstoma. PCR combined with simultaneous nonisotopic heteroduplex and SSCP analysis was used to screen leukocyte DNA for such mutations, exon-by-exon, without the use of restriction endonuclease digestion. PCR was conducted using 28 pairs of primers flanking all 27 exons and the promoter region of the RB gene, with PCR products ranging from 159bp to 326bp. Mutations were identified by sequencing. RESULTS: Heterozygous germline mutations were detected in 8 of 12 Japanese patients. The mutations were identified by sequencing as follows: G-->C/acceptor of exon 11, T insertion/codon 389, C-->T/codon 455, 33bp insertion/codon 455 (C decreases GA), G-->T/codon 533, C-->T/codon 579, C deletion/codon 674, and C-->T/codon 787. CONCLUSION: Our results suggest that small RB gene mutations are common. Heteroduplex analysis has advantage over SSCP and they may complement each other for the rapid detection of unknown mutations.

DNA, Neoplasm↗

PubMed1998

Germline mutations of the PTEN/MMAC1 gene in Japanese patients with Cowden disease.

Cowden disease (CD) is an autosomal dominant disorder which confers a high susceptibility to diverse benign and malignant tumors. The PTEN/MMAC1 gene was identified as being responsible for CD, since its germline mutations have been identified in affected individuals in the United States and Europe. We identified three novel germline PTEN mutations, a 2-bp deletion, a 1-bp insertion and a missense mutation, in three of five Japanese patients with CD. The missense mutation resided outside of the region encoding a putative phosphatase domain of the predicted PTEN protein, where previously reported missense mutations in CD patients have been clustered. The present result suggests that a wide range of germline PTEN mutations may play a role in the pathogenesis of CD.

Female↗

PubMed2006

BRCA1 and p53 protein expression in cultured ovarian surface epithelial cells derived from women with and without a BRCA1 germline mutation.

AIM: Mutations in the BRCA1 and TP53 genes are early genetic events leading to (hereditary) ovarian carcinoma. The human ovarian surface epithelium (OSE) is considered the tissue of origin of at least a subset of these tumours. Therefore, OSE cell cultures derived from women harbouring BRCA1 germline mutations can be a potential model to study hereditary ovarian carcinogenesis. In fact, previous in vitro studies indicate phenotypical differences between OSE from women with and without such germline mutations. Therefore, we have assessed whether differences in the expression of BRCA1 and p53 proteins in cultured OSE cells could contribute to these observations. STUDY DESIGN: Thirty-two OSE cultures derived from women harbouring a BRCA1 mutation (Predisposed OSE [POSE]) and ten cultures from women without a cancer predisposition (Non predisposed OSE [NPOSE]) were grown under standard conditions. Immunocytochemistry was performed to assess the expression of the BRCA1- and p53 proteins. Ki67 immunocytochemical expression was assessed to determine possible differences in cell cycle status between the two groups. In addition, to study whether wild type p53 was expressed, induction of p53 by cis-platinum was assessed by Western blot. RESULTS: On the basis of Ki67 expression, three different groups were analyzed. In the group with all cultures that expressed Ki67 no significant difference was observed in BRCA1 (P = 0.19) and p53 expression (P = 0.09). In the group with moderate to high Ki67 expression no difference in BRCA1 expression (P = 0.50) was observed. However, p53 expression was significantly lower in the case group (P = 0.01). The same observation for p53 was made in the group with only high Ki67 expression (P = 0.02). Furthermore, the expression of both BRCA1 and p53 positively correlates with Ki67 expression. In POSE and NPOSE, p53 was induced by cis-platinum to a similar extent. CONCLUSION: Our study indicates differences in the expression of p53, but not in the expression of BRCA1 between POSE and NPOSE. In addition, our findings do suggest the absence of losses of the wild type BRCA1 and p53 genes in the studied OSE cultures. This indicates that losses in these genes cannot account for observed differences in phenotypical traits between POSE and NPOSE, but that differences in levels of p53 might contribute.

Adult↗

PubMed2004

A TP53-truncating germline mutation (E287X) in a family with characteristics of both hereditary diffuse gastric cancer and Li-Fraumeni syndrome.

Mutations in CDH1, which encodes E-cadherin, have been associated with hereditary diffuse gastric cancer (HDGC) in Western populations but have not been shown to play a major role in Asians. Recently, a patient with familial gastric cancer (FGC) was shown to harbor a germline mutation in the TP53 gene, which encodes p53 and has been previously associated with Li-Fraumeni Syndrome (LFS). To determine whether mutations in TP53 are associated with FGC in Asians, we screened the entire coding region of TP53 in probands from 23 Korean FGC families. We identified a nonsense (E287X) TP53 germline mutation in a family whose history is compatible with both HDGC and LFS. Two members of this family (SNU-G2) were afflicted with brain tumors, seven with gastric cancers, two with sarcomas, and one with both gastric cancer and a sarcoma. The E287X TP53 mutation segregated with the cancer phenotype in the family members from whom DNA samples were available. To our knowledge, this is the first report of a large family with both HDGC and LFS. Our results suggest that TP53 mutational screening in FGC families should be interpreted with caution because additional TP53 mutation-carrying HDGC families may also show LFS-related phenotypes.

Base Sequence↗

PubMed2002

Phenotypic variation in eight extended CDKN2A germline mutation familial atypical multiple mole melanoma-pancreatic carcinoma-prone families: the familial atypical mole melanoma-pancreatic carcinoma syndrome.

BACKGROUND: Hereditary pancreatic carcinoma shows extant phenotypic and genotypic heterogeneity as evidenced by its integral association with a variety of hereditary cancer syndromes inclusive of the familial atypical multiple mole melanoma (FAMMM) syndrome in concert with CDKN2A (p16) germline mutations. METHODS: Creighton University's familial pancreatic carcinoma resource comprises 159 families of which 19 (12%) show the FAMMM cutaneous phenotypes. The authors describe eight families with the FAMMM-pancreatic carcinoma (FAMMM-PC) association in concert with a CDKN2A germline mutation. Each family was thoroughly educated about all facets of the study, including the molecular genetics, reduced penetrance of CDKN2A mutations, and their variable expressivity. Genetic counseling was provided to each patient. RESULTS: Diversity in cancer presentation within and among the families was noteworthy, wherein melanoma predominated in certain of the families whereas pancreatic carcinoma predominated in others. Early-onset pancreatic carcinoma (at ages 35, 45, 46, and 49 years) appeared in some of the families whereas markedly later-onset pancreatic carcinoma occurred in others. There were four incidences of melanoma and pancreatic carcinoma as double primaries in the same individuals. One patient with melanoma and pancreatic carcinoma had a third primary of breast carcinoma. Another patient had sarcoma, esophageal carcinoma, and two melanoma primaries, whereas his daughter had sarcoma and was a carrier of a CDKN2A mutation. CONCLUSIONS: The authors suggest that these tumors may collectively, in concert with CDKN2A mutations, constitute a "new" putative hereditary carcinoma syndrome referred to as FAMMM-PC. More clinical and molecular genetic research on additional families with pancreatic carcinoma in concert with the FAMMM will be required.

Adult↗

PubMed2004

Germline mutation analysis of the androgen receptor gene in Finnish patients with prostate cancer.

PURPOSE: Steroid hormones, particularly androgens, are suspected to have a major role in prostate carcinogenesis. Since androgen receptor mediates androgenic effects on cells and recent studies suggest that the androgen receptor gene is a putative prostate cancer susceptibility locus, we screened the coding region of the androgen receptor gene for germline mutations using the genomic DNA of patients with prostate cancer. MATERIALS AND METHODS: DNA samples from 38 patients with early onset prostate cancer and 36 from Finnish prostate cancer families showing no male-to-male transmission of prostate cancer were analyzed for mutations in the androgen receptor gene using single strand conformation polymorphism analysis and subsequent sequencing. RESULTS: R726L substitution in the hormone binding region of androgen receptor was found in 1 prostate cancer family but no previously uncharacterized germline mutations were detected. CONCLUSIONS: Our results indicate that constitutional androgen receptor mutations explain only a small fraction of familial and early onset prostate cancer cases in Finland.

Aged↗

PubMed1998

Germline mutations in the vhl gene in patients presenting with phaeochromocytomas.

It has been shown that an appreciable percentage of patients presenting with primary, apparently sporadic phaeochromocytomas may in fact have von-Hippel-Lindau (VHL) disease. In order to investigate this, we retrospectively screened 68 patients, who had been operated on for phaeochromocytomas, for the presence of germline mutations in the vhl gene. DNA was isolated from peripheral-blood leukocytes and used to screen the entire coding sequence and the intron-exon boundaries of the vhl gene for mutations, using a PCR-based SSCP strategy. When an abnormal pattern was found in the SSCP analysis, sequence analysis was carried out. We found SSC variants in the vhl gene in 8 of the 68 patients. Of 6 patients, 2 turned out to be related (an uncle and his nephew), and they carried the same mis-sense mutation: R64P. In 4 other patients, mis-sense mutations, P25L, L63P, G144Q and I147T, were also identified. None of these mutations has been described, and 3 of them (P25L, L63P and R64P) are located closer to the N terminus of the vhl protein than any reported vhl mutation. In the remaining 2 cases, the mutations were localized not in the coding sequence but in the intronic sequence (but not within splice-sites), adjacent to the exon, so they were probably not related to the disease. Our results show that a relatively high proportion (6/68, or 8.8%), though not as high as the 20% reported earlier, of patients with apparently sporadic phaeochromocytomas may carry germline mutations in the vhl gene.

Adrenal Gland Neoplasms↗

PubMed2026

Heterozygous germline mutations in MSH3, and probably MLH3, act as classical tumour suppressors, leading to excess somatic deletion mutations, signature ID4 and increased colorectal cancer risk.

BACKGROUND: MSH3 and MLH3 are non-canonical DNA mismatch repair genes, involved in repairing insertion-deletion mutations. Colorectal cancer (CRC) and adenomas have been reported in patients with bi-allelic germline MSH3 mutations, and in a very few bi-allelic MLH3 mutation carriers. OBJECTIVES: We hypothesised that germline loss-of-function MSH3 and MLH3 mutations were akin to constitutional mismatch repair deficiency (cMMRd) and Lynch syndrome, such that CRC could result from either bi-allelic germline mutations or heterozygous germline mutations after second hits. DESIGN: About 12 000 CRC and multiple polyp cases and 460 000 controls were studied. 2023 patients underwent cancer genome sequencing. RESULTS: One CRC/multiple polyp case had bi-allelic MSH3 mutations and another, bi-allelic MLH3 mutations. MSH3 and MLH3 germline heterozygotes had an increased risk of CRC (2.2-fold, p=6.6×10-5 and 1.6-fold, p=0.028, respectively), owing to somatic 'second hits' that inactivated the wildtype allele. Single second hits sometimes inactivated both MSH3 and the nearby APC gene. All CRCs with MSH3 or MLH3 deficiency were microsatellite-stable but hypermutant. Deletions of ≥2 bp were particularly increased (~12-fold) and signature ID4 was usually present (p<0.0001). CRCs from heterozygotes without 'second hits' showed no hypermutation. CONCLUSION: The phenotypes of bi-allelic MSH3 and MLH3 mutation carriers resemble some patients with cMMRd. Heterozygous germline MSH3 and MLH3 alleles have incomplete penetrance, but increase CRC risk via hypermutation, phenotypically resembling PMS2-mutant Lynch syndrome. A causal association with specific mutations has not previously been reported for ID4 in human tumours. ID4 probably does not have a single aetiology, but can result from MSH3 or MLH3 deficiency.

COLONIC POLYPS↗

PubMed2001

Sporadic multiple primary melanoma cases: CDKN2A germline mutations with a founder effect.

Multiple primary cancers are one of the hallmarks of inherited predisposition. Outside the familial context, multiple primary tumors could be related either to germline de novo mutations or to low-penetrance mutations, in predisposing genes. We selected 100 patients who displayed multiple primary melanoma (MPM) without any known melanoma cases recorded within their families and looked for germline mutations in the two melanoma-predisposing genes identified to date, CDKN2A and CDK4 exon 2. Nine patients (9%) had germline mutations in CDKN2A, whereas none carried germline mutations in exon 2 of CDK4. Seven cases displayed a recurrent missense mutation, G101W, already described in more than 20 melanoma-prone families; one case carried a missense mutation never reported to date (P114S), and the last case was a carrier of a 6 bp insertion at nucleotide 57 resulting in a duplication of codons 18 and 19. To ascertain whether the G101W was a mutational hot spot for de novo mutations or a common founder mutation, we genotyped eight microsatellite markers flanking the CDKN2A gene. After allowing for recombination over time, haplotype sharing provided evidence for an original G101W mutation common to 6 out of 7 sporadic MPM cases. Therefore, it can be concluded that de novo germline CDKN2A mutations associated with MPM are rare.

Adult↗

PubMed1999

STK11/LKB1 germline mutations are not identified in most Peutz-Jeghers syndrome patients.

Germline mutations of the STK11 gene mapped to chromosome 19p13.3 are responsible for Peutz Jeghers syndrome (PJS), a dominant disorder associated with characteristic gastrointestinal hamartomatous polyps and a predisposition to various cancers. We conducted a detailed investigation of germline STK11 alterations by protein truncation test and genomic DNA sequence analysis in ten unrelated PJS families. We identified a novel truncating deletion spanning STK11 exons 2-7 in a single patient and several known polymorphisms. Loss of heterozygosity studies in PJS polyps of four of these patients identified an allelic deletion of D19S886 in another patient. Our results suggest that STK11 mutations account for only a proportion of PJS cases.

AMP-Activated Protein Kinase Kinases↗

PubMed2005

Spectrum and prevalence of BRCA1 and BRCA2 germline mutations in Sardinian patients with breast carcinoma through hospital-based screening.

BACKGROUND: Factors that are predictive of carrying BRCA1 and BRCA2 germline mutations in patients with breast carcinoma are awaited widely. The genetically homogeneous Sardinian population may be useful for defining the role of such genetic alterations further through a clinical evaluation program. METHODS: One hundred two of 659 patients with breast carcinoma (15.5%) who were collected consecutively had a family history of breast carcinoma and were screened for BRCA1/2 mutations by denaturing high-performance liquid chromatography and DNA sequencing. RESULTS: Three deleterious germline BRCA1/2 mutations were detected in 15 of 102 families (14.7%), including 13 families (86.7%) with BRCA2 mutations and 2 families (13.3%) with BRCA1 mutations. A single variant, BRCA2-8765delAG, was the most recurrent mutation in the series and was found in 12 of 102 families (11.8%) and in 18 of 657 patients (2.7%). The average age at diagnosis was significantly younger in families with BRCA1/2 mutations (48.6 yrs) compared with the age of patients who had no detectable mutation (52.9 yrs; P = 0.039). Moreover, BRCA1/2 mutations were found at a significantly higher rate in families who had at least 1 member with ovarian carcinoma or male breast carcinoma (5 of 12 families; 41.7%) than in families without such an association (10 of 90 families; 11.1%; P = 0.003). CONCLUSIONS: BRCA2 mutations were approximately 6 times more prevalent than BRCA1 mutations. A diagnosis of breast carcinoma before age 50 years, ovarian carcinoma, male breast carcinoma, and 3 affected generations all were associated significantly with BRCA1/2 mutations. Although the current findings provided further support for the hypothesis that additional breast carcinoma susceptibility genes remain to be identified, such indicators of the presence of BRCA1/2 mutations may be useful in counseling patients about undergoing genetic testing.

Adult↗

PubMed2004

Germline mutation of the LKB1/STK11 gene with loss of the normal allele in an aggressive breast cancer of Peutz-Jeghers syndrome.

Peutz-Jeghers syndrome (PJS) is an autosomal-dominant polyposis disorder with an increased risk of multiple cancer. The LKB1/STK11 gene, which acts as a tumor suppressor, is responsible for PJS and plays a role in suppressing breast cancer. The low expression of LKB1/STK11 in sporadic breast cancer is significantly associated with shorter survival. Here we describe a PJS patient with aggressive breast cancer that carried not only a germline mutation of LKB1/STK11 but also loss of the normal allele. The combination of these mutations may be associated with the poor prognosis of this patient. To our knowledge, we are the first to show that a germline mutation causing PJS is combined with the loss of the homologous normal allele of LKB1/STK11 in breast cancer.

AMP-Activated Protein Kinase Kinases↗

PubMed2004

A screen for germline mutations in the gene encoding CCCTC-binding factor (CTCF) in familial non-BRCA1/BRCA2 breast cancer.

INTRODUCTION: The CCCTC-binding factor (CTCF), known as a versatile transcription factor and chromatin insulator and to be involved in X inactivation, has also been suggested to be a tumour suppressor on 16q. We investigated 153 patients with familial non-BRCA1/BRCA2 breast cancer for germline mutations in the CTCF gene. METHODS: Mutation screening of CTCF was performed by denaturing high-performance liquid chromatography followed by cycle sequencing. RESULTS: We found two sequence variants, 240G-->A in the 5' untranslated region and 1455C-->T (S388S) in exon 4, in five familial breast cancer cases. Three of these five cases had both variants. Cases and controls showed the same prevalence for the two variants, which were found in linkage disequilibrium in most cases and controls. CONCLUSION: The present study suggests that germline mutations in CTCF are not important as a risk factor for breast cancer.

5' Untranslated Regions↗

PubMed2006

Microsatellite stable colorectal cancers in clinically suspected hereditary nonpolyposis colorectal cancer patients without vertical transmission of disease are unlikely to be caused by biallelic germline mutations in MYH.

Microsatellite analysis and immunohistochemistry are commonly used initial screening tests for hereditary nonpolyposis colorectal cancer. However, tumors in roughly one-half of the patients fulfilling the Bethesda guidelines are microsatellite stable. In addition, normal mismatch repair protein expression in these tumors suggests that a defect in the mismatch repair system is unlikely. Because biallelic MYH mutations occur in patients with both high and low numbers of adenomas, we hypothesized that MYH is involved in the tumorigenesis of microsatellite stable colorectal cancers in patients without vertical transmission of disease and who fulfill the Bethesda guidelines. MYH was analyzed in 50 cancer patients and 116 healthy controls by complete genomic DNA sequencing. No biallelic germline mutations were identified. One patient was a heterozygous carrier for the p.G382D missense mutation, and another patient was a heterozygous carrier for the novel missense mutation p.Q484H. We identified six common variants, three in the coding region (p.V22M, p.Q324H, and p.S501F) and three in adjacent intronic regions (c.157+30A>G, c.462+35G>A, and c.1435-40G>C). In summary, biallelic germline mutations of MYH are unlikely to cause colorectal cancer in patients sharing clinical features with hereditary nonpolyposis colorectal cancer families without mismatch repair defect and therefore cannot fill the molecular diagnostic gap in this subgroup of Bethesda-positive patients.

Adult↗

PubMed2000

A germline mutation at the extreme 3' end of the APC gene results in a severe desmoid phenotype and is associated with overexpression of beta-catenin in the desmoid tumor.

Desmoid tumors arise sporadically or as part of the extraintestinal manifestations of familial adenomatous polyposis (FAP). In FAP, two distinct clinical presentations of the desmoid phenotype are seen: 1) one or a few desmoid tumors present predominantly in the abdominal wall or the abdomen; 2) a florid proliferation of tumors early in life, mostly near the axial skeleton or extremities. These different phenotypes have been associated with different sites of germline mutations in the adenomatous polyposis coli gene (APC gene). We present a large, French-Canadian kindred with a florid desmoid tumor phenotype caused by a germline mutation at codon 2643-2644 of the APC gene. The phenotype was characterized by the early onset of multiple tumors, arising near the axial skeleton and in proximal extremities. The penetrance of desmoid tumors was near 100% in this kindred. However, the expression of the disease was variable amongst the different affected relatives. Many gene carriers had cutaneous cysts. Polyposis of the colon was rarely observed in the affected individuals and we did not document upper gastro-intestinal polyps. The mutant APC allele did not express a stable truncated protein in vivo. Molecular analysis of the proband's tumor DNA revealed a somatic inactivating mutation of the wild-type allele. Immunohistochemistry on the tumor also demonstrated elevated levels of beta-catenin. The present study demonstrates that this extreme 3' APC mutation is associated with a severely penetrant desmoid phenotype and attenuated polyposis coli. It also suggests the involvement of the beta-catenin pathway in the development of desmoid tumors in FAP. The natural history of the disease is variable between individuals, and surgical interventions have to be timed appropriately due to the frequent recurrences.

3' Untranslated Regions↗