A comprehensive molecular study on Coffin-Siris and Nicolaides-Baraitser syndromes identifies a broad molecular and clinical spectrum converging on altered chromatin remodeling.

Chromatin remodeling complexes are known to modify chemical marks on histones or to induce conformational changes in the chromatin in order to regulate transcription. De novo dominant mutations in different members of the SWI/SNF chromatin remodeling complex have recently been described in individuals with Coffin-Siris (CSS) and Nicolaides-Baraitser (NCBRS) syndromes. Using a combination of whole-exome sequencing, NGS-based sequencing of 23 SWI/SNF complex genes, and molecular karyotyping in 46 previously undescribed individuals with CSS and NCBRS, we identified a de novo 1-bp deletion (c.677delG, p.Gly226Glufs*53) and a de novo missense mutation (c.914G>T, p.Cys305Phe) in PHF6 in two individuals diagnosed with CSS. PHF6 interacts with the nucleosome remodeling and deacetylation (NuRD) complex implicating dysfunction of a second chromatin remodeling complex in the pathogenesis of CSS-like phenotypes. Altogether, we identified mutations in 60% of the studied individuals (28/46), located in the genes ARID1A, ARID1B, SMARCB1, SMARCE1, SMARCA2, and PHF6. We show that mutations in ARID1B are the main cause of CSS, accounting for 76% of identified mutations. ARID1B and SMARCB1 mutations were also found in individuals with the initial diagnosis of NCBRS. These individuals apparently belong to a small subset who display an intermediate CSS/NCBRS phenotype. Our proposed genotype-phenotype correlations are important for molecular screening strategies.

A novel inverted 17p13.3 microduplication disrupting PAFAH1B1 (LIS1) in a girl with syndromic lissencephaly.

We describe a female patient with mild lissencephaly (pachygyria), severe intellectual disability, and facial dysmorphisms with an inverted 1.4 Mb microduplication of chromosome 17p13.3. The 17p13.3 microduplication syndrome is associated with mild intellectual disabiltiy and contains, among others, the PAFAH1B1 (LIS1) gene, whereas microdeletions of the same segment cause Miller-Dieker syndrome (MDS) with severe to profound retardation. The duplication identified in our patient encompasses 29 genes, including CRK and YWHAE. The proximal breakpoint of the duplication is located in the first intron of the PAFAH1B1 gene. Analysis of total RNA showed that only one PAFAH1B1 allele is expressed. Therefore, this patient has a unique alteration: a duplication including YWHAE and CRK and haploinsufficiency of PAFAH1B1. Overexpression of YWHAE is associated with macrosomia, mild developmental delay, autism and facial dysmorphisms, and deletion of PAFAH1B1 alone leads to isolated lissencephaly (ILS). The patient described here shares features with MDS, but she is affected to a lesser degree. Her facial features are similar to MDS, and she has manifestations seen in other cases with YWHAE duplication.

Wide clinical variability in conditions with coarse facial features and hypertrichosis caused by mutations in ABCC9.

We present two previously unreported and unrelated female patients, one with the tentative diagnosis of acromegaloid facial appearance (AFA), the other with the tentative diagnosis of hypertrichosis with acromegaloid facial appearance (HAFF) with or without gingival hyperplasia. Main clinical features of HAFF were generalized hypertrichosis terminalis and coarse facial features. In both patients, pregnancy was complicated by polyhydramnios, and both had hyperbilirubinemia and persistent fetal circulation. Development was normal in one patient and slightly delayed in the other. At 13 years, both had round faces with full cheeks, thick scalp hair and eyebrows, a low frontal hairline, hirsutism, hyperextensible joints and deep palmar creases. One of them additionally showed gingival hypertrophy and epicanthus, the other one was macrocephalic at birth and at the age of 13 years and suffered from repeated swelling of the soft tissue. Array analysis excluded a 17q24.2-q24.3 microdeletion, which has been reported in patients with hypertrichosis terminalis with or without gingival hyperplasia. Sequencing of the mutational hotspots of the ABCC9 gene revealed two different de novo missense mutations in the two patients. Recently, identical mutations have been found recurrently in patients with Cantú syndrome. Therefore, we propose that ABCC9 mutations lead to a spectrum of phenotypes formerly known as Cantú syndrome, HAFF and AFA, which may not be clearly distinguishable by clinical criteria, and that all patients with clinical signs belonging to this spectrum should be revisited and offered ABCC9 mutation analysis.

Risks of less common cancers in proven mutation carriers with lynch syndrome.

PURPOSE: Patients with Lynch syndrome are at high risk for colon and endometrial cancer, but also at an elevated risk for other less common cancers. The purpose of this retrospective cohort study was to provide risk estimates for these less common cancers in proven carriers of pathogenic mutations in the mismatch repair (MMR) genes MLH1, MSH2, and MSH6. PATIENTS AND METHODS: Data were pooled from the German and Dutch national Lynch syndrome registries. Seven different cancer types were analyzed: stomach, small bowel, urinary bladder, other urothelial, breast, ovarian, and prostate cancer. Age-, sex- and MMR gene-specific cumulative risks (CRs) were calculated using the Kaplan-Meier method. Sex-specific incidence rates were compared with general population incidence rates by calculating standardized incidence ratios (SIRs). Multivariate Cox regression analysis was used to estimate the impact of sex and mutated gene on cancer risk. RESULTS: The cohort comprised 2,118 MMR gene mutation carriers (MLH1, n = 806; MSH2, n = 1,004; MSH6, n = 308). All cancers were significantly more frequent than in the general population. The highest risks were found for male small bowel cancer (SIR, 251; 95% CI, 177 to 346; CR at 70 years, 12.0; 95% CI, 5.7 to 18.2). Breast cancer showed an SIR of 1.9 (95% CI, 1.4 to 2.4) and a CR of 14.4 (95% CI, 9.5 to 19.3). MSH2 mutation carriers had a considerably higher risk of developing urothelial cancer than MLH1 or MSH6 carriers. CONCLUSION: The sex- and gene-specific differences of less common cancer risks should be taken into account in cancer surveillance and prevention programs for patients with Lynch syndrome.

Double heterozygosity for mutations in BRCA1 and BRCA2 in German breast cancer patients: implications on test strategies and clinical management.

Double heterozygosity for disease-causing BRCA1 and BRCA2 mutations is a very rare condition in most populations. Here we describe genetic and clinical data of eight female double heterozygotes (DH) for BRCA1 and BRCA2 mutations found in a cohort of 8162 German breast/ovarian cancer families and compare it with the data of their single heterozygous relatives and of the index patients of the German Consortium for Hereditary Breast and Ovarian Cancer. Furthermore, we analyze the phenotypic features of these patients with respect to age at onset of first cancer, first breast/ovarian cancer and the number of disease manifestations and compare them to that of published Caucasian female DHs and their single heterozygous female relatives. German DHs were not significantly younger at diagnosis of first breast cancer than the single heterozygous index patients of the German Consortium. However, if the data of our study were pooled with that of the literature, DHs were substantially younger at onset of first cancer (mean age 40.4 years, 95 % CI = 36.6-44.1) than their single heterozygous female relatives (mean age 51.9 years, 95 % CI = 46.8-57.0). The two groups also differed concerning the onset of first breast cancer (mean age 40.6 years, 95 % CI = 36.6-44.5 vs. 52.6, 95 % CI = 47.5-57.6). In addition, DHs had a more severe disease than their female relatives carrying a single BRCA mutation (1.4 vs. 0.6 manifestations per person). In contrast to Ashkenazi Jewish females, Caucasian DH females might develop breast cancer at an earlier age and have a more severe disease than single heterozygous BRCA mutation carriers. Therefore, DHs may benefit from more intensive surveillance programs/follow-up care and prophylactic surgery.

New mutations in the ATM gene and clinical data of 25 AT patients.

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar degeneration, immunodeficiency, oculocutaneous telangiectasias, chromosomal instability, radiosensitivity, and cancer predisposition. The gene mutated in the patients, ATM, encodes a member of the phosphatidylinositol 3-kinase family proteins. The ATM protein has a key role in the cellular response to DNA damage. Truncating and splice site mutations in ATM have been found in most patients with the classical AT phenotype. Here we report of our extensive ATM mutation screening on 25 AT patients from 19 families of different ethnic origin. Previously unknown mutations were identified in six patients including a new homozygous missense mutation, c.8110T>C (p.Cys2704Arg), in a severely affected patient. Comprehensive clinical data are presented for all patients described here along with data on ATM function generated by analysis of cell lines established from a subset of the patients.

Polymorphisms in CTNNBL1 in relation to colorectal cancer with evolutionary implications.

Colorectal cancer (CRC) is a complex disease related to environmental and genetic risk factors. Several studies have shown that susceptibility to complex diseases can be mediated by ancestral alleles. Using RNAi screening, CTNNBL1 was identified as a putative regulator of the Wnt signaling pathway, which plays a key role in colorectal carcinogenesis. Recently, single nucleotide polymorphisms (SNPs) in CTNNBL1 have been associated with obesity, a known risk factor for CRC. We investigated whether genetic variation in CTNNBL1 affects susceptibility to CRC and tested for signals of recent selection. We applied a tagging SNP approach that cover all known common variation in CTNNBL1 (allele frequency >5%; r(2)>0.8). A case-control study was carried out using two well-characterized study populations: a hospital-based Czech population composed of 751 sporadic cases and 755 controls and a family/early onset-based German population (697 cases and 644 controls). Genotyping was performed using allele specific PCR based TaqMan® assays (Applied Biosystems, Weiterstadt, Germany). In the Czech cohort, containing sporadic cases, the ancestral alleles of three SNPs showed evidence of association with CRC: rs2344481 (OR 1.44, 95%CI 1.06-1.95, dominant model), rs2281148 (OR 0.59, 95%CI 0.36-0.96, dominant model) and rs2235460 (OR 1.38, 95%CI 1.01-1.89, AA vs. GG). The associations were less prominent in the family/early onset-based German cohort. Data derived from several databases and statistical tests consistently pointed to a likely shaping of CTNNBL1 by positive selection. Further studies are needed to identify the actual function of CTNNBL1 and to validate the association results in other populations.

Missense variants in hMLH1 identified in patients from the German HNPCC consortium and functional studies.

Missense mutations of the DNA mismatch repair gene MLH1 are found in a significant fraction of patients with Lynch syndrome (hereditary nonpolyposis colorectal cancer, HNPCC) and their pathogenicity often remains unclear. We report here all 88 MLH1 missense variants identified in families from the German HNPCC consortium with clinical details of these patients/families. We investigated 23 MLH1 missense variants by two functional in vivo assays in yeast; seven map to the ATPase and 16 to the protein interaction domain. In the yeast-2-hybrid (Y2H) assay three variants in the ATPase and twelve variants in the interaction domain showed no or a reduced interaction with PMS2; seven showed a normal and one a significantly higher interaction. Using the Lys2A (14) reporter system to study the dominant negative mutator effect (DNE), 16 variants showed no or a low mutator effect, suggesting that these are nonfunctional, three were intermediate and four wild type in this assay. The DNE and Y2H results were concordant for all variants in the interaction domain, whereas slightly divergent results were obtained for variants in the ATPase domain. Analysis of the stability of the missense proteins in yeast and human embryonic kidney cells (293T) revealed a very low expression for seven of the variants in yeast and for nine in human cells. In total 15 variants were classified as deleterious, five were classified as variants of unclassified significance (VUS) and three were basically normal in the functional assays, P603R, K618R, Q689R, suggesting that these are neutral.

Genome-wide association study for colorectal cancer identifies risk polymorphisms in German familial cases and implicates MAPK signalling pathways in disease susceptibility.

Genetic susceptibility accounts for approximately 35% of all colorectal cancer (CRC). Ten common low-risk variants contributing to CRC risk have been identified through genome-wide association studies (GWASs). In our GWAS, 610 664 genotyped single-nucleotide polymorphisms (SNPs) passed the quality control filtering in 371 German familial CRC patients and 1263 controls, and replication studies were conducted in four additional case-control sets (4915 cases and 5607 controls). Known risk loci at 8q24.21 and 11q23 were confirmed, and a previously unreported association, rs12701937, located between the genes GLI3 (GLI family zinc finger 3) and INHBA (inhibin, beta A) [P = 1.1 x 10(-3), odds ratio (OR) 1.14, 95% confidence interval (CI) 1.05-1.23, dominant model in the combined cohort], was identified. The association was stronger in familial cases compared with unselected cases (P = 2.0 x 10(-4), OR 1.36, 95% CI 1.16-1.60, dominant model). Two other unreported SNPs, rs6038071, 40 kb upstream of CSNK2A1 (casein kinase 2, alpha 1 polypeptide) and an intronic marker in MYO3A (myosin IIIA), rs11014993, associated with CRC only in the familial CRC cases (P = 2.5 x 10(-3), recessive model, and P = 2.7 x 10(-4), dominant model). Three software tools successfully pointed to the overrepresentation of genes related to the mitogen-activated protein kinase (MAPK) signalling pathways among the 1340 most strongly associated markers from the GWAS (allelic P value < 10(-3)). The risk of CRC increased significantly with an increasing number of risk alleles in seven genes involved in MAPK signalling events (P(trend) = 2.2 x 10(-16), OR(per allele) = 1.34, 95% CI 1.11-1.61).

Truncating mutations in Peutz-Jeghers syndrome are associated with more polyps, surgical interventions and cancers.

BACKGROUND AND GOALS: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant polyposis syndrome caused by STK11 germline mutations. PJS is associated with an increased risk of cancer. In our cohort, clinical and phenotypic parameters were correlated with genotypic findings and patients were prospectively followed by surveillance. STUDY: Thirty-one patients treated between 2000 and 2006, were evaluated. STK11 genotyping was performed and phenotypes of patients with truncating (TM) and nontruncating mutations (NTM) were compared. RESULTS: Median age at first symptoms was 11 years and complications occurred before the age of ten in 42% of patients. STK11 mutations were detected in 16 of 22 families (12 TM; four NTM). Patients with TM had more surgical gastrointestinal (GI) interventions (p = 0.021), and female patients in the TM group had an increased risk of undergoing gynecological surgery (p = 0.016). Also, there was a trend towards a higher polyp count (p = 0.11) and earlier age at first polypectomy (p = 0.13) in the TM group. Ten carcinomas were detected in six patients resulting in a cancer risk of 65% up to the age of 65 years. Patients with TM tended to develop more cancers (p = 0.10). Importantly, our surveillance strategy used detected 50% of cancers (n = 5) at an early potentially curable stage. CONCLUSIONS: Our study shows that almost half of PJ patients have complications early in life independent of mutational status. Patients with TM require more surgical GI interventions and tend to develop more polyps and cancers. Furthermore, close surveillance detects early stage cancers in patients. We propose that surveillance should be started as early as 8 years in all patients to avoid complications. Moreover, patients with TM may benefit from surveillance at shorter intervals.

Efficacy of annual colonoscopic surveillance in individuals with hereditary nonpolyposis colorectal cancer.

BACKGROUND & AIMS: Individuals with hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome) have a high risk for developing colorectal cancer (CRC). We evaluated the efficacy of annual surveillance colonoscopies to detect adenomas and CRCs. METHODS: In a prospective, multicenter cohort study, 1126 individuals underwent 3474 colonoscopies. We considered individuals from 3 groups of HNPCC families: those with a pathogenic germline mutation in a mismatch repair gene (MUT group), those without a mutation but with microsatellite instability (MSI group), and those who fulfilled the Amsterdam criteria without microsatellite instability (MSS group). RESULTS: Compliance to annual intervals was good, with 81% of colonoscopies completed within 15 months. Ninety-nine CRC events were observed in 90 patients. Seventeen CRCs (17%) were detected through symptoms (8 before baseline colonoscopy, 8 at intervals >15 months to the preceding colonoscopy, and 1 interval cancer). Only 2 of 43 CRCs detected by follow-up colonoscopy were regionally advanced. Tumor stages were significantly lower among CRCs detected by follow-up colonoscopies compared with CRCs detected by symptoms (P = .01). Cumulative CRC risk at the age of 60 years was similar in the MUT and MSI groups (23.0% combined; 95% confidence interval [CI], 14.8%-31.2%) but considerably lower in the MSS group (1.8%; 95% CI, 0.0%-5.1%). Adenomas at baseline colonoscopy predicted an earlier occurrence of subsequent adenoma (hazard ratio, 2.6; 95% CI, 1.7-4.0) and CRC (hazard ratio, 3.9; 95% CI, 1.7-8.5), providing information about interindividual heterogeneity of adenomas and kinetics of CRC formation. CONCLUSIONS: Annual colonoscopic surveillance is recommended for individuals with HNPCC. Less intense surveillance might be appropriate for MSS families.

Comparative in silico analyses and experimental validation of novel splice site and missense mutations in the genes MLH1 and MSH2.

Hereditary non-polyposis colorectal cancer, an autosomal dominant predisposition to colorectal cancer and other malignancies, is caused by inactivating mutations of DNA mismatch repair genes, mainly MLH1 and MSH2. Missense mutations affect protein structure or function, but may also cause aberrant splicing, if located within splice sites (ss) or cis-acting sequences of splicing regulatory proteins, i.e., exonic splicing enhancers or exonic splicing silencers. Despite significant progress of ss scoring algorithms, the prediction for the impact of mutations on splicing is still unsatisfactory. For this study, we assessed ten ss and nine missense mutations outside ss in MLH1 and MSH2, including eleven newly identified mutations, and experimentally analyzed their effect at the RNA level. We additionally tested and compared the reliability of several web-based programs for the prediction of splicing outcome for these mutations.

Multiple giant cell lesions in patients with Noonan syndrome and cardio-facio-cutaneous syndrome.

Noonan syndrome (NS) and cardio-facio-cutaneous syndrome (CFCS) are related developmental disorders caused by mutations in genes encoding various components of the RAS-MAPK signaling cascade. NS is associated with mutations in the genes PTPN11, SOS1, RAF1, or KRAS, whereas CFCS can be caused by mutations in BRAF, MEK1, MEK2, or KRAS. The NS phenotype is rarely accompanied by multiple giant cell lesions (MGCL) of the jaw (Noonan-like/MGCL syndrome (NL/MGCLS)). PTPN11 mutations are the only genetic abnormalities reported so far in some patients with NL/MGCLS and in one individual with LEOPARD syndrome and MGCL. In a cohort of 75 NS patients previously tested negative for mutations in PTPN11 and KRAS, we detected SOS1 mutations in 11 individuals, four of whom had MGCL. To explore further the relevance of aberrant RAS-MAPK signaling in syndromic MGCL, we analyzed the established genes causing CFCS in three subjects with MGCL associated with a phenotype fitting CFCS. Mutations in BRAF or MEK1 were identified in these patients. All mutations detected in these seven patients with syndromic MGCL had previously been described in NS or CFCS without apparent MGCL. This study demonstrates that MGCL may occur in NS and CFCS with various underlying genetic alterations and no obvious genotype-phenotype correlation. This suggests that dysregulation of the RAS-MAPK pathway represents the common and basic molecular event predisposing to giant cell lesion formation in patients with NS and CFCS rather than specific mutation effects.

Waardenburg syndrome type I with heterochromia iridis and circumscribed hypopigmentation of the skin.

We report a 3-year-old girl with autosomal dominant inherited Waardenburg syndrome type I showing circumscribed hypopigmentation of the skin, heterochromia iridis, sensorineural deafness, and dental aberrations. Clinical diagnosis was confirmed by the identification of an underlying missense mutation (C811T) in the PAX3 gene. Early diagnosis of Waardenburg syndrome among children with pigment anomalies enables a successful interdisciplinary medical care.

Ten recently identified associations between nsSNPs and colorectal cancer could not be replicated in German families.

Ten non-synonymous single nucleotide polymorphisms (nsSNPs), which were recently associated with colorectal cancer risk in a comprehensive, array based study (AKAP9 M463I, DKK3 G335R, AMPD1 Q12X, LIPC L356F, PSMB9 V32I, THBS1 N700S, CA6 S90G, ASCC3 C1995S, DHX36 S416C and CPA4 G303C) were re-evaluated in the present study based on 626 German familial non-HNPCC colorectal cancer patients and 736 healthy controls. No associations of any of the 10 nsSNPs with colorectal cancer could be replicated. The combined analyses indicated that further research based on additional independent samples is required.

Deciphering the genetics of hereditary non-syndromic colorectal cancer.

Previously we have localized to chromosome 3q21-q24, a predisposition locus for colorectal cancer (CRC), through a genome-wide linkage screen (GWLS) of 69 families without familial adenomatous polyposis or hereditary non-polyposis CRC. To further investigate Mendelian susceptibility to CRC, we extended our screen to include a further GWLS of an additional 34 CRC families. We also searched for a disease gene at 3q21-q24 by linkage disequilibrium mapping in 620 familial CRC cases and 960 controls by genotyping 1676 tagging SNPs and sequencing 30 candidate genes from the region. Linkage analysis was conducted using the Affymetrix 10K SNP array. Data from both GWLSs were pooled and multipoint linkage statistics computed. The maximum NPL score (3.01; P=0.0013) across all families was at 3q22, maximal evidence for linkage coming from families segregating rectal CRC. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under a dominant model (HLOD=2.79; P=0.00034), with an estimated 43% of families linked. In the case-control analysis, the strongest association was obtained at rs698675 (P=0.0029), but this was not significant after adjusting for multiple testing. Analysis of candidate gene mapping to the region of maximal linkage on 3q22 failed to identify a causal mutation. There was no evidence for linkage to the previously reported 9q CRC locus (NPL=0.95, P=0.23; HLOD(dominant)=0.40, HLOD(recessive)=0.20). Our findings are consistent with the hypothesis that variation at 3q22 contributes to the risk of CRC, but this is unlikely to be mediated through a restricted set of alleles.

MLPA screening in the BRCA1 gene from 1,506 German hereditary breast cancer cases: novel deletions, frequent involvement of exon 17, and occurrence in single early-onset cases.

We present a comprehensive analysis of 1,506 German families for large genomic rearrangements (LGRs) in the BRCA1 gene and of 450 families in the BRCA2 gene by the multiplex ligation-dependent probe amplification (MLPA) technique. A total of 32 pathogenic rearrangements in the BRCA1 gene were found, accounting for 1.6% of all mutations, but for 9.6% of all BRCA1 mutations identified in a total of 1,996 families, including 490 with small pathogenic BRCA1/2 mutations. Considering only high risk groups for hereditary breast/ovarian cancer, the prevalence of rearrangements is 2.1%. Interestingly, deletions involving exon 17 of the BRCA1 gene seem to be most frequent in Germany. Apart from recurrent aberrations like del ex17, dupl ex13, and del ex22, accounting for more than 50% of all BRCA1 LGRs, we could fully characterize 11 novel deletions. Moreover, one novel deletion involving exons 1-7 and one deletion affecting the entire BRCA1 gene were identified. All rearrangements were detected in families with: 1) at least two breast cancer cases prior to the age of 51 years; 2) breast and ovarian cancer cases; 3) ovarian cancer only families with at least two ovarian cancer cases; or 4) a single breast cancer case prior to the age of 36 years, while no mutations were detected in breast cancer only families with no or only one breast cancer case prior to the age of 51 years. Analysis for gross rearrangements in 412 high-risk individuals, revealed no event in the BRCA2 gene and only two known CHEK2 mutations. However, in an additional 38 high-risk families with cooccurrence of female breast/ovarian and male breast cancer, one rearrangement in the BRCA2 gene was found. In summary, we advise restricting BRCA1 MLPA screening to those subgroups that revealed LGRs and recommend BRCA2 MLPA screening only for families presenting with cooccurrence of female and male breast cancer.

Congenital central hypoventilation syndrome with hyperinsulinism in a preterm infant.

Congenital central hypoventilation syndrome (CCHS), a rare disorder typically presenting in the newborn period, results in over 90% of cases from PHOX2B polyalanine repeat mutations. It is characterized by alveolar hypoventilation, symptoms of autonomic nervous system dysregulation, and in a subset of cases Hirschsprung's disease and, later, tumors of neural crest origin. We describe a preterm infant with severe phenotype of CCHS and hyperinsulinism. A novel de novo heterozygote missence mutation (Gly68Cys) in the PHOX2B gene could be identified. Based on the observation of three patients presenting with the combination of congenital hyperinsulinism and CCHS, hyperinsulinism might represent an additional clinical feature of CCHS.

Mutations in the pericentrin (PCNT) gene cause primordial dwarfism.

Fundamental processes influencing human growth can be revealed by studying extreme short stature. Using genetic linkage analysis, we find that biallelic loss-of-function mutations in the centrosomal pericentrin (PCNT) gene on chromosome 21q22.3 cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II) in 25 patients. Adults with this rare inherited condition have an average height of 100 centimeters and a brain size comparable to that of a 3-month-old baby, but are of near-normal intelligence. Absence of PCNT results in disorganized mitotic spindles and missegregation of chromosomes. Mutations in related genes are known to cause primary microcephaly (MCPH1, CDK5RAP2, ASPM, and CENPJ).

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.