Elisabeth Mangold

Key susceptibility locus for nonsyndromic cleft lip with or without cleft palate on chromosome 8q24.

We conducted a genome-wide association study involving 224 cases and 383 controls of Central European origin to identify susceptibility loci for nonsyndromic cleft lip with or without cleft palate (NSCL/P). A 640-kb region at chromosome 8q24.21 was found to contain multiple markers with highly significant evidence for association with the cleft phenotype, including three markers that reached genome-wide significance. The 640-kb cleft-associated region was saturated with 146 SNP markers and then analyzed in our entire NSCL/P sample of 462 unrelated cases and 954 controls. In the entire sample, the most significant SNP (rs987525) had a P value of 3.34 × 10−24. The odds ratio was 2.57 (95% CI = 2.02–3.26) for the heterozygous genotype and 6.05 (95% CI = 3.88–9.43) for the homozygous genotype. The calculated population attributable risk for this marker is 0.41, suggesting that this study has identified a major susceptibility locus for NSCL/P.

Genome-wide association study identifies two susceptibility loci for nonsyndromic cleft lip with or without cleft palate

We conducted a genome-wide association study for nonsyndromic cleft lip with or without cleft palate (NSCL/P) in 401 affected individuals and 1,323 controls, with replication in an independent sample of 793 NSCL/P triads. We report two new loci associated with NSCL/P at 17q22 (rs227731, combined P = 1.07 × 10−8, relative risk in homozygotes = 1.84, 95% CI 1.34–2.53) and 10q25.3 (rs7078160, combined P = 1.92 × 10−8, relative risk in homozygotes = 2.17, 95% CI 1.32–3.56).

Can APC mutation analysis contribute to therapeutic decisions in familial adenomatous polyposis? Experience from 680 FAP families

BACKGROUND AND AIMS In familial adenomatous polyposis (FAP), correlations between site of mutation in the adenomatous polyposis coli (APC) gene and severity of colonic polyposis or extracolonic manifestations are well known. While mutation analysis is important for predictive diagnosis in persons at risk, its relevance for clinical management of individual patients is open to question. METHODS We examined 680 unrelated FAP families for germline mutations in theAPC gene. Clinical information was obtained from 1256 patients. RESULTS APC mutations were detected in 48% (327/680) of families. Age at diagnosis of FAP based on bowel symptoms and age at diagnosis of colorectal cancer in untreated patients were used as indicators of the severity of the natural course of the disease. A germline mutation was detected in 230 of 404 patients who were diagnosed after onset of bowel symptoms (rectal bleeding, abdominal pain, diarrhoea). When these patients were grouped according to the different sites of mutations, mean values for age at onset of disease differed significantly: patients carryingAPC mutations at codon 1309 showed a disease onset 10 years earlier (mean age 20 years) compared with patients with mutations between codons 168 and 1580 (except codon 1309) (mean age 30 years), whereas patients with mutations at the 5′ end of codon 168 or the 3′ end of codon 1580 were diagnosed at a mean age of 52 years. Within each group of patients however large phenotypic variation was observed, even among patients with identical germline mutations. A higher incidence of desmoids was found in patients with mutations between codons 1445 and 1580 compared with mutations at other sites, while no correlation between site of mutation and presence of duodenal adenomas was observed. CONCLUSIONS As age at manifestation and course of the disease may be rather variable, even in carriers of identical germline mutations, therapeutic decisions should be based on colonoscopic findings in individual patients rather than on the site of mutation. However, in patients with mutations within codons 1445–1580, it may be advisable to postpone elective colectomy because desmoids may arise through surgical intervention.

Lower Incidence of Colorectal Cancer and Later Age of Disease Onset in 27 Families With Pathogenic MSH6 Germline Mutations Compared With Families With MLH1 or MSH2 Mutations: The German Hereditary Nonpolyposis Colorectal Cancer Consortium

PURPOSE The aim of the study was the analysis of the involvement and phenotypic manifestations of MSH6 germline mutations in families suspected of hereditary nonpolyposis colorectal cancer (HNPCC). PATIENTS AND METHODS Patients were preselected among 706 families by microsatellite instability, immunohistochemistry, and/or exclusion of MLH1 or MSH2 mutations and were subjected to MSH6 mutation analysis. Clinical and molecular data of MSH6 mutation families were compared with data from families with MLH1 and MSH2 mutations. RESULTS We identified 27 families with 24 different pathogenic MSH6 germline mutations, representing 3.8% of the total of the families, and 14.7% of all families with DNA mismatch repair (MMR) gene mutations (n = 183). The median age of onset of colorectal cancer in putative mutation carriers was 10 years higher for MSH6 (54 years; 95% CI, 51 to 56) compared with MLH1 and MSH2 (44 years; 95% CI, 43 to 45; log-rank test, P = .0038). Relative to other malignant tumors, colorectal cancer was less frequent in MSH6 families compared with MLH1 and MSH2 families (Fishers exact test, P < .001). In contrast, the frequency of non-HNPCC-associated tumors was increased (Fishers exact test, P < .001). CONCLUSION Later age of disease onset and lower incidence of colorectal cancer may contribute to a lower proportion of identified MSH6 mutations in families suspected of HNPCC. However, in approximately half of these families, at least one patient developed colorectal or endometrial cancer in the fourth decade of life. Therefore, a surveillance program as stringent as that for families with MLH1 or MSH2 mutations is recommended.

MUTYH‐associated polyposis: 70 of 71 patients with biallelic mutations present with an attenuated or atypical phenotype

To determine the frequency, mutation spectrum and phenotype of the recently described autosomal recessive MUTYH‐associated polyposis (MAP), we performed a systematic search for MUTYH (MYH) mutations by sequencing the complete coding region of the gene in 329 unselected APC mutation‐negative index patients with the clinical diagnosis of familial adenomatous polyposis (FAP) or attenuated FAP (AFAP). Biallelic germline mutations in MUTYH were identified in 55 of the 329 unselected patients (17%) and in another 9 selected index cases. About one‐fifth (20%) of the 64 unrelated MAP patients harboured none of the 2 hot‐spot missense mutations Y165C and/or G382D. Including 7 affected relatives, almost all MAP patients presented with either an attenuated (80%) or with an atypical phenotype (18%). Fifty percentage of the MAP patients had colorectal cancer at diagnosis. Duodenal polyposis was found in 18%, thyroid and stomach cancer in 1 case, other extraintestinal manifestations associated with FAP were not observed. In 8 families, vertical segregation was suspected; in 2 of these families, biallelic mutations were identified in 2 generations. Monoallelic changes with predicted functional relevance were found in 0.9% of the 329 patients, which is in accordance with the carrier frequency in the general population. In conclusion, biallelic MUTYH mutations are the underlying genetic basis in a substantial fraction of patients with adenomatous polyposis. The phenotype of MAP is best characterised as attenuated or atypical, respectively. Colorectal surveillance starting at about 18 years of age is recommended for biallelic mutation carriers and siblings of MAP patients, who refuse predictive testing.

Genome-wide meta-analyses of nonsyndromic cleft lip with or without cleft palate identify six new risk loci

We have conducted the first meta-analyses for nonsyndromic cleft lip with or without cleft palate (NSCL/P) using data from the two largest genome-wide association studies published to date. We confirmed associations with all previously identified loci and identified six additional susceptibility regions (1p36, 2p21, 3p11.1, 8q21.3, 13q31.1 and 15q22). Analysis of phenotypic variability identified the first specific genetic risk factor for NSCLP (nonsyndromic cleft lip plus palate) (rs8001641; PNSCLP = 6.51 × 10−11; homozygote relative risk = 2.41, 95% confidence interval (CI) 1.84–3.16).

Juvenile polyposis: massive gastric polyposis is more common in MADH4 mutation carriers than in BMPR1A mutation carriers

Abstract. Juvenile polyposis syndrome (JPS) is an autosomal dominant predisposition to multiple juvenile polyps in the gastrointestinal tract. Germline mutations in the MADH4 or BMPR1A genes have been found to be causative of the disease in a subset of JPS patients. So far, no genotype-phenotype correlation has been reported. We examined 29 patients with the clinical diagnosis of JPS for germline mutations in the MADH4 or BMPR1A genes and identified MADH4 mutations in seven (24%) and BMPR1A mutations in five patients (17%). A remarkable prevalence of massive gastric polyposis was observed in patients with MADH4 mutations when compared with patients with BMPR1A mutations or without identified mutations. This is the first genotype-phenotype correlation observed in JPS.

Loss of DNA mismatch repair proteins in skin tumors from patients with Muir-Torre syndrome and MSH2 or MLH1 germline mutations: establishment of immunohistochemical analysis as a screening test.

Muir-Torre syndrome (MTS) is a rare autosomal-dominant disorder characterized by the predisposition to both sebaceous skin tumors (or multiple keratoacanthomas) and internal malignancies. A subtype of MTS is allelic to hereditary nonpolyposis colorectal cancer and is caused by germline mutations in the DNA mismatch repair genes MSH2 or MLH1. In these cases both internal and skin tumors show characteristic microsatellite instability (MSI). The aim of the present study was to determine whether immunohistochemical examination of MSH2 or MLH1 protein expression in MTS-associated skin tumors can be used as a diagnostic screening tool to identify patients with germline mutations in MSH2 or MLH1. In the present study 28 skin lesions from 17 patients (20 sebaceous gland tumors, 4 sebaceous hyperplasias, 3 keratoacanthomas, and 1 squamous cell carcinoma) were tested immunohistochemically with antibodies against MSH2 and MLH1. Eighteen of these tumors were from eight patients with known MSH2 germline mutations, two tumors were from a patient with a germline mutation in MLH1, and eight microsatellite stable sporadic skin tumors served as controls. One sample had to be excluded because of a lack of immunoreactivity. All eight microsatellite stable tumors expressed both DNA repair proteins. In 15 of the tumors from MSH2 germline mutation carriers, loss of MSH2 expression was observed, one tumor showed reduced MSH2 expression, and one tumor displayed positive immunoreactivity to MSH2. Both tumors of the MLH1 germline mutation carrier showed loss of the MLH1 protein. In conclusion, our findings demonstrate that immunohistochemical testing of MTS-related skin tumors is a reliable screening method with high predictive value for the diagnosis of the DNA mismatch repair-deficient MTS.

Genotype-Phenotype Comparison of German MLH1 and MSH2 Mutation Carriers Clinically Affected With Lynch Syndrome: A Report by the German HNPCC Consortium

PURPOSE Lynch syndrome is linked to germline mutations in mismatch repair genes. We analyzed the genotype-phenotype correlations in the largest cohort so far reported. PATIENTS AND METHODS Following standard algorithms, we identified 281 of 574 unrelated families with deleterious germline mutations in MLH1 (n = 124) or MSH2 (n = 157). A total of 988 patients with 1,381 cancers were included in this analysis. RESULTS We identified 181 and 259 individuals with proven or obligatory and 254 and 294 with assumed MLH1 and MSH2 mutations, respectively. Age at diagnosis was younger both in regard to first cancer (40 v 43 years; P < .009) and to first colorectal cancer (CRC; 41 v 44 years; P = .004) in MLH1 (n = 435) versus MSH2 (n = 553) mutation carriers. In both groups, rectal cancers were remarkably frequent, and the time span between first and second CRC was smaller if the first primary occurred left sided. Gastric cancer was the third most frequent malignancy occurring without a similarly affected relative in most cases. All prostate cancers occurred in MSH2 mutation carriers. CONCLUSION The proportion of rectal cancers and shorter time span to metachronous cancers indicates the need for a defined treatment strategy for primary rectal cancers in hereditary nonpolyposis colorectal cancer patients. Male MLH1 mutation carriers require earlier colonoscopy beginning at age 20 years. We propose regular gastric surveillance starting at age 35 years, regardless of the familial occurrence of this cancer. The association of prostate cancer with MSH2 mutations should be taken into consideration both for clinical and genetic counseling practice.

A genotype-phenotype correlation in HNPCC: strong predominance of msh2 mutations in 41 patients with Muir- Torre syndrome

Muir-Torre syndrome (MTS; MIM 158320) is an autosomal dominant predisposition to skin tumours and various internal malignancies. Clinical criteria for a diagnosis of MTS are the synchronous or metachronous occurrence of at least one sebaceous gland neoplasia and at least one internal neoplasm in a patient (regardless of the family history).1,2 The sebaceous gland neoplasias comprise adenomas, epitheliomas (sebaceomas), and carcinomas. In contrast, the frequent sebaceous gland hyperplasia is not indicative of MTS.2,3 According to Schwartz and Torre,2 the sebaceous neoplasias precede the internal neoplasias or are concurrent with them in 41% of MTS patients. As sebaceous gland neoplasias are rare, MTS should always be suspected when a sebaceous tumour has been diagnosed. Cystic sebaceous neoplasia is probably the most sensitive marker for this tumour predisposition syndrome.2,4–6 Colorectal cancer is by far the most common internal malignancy in MTS patients.7 The spectrum of internal malignancies in MTS is similar to the various tumour entities observed in hereditary non-polyposis colorectal cancer (HNPCC; MIM 114500). HNPCC is an autosomal dominant cancer predisposition syndrome characterised by early onset of colorectal cancer and other associated tumours.8,9 Several genes underlying HNPCC which are involved in DNA mismatch repair (MMR) have been identified within the last decade.10–13 Germline mutations in the DNA MMR genes were detected in a high proportion of MTS patients, demonstrating that MTS most often represents a phenotypic variant of HNPCC.14,15 Due to the underlying genetic mechanisms of tumourigenesis, tumours of these MTS patients exhibit high microsatellite instability (MSI-H), the characteristic feature of HNPCC tumours.16 Microsatellite analysis in tumour tissue of MTS patients therefore provides a useful tool to pre-select patients for mutation analysis in DNA MMR genes.3 Immunohistochemical testing for expression of the MSH2 and …