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Biomedical subjects

Charis Eng

Publications and source records attributed to Charis Eng.

At least 91 records · Page 5Linked to original sources
PubMed2003

BMP2 exposure results in decreased PTEN protein degradation and increased PTEN levels.

The tumour suppressor gene PTEN encodes a dual-specificity phosphatase that recognizes protein and phosphatidylinositiol substrates and modulates cellular functions such as migration and proliferation. Germline mutations of PTEN have been shown to cause Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome and Proteus syndrome. Recently, germline mutations in BMPR1A, the gene encoding the type 1A receptor of bone morphogenetic proteins (BMP) have been found in rare families with Cowden syndrome, suggesting that there may be a link between BMP signaling and PTEN. We thus sought to determine whether BMP2 stimulation alters PTEN protein levels in the breast cancer line, MCF-7. We found that exposure to BMP2 increased PTEN protein levels in a time- and dose-dependent manner. The increase in PTEN protein was rapid and was not due to an increase in new protein synthesis, as cycloheximide treatment did not inhibit BMP2-induced PTEN accumulation, suggesting that BMP2 stimulation inhibited PTEN protein degradation. Indeed, we found that BMP2 treatment of MCF-7 cells decreased the association of PTEN with two proteins in the degradative pathway, UbCH7 and UbC9. These data indicate that BMP2 exposure can regulate PTEN protein levels by decreasing PTEN's association with the degradative pathway. This opens up a new mode of regulating PTEN activity to be investigated further and may explain why BMPR1A can act as a minor susceptibility gene for PTEN mutation negative Cowden syndrome.

Blotting, Western↗
PubMed2003

Peroxisome proliferator-activated receptor gamma-mediated differentiation: a mutation in colon cancer cells reveals divergent and cell type-specific mechanisms.

Activation of the nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma) inhibits cell growth and induces differentiation in both adipocyte and epithelial cell lineages, although it is unclear whether this occurs through common or cell-type specific mechanisms. We have identified four human colon cancer cell lines that do no undergo growth inhibition or induce markers of differentiation after exposure to PPARgamma agonists. Sequence analysis of the PPARgamma gene revealed that all four cell lines contain a previously unidentified point mutation in the ninth alpha-helix of the ligand binding domain at codon 422 (K422Q). The mutant receptor did not exhibit any defects in DNA binding or retinoid X receptor heterodimerization and was transcriptionally active in an artificial reporter assay. However, only retroviral transduction of the wild-type (WT), but not mutant, receptor could restore PPARgamma ligand-induced growth inhibition and differentiation in resistant colon cancer cell lines. In contrast, there was no difference in the ability of fibroblast cells expressing WT or K422Q mutant receptor to undergo growth inhibition, express adipocyte differentiation markers, or uptake lipid after treatment with a PPARgamma agonist. Finally, analysis of direct PPARgamma target genes in colon cancer cells expressing the WT or K422Q mutant allele suggests that the mutation may disrupt the ability of PPARgamma to repress the basal expression of a subset of genes in the absence of exogenous ligand. Collectively, these data argue that codon 422 may be a part of a co-factor(s) interaction domain necessary for PPARgamma to induce terminal differentiation in epithelial, but not adipocyte, cell lineages and argues that the receptor induces growth inhibition and differentiation via cell lineage-specific mechanisms.

Amino Acid Sequence↗
PubMed2003

Increased nuclear phosphatase and tensin homologue deleted on chromosome 10 is associated with G0-G1 in MCF-7 cells.

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor that causes cell cycle arrest. Lack of a nuclear locator sequence and a function in the cytosolic phosphatidylinositol 3'-kinase/Akt pathway diverted its study from the nucleus. However, immunohistochemistry revealed PTEN in the nucleus of normal cells and decreased nuclear PTEN in neoplastic tissues. Using protein expression analysis and fluoroscopic localization of green fluorescence protein-tagged PTEN, we examined nuclear PTEN in MCF-7 cells. We demonstrate that PTEN enters the nucleus and that nuclear PTEN varies throughout the cell cycle. Higher nuclear PTEN levels were associated with G0-G1 phase, and lower nuclear PTEN levels were associated with S phase. We postulate that nuclear PTEN activity might directly regulate the cell cycle.

Breast Neoplasms↗
PubMed2003

PTEN: one gene, many syndromes.

PTEN, on 10q23.3, encodes a major lipid phosphatase which signals down the phosphoinositol-3-kinase/Akt pathway and effects G1 cell cycle arrest and apoptosis. Germline PTEN mutations have been found to occur in 80% of classic Cowden syndrome (CS), 60% of Bannayan-Riley-Ruvalcaba syndrome (BRRS), up to 20% of Proteus syndrome (PS), and approximately 50% of a Proteus-like syndrome (PSL). CS is a heritable multiple hamartoma syndrome with a high risk of breast, thyroid, and endometrial carcinomas. BRRS is a congenital autosomal dominant disorder characterized by megencephaly, developmental delay, lipomatosis, and speckled penis. PS and PSL had never been associated with risk of malignancy. Finding germline PTEN mutations in patients with BRRS, PS, and PSL suggests equivalent risks of developing malignancy as in CS with implications for medical management. The mutational spectra of CS and BRRS overlap, with many of the mutations occurring in exons 5, 7, and 8. Genotype-phenotype association analyses have revealed that the presence of germline PTEN mutations is associated with breast tumor development, and that mutations occurring within and 5' of the phosphatase motif were associated with multi-organ involvement. Pooled analysis of PTEN mutation series of CS and BRRS occurring in the last five years reveals that 65% of CS-associated mutations occur in the first five exons encoding the phosphatase domain and the promoter region, while 60% of BRRS-associated mutations occur in the 3' four exons encoding mainly the C2 domain. Somatic PTEN mutations occur with a wide distribution of frequencies in sporadic primary tumors, with the highest frequencies in endometrial carcinomas and glioblastoma multiform. Several mechanisms of PTEN inactivation occur in primary malignancies derived from different tissues, but a favored mechanism appears to occur in a tissue-specific manner. Inappropriate subcellular compartmentalization and increased/decreased proteosome degradation may be two novel mechanisms of PTEN inactivation. Further functional work could reveal more effective means of molecular-directed therapy and prevention.

Abnormalities, Multiple↗
PubMed2003

A role for mitochondrial enzymes in inherited neoplasia and beyond.

Mitochondrial defects have been associated with neurological disorders, as well as cancers. Two ubiquitously expressed mitochondrial enzymes--succinate dehydrogenase (SDH) and fumarate hydratase (FH, fumarase)--catalyse sequential steps in the Krebs tricarboxylic-acid cycle. Inherited heterozygous mutations in the genes encoding these enzymes cause predispositions to two types of inherited neoplasia syndromes that do not share any component tumours. Homozygous mutations in the same genes result in severe neurological impairment. Understanding this link between inherited cancer syndromes and neurological disease could provide further insights into the mechanisms by which mitochondrial deficiencies lead to tumour development.

Apoptosis↗
PubMed2003

From developmental disorder to heritable cancer: it's all in the BMP/TGF-beta family.

Transforming growth factor-beta (TGF-beta) regulates many cellular processes through complex signal-transduction pathways that have crucial roles in normal development. Disruption of these pathways can lead to a range of diseases, including cancer. Mutations in the genes that encode members of the TGF-beta pathway are involved in vascular diseases as well as gastrointestinal neoplasia. More recently, they have been implicated in Cowden syndrome, which is normally associated with mutations in the phosphatase and tensin homologue gene PTEN. Molecular studies of TGF-beta signalling are now showing why mutations in genes that encode components of this pathway result in inherited cancer and developmental diseases.

Animals↗
PubMed2003

Genetic analysis of mitochondrial complex II subunits SDHD, SDHB and SDHC in paraganglioma and phaeochromocytoma susceptibility.

BACKGROUND: Germline mutations in three subunits of mitochondrial complex II (SDHB, SDHC and SDHD) may be associated with susceptibility to phaeochromocytoma (PC) and/or head and neck paraganglioma (HNPGL). METHODS: To further define the role of SDH subunit mutations in these disorders, we analysed a series of 22 probands with PC and evidence of genetic susceptibility (seven with familial PC only, one with familial PC and HNPGL, 10 sporadic cases with multiple PC and four cases of isolated paediatric onset PC) for germline SDHB, SDHC and SDHD mutations. In addition, we analysed 34 cases of HNPGL (30 isolated cases with single tumours, three isolated cases with multiple tumours and one familial case with multiple tumours) for somatic and germline mutations in SDHB, SDHC and SDHD. RESULTS: We identified four germline mutations (three SDHB and one SDHD, three novel) in the 22 PC probands. Combining these results with our previous series, we have detected germline SDHB or SDHD mutations in 2/12 (17%) of familial PC only kindreds, 4/5 (80%) of familial PC and HNPGL cases, 1/10 of sporadic multiple PC cases and 2/4 (50%) of paediatric PCs. No somatic mutations were detected in the HNPGL tumours, but four cases with multiple HNPGL had the common P81L germline SDHD mutation. Intriguingly a silent SNP (c.204C > T) in SDHD was significantly more common in HNPGL cases (6/34) than in controls (1/100, P = 0.0011). Combining our results with those from two other large studies in which both SDHB and SDHD have been analysed, SDHB mutations were most commonly associated with phaeochromocytoma susceptibility and SDHD with the development of HNPGL (P = 0.025). However, germline SDHB and SDHD mutations demonstrate considerable phenotypic variability and genotype-phenotype correlations are complex. CONCLUSION: The significantly lower frequency (P = 0.028) of germline SDH subunit mutations in familial PC only cases compared to those with familial PC and HNPGL suggests that further PC susceptibility gene(s) remain to be identified.

Adolescent↗
PubMed2003

GI polyposis and glycogenic acanthosis of the esophagus associated with PTEN mutation positive Cowden syndrome in the absence of cutaneous manifestations.

A 62-yr-old man was referred for management of GI polyposis. Large bowel polyps were initially diagnosed >25 yr ago, and the patient had undergone multiple colonoscopies and polypectomies. Personal and family history were notable for thyroid goiter and hypothyroidism. Physical examination was notable for lingular papillomatosis. No cutaneous lesions were seen. Upper endoscopy revealed esophageal glycogen acanthosis. There were multiple polyps throughout the stomach and the small and large intestines. Histology of these polyps showed multiple cell types including juvenile polyps, inflammatory polyps with fibromuscular proliferation and lamina propria ganglion cells, and focal adenomatous change. A clinical diagnosis of Cowden syndrome was made. Mutation analysis revealed a variant in exon 8 of the PTEN gene. Direct sequencing revealed a germline heterozygous C.892-895InsA, which is predicted to result in a truncated PTEN protein. Cowden syndrome is an underdiagnosed, underrecognized, autosomal dominant, inherited syndrome. For the gastroenterologist, esophageal acanthosis and multiple hamartomatous polyps should suggest the diagnosis. Sensitive molecular diagnostic tests looking for mutations in the appropriate genes are clinically available. Together with genetic counseling, molecular diagnostic testing will allow more accurate risk assessment and surveillance for cancer for both the patient and family members.

Endoscopy↗
PubMed2003

Intronic single nucleotide polymorphisms in the RET protooncogene are associated with a subset of apparently sporadic pheochromocytoma and may modulate age of onset.

Approximately 75% of pheochromocytomas are sporadic. Germline mutations in RET, VHL, SDHB, and SDHD have been shown to cause the 25% that are hereditary. Germline high penetrance gain-of-function RET mutations cause multiple endocrine neoplasia type 2, of which medullary thyroid carcinoma (MTC) and pheochromocytoma are components, whereas loss-of-function mutations cause Hirschprung disease (HSCR). A low-penetrance founder locus, in linkage disequilibrium with a RET ancestral haplotype comprising specific alleles at three intron (IVS) 1 single nucleotide polymorphisms (SNPs) (haplotype 0) and SNP A45A, predisposes to the majority of isolated HSCR. A different low-penetrance locus, in linkage disequilibrium with IVS 1 haplotype 2 and SNP S836S, was associated with a subset of sporadic MTC. We, therefore, sought to determine whether RET might also be a low-penetrance gene for apparently sporadic pheochromocytoma. We analyzed 104 pheochromocytoma cases without germline mutations in RET, VHL, SDHD, and SDHB for their status at A45, S836, three IVS 1 SNPs, and a novel upstream insertion/deletion variant. Pheochromocytoma cases were not associated with either A45A or S836S, but we found that cases were associated with haplotype 0 (P = 0.032). However, unlike HSCR, this pheochromocytoma-associated haplotype 0 was not associated with A45A. Taken together with the strengthening of association with the addition of the 5' insertion/deletion variant data (P = 0.016), our observations suggest the presence of a low-penetrance pheochromocytoma susceptibility locus in a region upstream of the putative loci for HSCR and apparently sporadic MTC.

Adrenal Gland Neoplasms↗
PubMed2002

A founding locus within the RET proto-oncogene may account for a large proportion of apparently sporadic Hirschsprung disease and a subset of cases of sporadic medullary thyroid carcinoma.

Hirschsprung disease (HSCR) is a common congenital disorder characterized by aganglionosis of the gut. The seemingly unrelated multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant disorder characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism. Yet, germline mutations in the RET proto-oncogene are associated with both MEN 2 and HSCR. In the former, gain-of-function mutations in a limited set of codons is found, whereas, in the latter, loss-of-function mutations are found. However, germline RET mutation is associated with only 3% of a population-based series of isolated HSCR, and little is known about susceptibility to sporadic MTC. We have found previously that specific haplotypes comprising RET coding single-nucleotide polymorphisms (SNPs) comprising exon 2 SNP A45A were strongly associated with HSCR, whereas haplotypes associated with exon 14 SNP S836S were associated with MTC. In this study, we describe three novel intron 1 SNPs, and, together with the coding SNP haplotypes, the data suggest the presence of distinct ancestral haplotypes for HSCR and sporadic MTC in linkage disequilibrium with a putative founding susceptibility locus/loci. The data are consistent with the presence of a very ancient, low-penetrance founder locus approximately 20-30 kb upstream of SNP A45A, but the failure of the SNPs to span the locus presents challenges in modeling mode of transmission or ancestry. We postulate that this founding locus is germane to both isolated HSCR and MTC but also that different mutations in this locus would predispose to one or the other.

Alleles↗
PubMed2002

Frequent somatic mutations in PTEN and TP53 are mutually exclusive in the stroma of breast carcinomas.

We have recently shown that loss of heterozygosity of specific markers, including those at 10q23, 17p13-p15 and 16q24, can occur in the stromal and epithelial compartments of primary invasive breast carcinomas. Here, we demonstrate high frequencies of somatic mutations in TP53 (encoding tumor protein p53) and PTEN (encoding phosphate and tensin homolog) in breast neoplastic epithelium and stroma. Mutations in TP53 and PTEN are mutually exclusive in either compartment. In contrast, mutations in WFDC1 (16q24, encoding WAP four-disulfide core domain 1) occur with low frequency in the stroma.

Base Sequence↗
PubMed2002

APC-dependent suppression of colon carcinogenesis by PPARgamma.

Activation of PPARgamma by synthetic ligands, such as thiazolidinediones, stimulates adipogenesis and improves insulin sensitivity. Although thiazolidinediones represent a major therapy for type 2 diabetes, conflicting studies showing that these agents can increase or decrease colonic tumors in mice have raised concerns about the role of PPARgamma in colon cancer. To analyze critically the role of this receptor, we have used mice heterozygous for Ppargamma with both chemical and genetic models of this malignancy. Heterozygous loss of PPARgamma causes an increase in beta-catenin levels and a greater incidence of colon cancer when animals are treated with azoxymethane. However, mice with preexisting damage to Apc, a regulator of beta-catenin, develop tumors in a manner insensitive to the status of PPARgamma. These data show that PPARgamma can suppress beta-catenin levels and colon carcinogenesis but only before damage to the APC/beta-catenin pathway. This finding suggests a potentially important use for PPARgamma ligands as chemopreventative agents in colon cancer.

Animals↗
PubMed2002

The pressure rises: update on the genetics of phaeochromocytoma.

Phaeochromocytomas are neoplasias of neural crest origin arising from the adrenal medulla. Extra-adrenal phaeochromocytomas occur and may be referred to as paragangliomas, although this term is also used to describe vascular head and neck tumours, which most commonly develop at the carotid bifurcation. Historically, genetic factors have been implicated in up to 10% of phaeochromocytoma cases, but recent data suggest that germline mutations may be detected in approximately 25% of unselected cases. The most frequent causes of phaeochromocytoma susceptibility are von Hippel-Lindau disease (VHL), multiple endocrine neoplasia type 2 (MEN 2), the newly delineated phaeochromocytoma-paraganglioma syndrome and, less commonly, neurofibromatosis type 1. Germline mutations in three of the succinate dehydrogenase (SDH, mitochondrial complex II) subunits (SDHD, SDHB and SDHC) cause susceptibility to head and neck paragangliomas, and may be found in approximately 20% of unselected patients. In addition, germline SDHD and SDHB mutations may cause phaeochromocytoma susceptibility with or without associated head and neck paragangliomas. Recent studies suggest that germline SDHD and SDHB mutations are an important cause of familial and isolated phaeochromocytoma. The mechanism by which SDH subunit mutations predispose to phaeochromocytomas has not been defined in detail, but dysregulation of hypoxia-responsive genes and impairment of mitochondria-mediated apoptosis have both been suggested.

Adrenal Gland Neoplasms↗
PubMed2002

PTEN blocks insulin-mediated ETS-2 phosphorylation through MAP kinase, independently of the phosphoinositide 3-kinase pathway.

The tumor suppressor PTEN possesses lipid and protein phosphatase activities. It has been well established that the lipid phosphatase activity is essential for its tumor-suppressive function via the phosphoinositide 3-kinase (PI3K) and Akt pathways. The precise role of the protein phosphatase activity is still unclear. In the current study, we demonstrate that overexpression of wild-type PTEN in the MCF-7 breast cancer line results in phosphatase activity-dependent decreases in the phosphorylation of ETS-2, which is a transcription factor whose DNA-binding ability is controlled by phosphorylation. Exposure of MCF-7 cells to insulin, insulin-like growth factor 1 (IGF-1) or epidermal growth factor (EGF) can lead to the phosphorylation of ETS-2, Akt and ERK1/2. The MEK inhibitor PD590089 abrogates insulin-stimulated phosphorylation of ETS-2. In contrast, the PI3K inhibitor LY492002 has no effect on insulin-stimulated phosphorylation of ETS-2, despite the fact that it diminishes insulin-stimulated phosphorylation of Akt. Interestingly, overexpression of PTEN in MCF-7 leads to blockade of insulin-stimulated, but not EGF-stimulated, phosphorylation of ERK, accompanied by dramatic decreases in ETS-2 phosphorylation. We further show that the relationship of PTEN and ETS-2 has functional significance by demonstrating that PTEN abrogates activation of the uPA Ras-responsive enhancer, a target of ETS-2 action, in a phosphatase-dependent manner, irrespective of the presence or absence of insulin. Our observations, therefore, suggest that PTEN blocks insulin-stimulated ETS-2 phosphorylation through inhibition of the ERK members of the MAP kinase family independently of PI3K, and that the PTEN effect on the phosphorylation status of ETS-2 may be mediated through PTEN's protein phosphatase activity.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Germ-line mutations in nonsyndromic pheochromocytoma.

BACKGROUND: The group of susceptibility genes for pheochromocytoma that included the proto-oncogene RET (associated with multiple endocrine neoplasia type 2 [MEN-2]) and the tumor-suppressor gene VHL (associated with von Hippel-Lindau disease) now also encompasses the newly identified genes for succinate dehydrogenase subunit D (SDHD) and succinate dehydrogenase subunit B (SDHB), which predispose carriers to pheochromocytomas and glomus tumors. We used molecular tools to classify a large cohort of patients with pheochromocytoma with respect to the presence or absence of mutations of one of these four genes and to investigate the relevance of genetic analyses to clinical practice. METHODS: Peripheral blood from unrelated, consenting registry patients with pheochromocytoma was tested for mutations of RET, VHL, SDHD, and SDHB. Clinical data at first presentation and follow-up were evaluated. RESULTS: Among 271 patients who presented with nonsyndromic pheochromocytoma and without a family history of the disease, 66 (24 percent) were found to have mutations (mean age, 25 years; 32 men and 34 women). Of these 66, 30 had mutations of VHL, 13 of RET, 11 of SDHD, and 12 of SDHB. Younger age, multifocal tumors, and extraadrenal tumors were significantly associated with the presence of a mutation. However, among the 66 patients who were positive for mutations, only 21 had multifocal pheochromocytoma. Twenty-three (35 percent) presented after the age of 30 years, and 17 (8 percent) after the age of 40. Sixty-one (92 percent) of the patients with mutations were identified solely by molecular testing of VHL, RET, SDHD, and SDHB; these patients had no associated signs and symptoms at presentation. CONCLUSIONS: Almost one fourth of patients with apparently sporadic pheochromocytoma may be carriers of mutations; routine analysis for mutations of RET, VHL, SDHD, and SDHB is indicated to identify pheochromocytoma-associated syndromes that would otherwise be missed.

Adolescent↗
PubMed2002

Nuclear PTEN expression and clinicopathologic features in a population-based series of primary cutaneous melanoma.

Germline mutations of the PTEN tumor-suppressor gene, on 10q23, cause Cowden syndrome, an inherited hamartoma syndrome with a high risk of breast, thyroid and endometrial carcinomas and, some suggest, melanoma. To date, most studies which strongly implicate PTEN in the etiology of sporadic melanomas have depended on cell lines, short-term tumor cultures and noncultured metastatic melanomas. The only study which reports PTEN protein expression in melanoma focuses on cytoplasmic expression, mainly in metastatic samples. To determine how PTEN contributes to the etiology or the progression of primary cutaneous melanoma, we examined cytoplasmic and nuclear PTEN expression against clinical and pathologic features in a population-based sample of 150 individuals with incident primary cutaneous melanoma. Among 92 evaluable samples, 30 had no or decreased cytoplasmic PTEN protein expression and the remaining 62 had normal PTEN expression. In contrast, 84 tumors had no or decreased nuclear expression and 8 had normal nuclear PTEN expression. None of the clinical features studied, such as Clark's level and Breslow thickness or sun exposure, were associated with cytoplasmic PTEN expressional levels. An association with loss of nuclear PTEN expression was indicated for anatomical site (p = 0.06) and mitotic index (p = 0.02). There was also an association for melanomas to either not express nuclear PTEN or to express p53 alone, rather than both simultaneously (p = 0.02). In contrast with metastatic melanoma, where we have shown previously that almost two-thirds of tumors have some PTEN inactivation, only one-third of primary melanomas had PTEN silencing. This suggests that PTEN inactivation is a late event likely related to melanoma progression rather than initiation. Taken together with our previous observations in thyroid and islet cell tumors, our data suggest that nuclear-cytoplasmic partitioning of PTEN might also play a role in melanoma progression.

Aged↗
PubMed2002

Prevalence of germline mutations of MLH1 and MSH2 in hereditary nonpolyposis colorectal cancer families from Spain.

HNPCC is an autosomal dominantly inherited cancer-susceptibility syndrome that confers an increased risk for colorectal cancer and endometrial cancer at a young age. It also entails an increased risk of a variety of other tumors, such as ovarian, gastric, uroepithelial and biliary tract cancers. The underlying pathogenic mutation lies in 1 of the 5 known DNA MMR genes (MSH2, MLH1, PMS1, PMS2 and MSH6). We screened a total of 140 individuals from 56 Spanish families with suspected HNPCC for mutations in the DNA mismatch repair genes MLH1 and MSH2, using DGGE and direct DNA sequencing. Families were selected on the basis of a history of HNPCC-related tumors or the occurrence of other associated tumors in members besides the index case affected with colorectal cancer. We detected 14 definite pathogenic germline mutations, 9 in MLH1 and 5 in MSH2 in 13 unrelated families selected by the Amsterdam criteria and Bethesda guidelines (1 family carries 2 mutations) and 3 missense mutations in 3 unrelated families selected by the Amsterdam criteria. Among the 17 germline mutations noted in the Spanish cohort, 10 are novel, 7 in MLH1 and 3 in MSH2, perhaps demonstrating different mutational spectra in the Spanish population, where no founder mutation has been identified. Based on our results, we suggest that in the Spanish population not only HNPCC families fulfilling the Amsterdam criteria but also those following Bethesda guidelines should undergo genetic testing for MSH2 and MLH1 mutations.

Adaptor Proteins, Signal Transducing↗