Histone H3.3 beyond cancer: Germline mutations in Histone 3 Family 3A and 3B cause a previously unidentified neurodegenerative disorder in 46 patients

Although somatic mutations in Histone 3.3 (H3.3) are well-studied drivers of oncogenesis, the role of germline mutations remains unreported. We analyze 46 patients bearing de novo germline mutations in histone 3 family 3A (H3F3A) or H3F3B with progressive neurologic dysfunction and congenital anomalies without malignancies. Molecular modeling of all 37 variants demonstrated clear disruptions in interactions with DNA, other histones, and histone chaperone proteins. Patient histone posttranslational modifications (PTMs) analysis revealed notably aberrant local PTM patterns distinct from the somatic lysine mutations that cause global PTM dysregulation. RNA sequencing on patient cells demonstrated up-regulated gene expression related to mitosis and cell division, and cellular assays confirmed an increased proliferative capacity. A zebrafish model showed craniofacial anomalies and a defect in Foxd3-derived glia. These data suggest that the mechanism of germline mutations are distinct from cancer-associated somatic histone mutations but may converge on control of cell proliferation.

DNA repair and cancer in colon and rectum: Novel players in genetic susceptibility

Interindividual differences in DNA repair systems may play a role in modulating the individual risk of developing colorectal cancer. To better ascertain the role of DNA repair gene polymorphisms on colon and rectal cancer risk individually, we evaluated 15,419 single nucleotide polymorphisms (SNPs) within 185 DNA repair genes using GWAS data from the Colon Cancer Family Registry (CCFR) and the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), which included 8,178 colon cancer, 2,936 rectum cancer cases and 14,659 controls. Rs1800734 (in MLH1 gene) was associated with colon cancer risk (p-value = 3.5 × 10-6 ) and rs2189517 (in RAD51B) with rectal cancer risk (p-value = 5.7 × 10-6 ). The results had statistical significance close to the Bonferroni corrected p-value of 5.8 × 10-6 . Ninety-four SNPs were significantly associated with colorectal cancer risk after Binomial Sequential Goodness of Fit (BSGoF) procedure and confirmed the relevance of DNA mismatch repair (MMR) and homologous recombination pathways for colon and rectum cancer, respectively. Defects in MMR genes are known to be crucial for familial form of colorectal cancer but our findings suggest that specific genetic variations in MLH1 are important also in the individual predisposition to sporadic colon cancer. Other SNPs associated with the risk of colon cancer (e.g., rs16906252 in MGMT) were found to affect mRNA expression levels in colon transverse and therefore working as possible cis-eQTL suggesting possible mechanisms of carcinogenesis.

Mendelian randomisation study of age at menarche and age at menopause and the risk of colorectal cancer

Background

Substantial evidence supports an association between use of menopausal hormone therapy and decreased colorectal cancer (CRC) risk, indicating a role of exogenous sex hormones in CRC development. However, findings on endogenous oestrogen exposure and CRC are inconsistent.

Methods

We used a Mendelian randomisation approach to test for a causal effect of age at menarche and age at menopause as surrogates for endogenous oestrogen exposure on CRC risk. Weighted genetic risk scores based on 358 single-nucleotide polymorphisms associated with age at menarche and 51 single-nucleotide polymorphisms associated with age at menopause were used to estimate the association with CRC risk using logistic regression in 12,944 women diagnosed with CRC and 10,741 women without CRC from three consortia. Sensitivity analyses were conducted to address pleiotropy and possible confounding by body mass index.

Results

Genetic risk scores for age at menarche (odds ratio per year 0.98, 95% confidence interval: 0.95–1.02) and age at menopause (odds ratio 0.98, 95% confidence interval: 0.94–1.01) were not significantly associated with CRC risk. The sensitivity analyses yielded similar results.

Conclusions

Our study does not support a causal relationship between genetic risk scores for age at menarche and age at menopause and CRC risk.

A Mixed-Effects Model for Powerful Association Tests in Integrative Functional Genomics

Genome-wide association studies (GWASs) have successfully identified thousands of genetic variants for many complex diseases; however, these variants explain only a small fraction of the heritability. Recently, genetic association studies that leverage external transcriptome data have received much attention and shown promise for discovering novel variants. One such approach, PrediXcan, is to use predicted gene expression through genetic regulation. However, there are limitations in this approach. The predicted gene expression may be biased, resulting from regularized regression applied to moderately sample-sized reference studies. Further, some variants can individually influence disease risk through alternative functional mechanisms besides expression. Thus, testing only the association of predicted gene expression as proposed in PrediXcan will potentially lose power. To tackle these challenges, we consider a unified mixed effects model that formulates the association of intermediate phenotypes such as imputed gene expression through fixed effects, while allowing residual effects of individual variants to be random. We consider a set-based score testing framework, MiST (mixed effects score test), and propose two data-driven combination approaches to jointly test for the fixed and random effects. We establish the asymptotic distributions, which enable rapid calculation of p values for genome-wide analyses, and provide p values for fixed and random effects separately to enhance interpretability over GWASs. Extensive simulations demonstrate that our approaches are more powerful than existing ones. We apply our approach to a large-scale GWAS of colorectal cancer and identify two genes, POU5F1B and ATF1, which would have otherwise been missed by PrediXcan, after adjusting for all known loci.

Inherited variation in circadian rhythm genes and risks of prostate cancer and three other cancer sites in combined cancer consortia

Circadian disruption has been linked to carcinogenesis in animal models, but the evidence in humans is inconclusive. Genetic variation in circadian rhythm genes provides a tool to investigate such associations. We examined associations of genetic variation in nine core circadian rhythm genes and six melatonin pathway genes with risk of colorectal, lung, ovarian and prostate cancers using data from the Genetic Associations and Mechanisms in Oncology (GAME-ON) network. The major results for prostate cancer were replicated in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial, and for colorectal cancer in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). The total number of cancer cases and controls was 15,838/18,159 for colorectal, 14,818/14,227 for prostate, 12,537/17,285 for lung and 4,369/9,123 for ovary. For each cancer site, we conducted gene-based and pathway-based analyses by applying the summary-based Adaptive Rank Truncated Product method (sARTP) on the summary association statistics for each SNP within the candidate gene regions. Aggregate genetic variation in circadian rhythm and melatonin pathways were significantly associated with the risk of prostate cancer in data combining GAME-ON and PLCO, after Bonferroni correction (ppathway  < 0.00625). The two most significant genes were NPAS2 (pgene  = 0.0062) and AANAT (pgene  = 0.00078); the latter being significant after Bonferroni correction. For colorectal cancer, we observed a suggestive association with the circadian rhythm pathway in GAME-ON (ppathway  = 0.021); this association was not confirmed in GECCO (ppathway  = 0.76) or the combined data (ppathway  = 0.17). No significant association was observed for ovarian and lung cancer. These findings support a potential role for circadian rhythm and melatonin pathways in prostate carcinogenesis. Further functional studies are needed to better understand the underlying biologic mechanisms.

Intraepithelial CD94+ tumor-infiltrating lymphocytes in a context of HLA-E overexpression as a new immune checkpoint to predict prognosis in colorectal carcinomas

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Background: A better understanding of the immune-modulating interactions between tumor cells and immune cells underlying the balance between immune control and immune resistance in colorectal cancer (CRC) is crucial for the design of immunotherapies. We have previously demonstrated that overexpression of the human MHC class Ib molecule - HLA-E/β2 microglobulin - by tumor cells in CRC was associated with an unfavorable prognosis, suggesting its involvement in immune escape. However, the specific receptor of HLA-E/β2m - CD94/NKG2A, inhibitory or CD94/NKG2C, activating - expressed by tumor-infiltrating lymphocytes (TIL), as well as the influence of the microsatellite status in HLA-E/β2m overexpression, remain unknown. Methods: We investigated in the primary tumor of 245 CRC patients 1) the association of HLA-E/β2m overexpression and the density of CD94+ intraepithelial TIL (IEL-TIL) with the microsatellite status, 2) the nature of CD94+ TIL and the receptor expressed - CD94/NKG2A or CD94/NKG2C - and 3) the prognostic influence of CD94+ IEL-TIL. Results: HLA-E/β2m was preferentially overexpressed in MSI compared with MSS CRC (44,6 % vs 18,4 % respectively, p = 0.0001), and significantly associated with a high density of CD94+ IEL-TIL in MSI (0,9% in HLA-E/β2m+ vs 0,2% in HLA-E/β2m– CRC, p = 0,001), and in MSS CRC (0,38% vs 0,15%, p < 0,0001). These CD94+ TIL mostly corresponded to CD8+ αβ T cells preferentially expressing the inhibitory NKG2A chain. Finally, a high density of CD94+ IEL-TIL was independently associated with a worse OS (p = 0.03). Conclusions: These results strongly suggest that HLA-E/β2m - CD94/NKG2A interactions, preferentially up-regulated in MSI CRC, represent a promising inhibitory immune checkpoint. From a clinical point of view, this inhibitory immune checkpoint could be blocked by the new anti-NKG2A monoclonal antibody.

Potential therapeutic target for PD1/PDL1 blockade in microsatellite medullary carcinomas based on PDL1 expression by tumor cells and infiltration by numerous PD1+ T lymphocytes

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Background: PD1/PDL1 blockade showed therapeutic efficacy in only microsatellite (MSI) colorectal carcinomas (CRC), however, the profile of PDL1 and PD1 expression in CRC is only partially described. Methods: We thus analyzed on FFPE whole-tissue sections of 80 CRC, the expression profile of PDL1 by tumor and/or immune cells by immunohistochemistry (clone E1L3N) depending on the MSI status and the histological subtype, and correlated to the density of PD1+ and Tbet+ (able to secrete IFNg known to induce PDL1) tumor-infiltrating lymphocytes (TIL). Results: 78% of MSI CRC (32/41) overexpressed PDL1 either by tumor or immune cells versus 46% of MSS CRC (18/39) (p 0.005). This overexpression was heterogeneous within the same tumor in most of cases. Among MSI CRC, PDL1 was preferentially overexpressed in medullary carcinomas (MC, 19/21, 90%) compared with 65% (13/20) in non medullary adenocarcinomas (p 0.06). PDL1 expression by tumor cells was only observed in MSI CRC (19/41, 46% with PDL1 expression in more than 5% of tumor cells – score 1), and preferentially in MC (57% vs 5% in no medullary adenocarcinomas, with PDL1 expression in more than 50% of tumor cells – score 3, p 0.0005). Conversely, PDL1 expression by immune cells was observed in MSI CRC (23/41, 56% with PDL1 expression by more than 5 sheets of 50 positive cells) but also in MSS CRC (18/39, 43%) (p 0.5). The density of PD1+ cells was significantly correlated to the PDL1 expression, as well as the density of Tbet+ TIL. Conclusions: PDL1 expression is 1) heterogeneous in CRC, among CRC but also within the same tumor, 2) preferentially observed in MSI CRC (78%), especially in MC (90%), where PDL1 is expressed by tumor cells, 3) correlated with the density of PD1+ or Tbet+ TIL, and 4) observed in a significant proportion of MSS CRC (46%) by immune cells only. From a clinical point of view, PDL1 expression has to be determined at best in full tissue section and besides its preferential expression in MSI CRC, its significant frequency and expression profil (only by immune cells) in MSS CRC should be taken into account in the future clinical trials testing the efficacy of anti-PD1/PDL1 antibodies.

PD-L1 and PD-1 expression profile depending on the microsatellite status and the histological subtype in colorectal carcinomas

590

Background: PD-1/PD-L1 blockade showed therapeutic efficacy in only microsatellite (MSI) colorectal carcinomas (CRC), however, the profile of PD-L1 and PD-1 expression in CRC is only partially described. Methods: We thus analyzed on FFPE whole-tissue sections of 80 CRC, the expression profile of PD-L1 by tumor and/or immune cells by immunohistochemistry (clone E1L3N) depending on the MSI status and the histological subtype, and correlated to the density of PD-1+ and Tbet+ (able to secrete IFNg known to induce PD-L1) tumor-infiltrating lymphocytes (TIL). Results: 78% of MSI CRC (32/41) overexpressed PD-L1 either by tumor or immune cells versus 46% of MSS CRC (18/39) (p 0.005). This overexpression was heterogeneous within the same tumor in most of cases. Among MSI CRC, PD-L1 was preferentially overexpressed in medullary carcinomas (MC, 19/21, 90%) compared with 65% (13/20) in non-medullary adenocarcinomas (p 0.06). PD-L1 expression by tumor cells was only observed in MSI CRC (19/41, 46% with PD-L1 expression in more than 5% of tumor cells – score 1), and preferentially in MC (57% vs 5% in no medullary adenocarcinomas, with PD-L1 expression in more than 50% of tumor cells – score 3, p 0.0005). Conversely, PD-L1 expression by immune cells was observed in MSI CRC (23/41, 56% with PD-L1 expression by more than 5 sheets of 50 positive cells) but also in MSS CRC (18/39, 43%) (p 0.5). The density of PD-1+ cells was significantly correlated to the PD-L1 expression, as well as the density of Tbet+ TIL. Conclusions: PD-L1 expression is 1) heterogeneous in CRC, among CRC but also within the same tumor, 2) preferentially observed in MSI CRC (78%), especially in MC (90%), where PD-L1 is expressed by tumor cells, 3) correlated with the density of PD-1+ or T-bet+ TIL, and 4) observed in a significant proportion of MSS CRC (46%) by immune cells only. From a clinical point of view, PD-L1 expression has to be determined at best in full tissue section and besides its preferential expression in MSI CRC, its significant frequency and expression profile (only by immune cells) in MSS CRC should be taken into account in the future clinical trials testing the efficacy of anti-PD-1/PD-L1 antibodies.

Telomere structure and maintenance gene variants and risk of five cancer types

Telomeres cap chromosome ends, protecting them from degradation, double-strand breaks, and end-to-end fusions. Telomeres are maintained by telomerase, a reverse transcriptase encoded by TERT, and an RNA template encoded by TERC. Loci in the TERT and adjoining CLPTM1L region are associated with risk of multiple cancers. We therefore investigated associations between variants in 22 telomere structure and maintenance gene regions and colorectal, breast, prostate, ovarian, and lung cancer risk. We performed subset-based meta-analyses of 204,993 directly-measured and imputed SNPs among 61,851 cancer cases and 74,457 controls of European descent. Independent associations for SNP minor alleles were identified using sequential conditional analysis (with gene-level p value cutoffs ≤3.08 × 10-5 ). Of the thirteen independent SNPs observed to be associated with cancer risk, novel findings were observed for seven loci. Across the DCLRE1B region, rs974494 and rs12144215 were inversely associated with prostate and lung cancers, and colorectal, breast, and prostate cancers, respectively. Across the TERC region, rs75316749 was positively associated with colorectal, breast, ovarian, and lung cancers. Across the DCLRE1B region, rs974404 and rs12144215 were inversely associated with prostate and lung cancers, and colorectal, breast, and prostate cancers, respectively. Near POT1, rs116895242 was inversely associated with colorectal, ovarian, and lung cancers, and RTEL1 rs34978822 was inversely associated with prostate and lung cancers. The complex association patterns in telomere-related genes across cancer types may provide insight into mechanisms through which telomere dysfunction in different tissues influences cancer risk.

Cross-Cancer Genome-Wide Analysis of Lung, Ovary, Breast, Prostate, and Colorectal Cancer Reveals Novel Pleiotropic Associations

Identifying genetic variants with pleiotropic associations can uncover common pathways influencing multiple cancers. We took a two-stage approach to conduct genome-wide association studies for lung, ovary, breast, prostate, and colorectal cancer from the GAME-ON/GECCO Network (61,851 cases, 61,820 controls) to identify pleiotropic loci. Findings were replicated in independent association studies (55,789 cases, 330,490 controls). We identified a novel pleiotropic association at 1q22 involving breast and lung squamous cell carcinoma, with eQTL analysis showing an association with ADAM15/THBS3 gene expression in lung. We also identified a known breast cancer locus CASP8/ALS2CR12 associated with prostate cancer, a known cancer locus at CDKN2B-AS1 with different variants associated with lung adenocarcinoma and prostate cancer, and confirmed the associations of a breast BRCA2 locus with lung and serous ovarian cancer. This is the largest study to date examining pleiotropy across multiple cancer-associated loci, identifying common mechanisms of cancer development and progression. Cancer Res; 76(17); 5103-14. ©2016 AACR.

Fine-Mapping of Common Genetic Variants Associated with Colorectal Tumor Risk Identified Potential Functional Variants

Genome-wide association studies (GWAS) have identified many common single nucleotide polymorphisms (SNPs) associated with colorectal cancer risk. These SNPs may tag correlated variants with biological importance. Fine-mapping around GWAS loci can facilitate detection of functional candidates and additional independent risk variants. We analyzed 11,900 cases and 14,311 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium and the Colon Cancer Family Registry. To fine-map genomic regions containing all known common risk variants, we imputed high-density genetic data from the 1000 Genomes Project. We tested single-variant associations with colorectal tumor risk for all variants spanning genomic regions 250-kb upstream or downstream of 31 GWAS-identified SNPs (index SNPs). We queried the University of California, Santa Cruz Genome Browser to examine evidence for biological function. Index SNPs did not show the strongest association signals with colorectal tumor risk in their respective genomic regions. Bioinformatics analysis of SNPs showing smaller P-values in each region revealed 21 functional candidates in 12 loci (5q31.1, 8q24, 11q13.4, 11q23, 12p13.32, 12q24.21, 14q22.2, 15q13, 18q21, 19q13.1, 20p12.3, and 20q13.33). We did not observe evidence of additional independent association signals in GWAS-identified regions. Our results support the utility of integrating data from comprehensive fine-mapping with expanding publicly available genomic databases to help clarify GWAS associations and identify functional candidates that warrant more onerous laboratory follow-up. Such efforts may aid the eventual discovery of disease-causing variant(s).

Pleiotropic effects of genetic risk variants for other cancers on colorectal cancer risk: PAGE, GECCO and CCFR consortia

OBJECTIVE

Genome-wide association studies have identified a large number of single nucleotide polymorphisms (SNPs) associated with a wide array of cancer sites. Several of these variants demonstrate associations with multiple cancers, suggesting pleiotropic effects and shared biological mechanisms across some cancers. We hypothesised that SNPs previously associated with other cancers may additionally be associated with colorectal cancer. In a large-scale study, we examined 171 SNPs previously associated with 18 different cancers for their associations with colorectal cancer.

DESIGN

We examined 13 338 colorectal cancer cases and 40 967 controls from three consortia: Population Architecture using Genomics and Epidemiology (PAGE), Genetic Epidemiology of Colorectal Cancer (GECCO), and the Colon Cancer Family Registry (CCFR). Study-specific logistic regression results, adjusted for age, sex, principal components of genetic ancestry, and/or study specific factors (as relevant) were combined using fixed-effect meta-analyses to evaluate the association between each SNP and colorectal cancer risk. A Bonferroni-corrected p value of 2.92×10(-4) was used to determine statistical significance of the associations.

RESULTS

Two correlated SNPs--rs10090154 and rs4242382--in Region 1 of chromosome 8q24, a prostate cancer susceptibility region, demonstrated statistically significant associations with colorectal cancer risk. The most significant association was observed with rs4242382 (meta-analysis OR=1.12; 95% CI 1.07 to 1.18; p=1.74×10(-5)), which also demonstrated similar associations across racial/ethnic populations and anatomical sub-sites.

CONCLUSIONS

This is the first study to clearly demonstrate Region 1 of chromosome 8q24 as a susceptibility locus for colorectal cancer; thus, adding colorectal cancer to the list of cancer sites linked to this particular multicancer risk region at 8q24.

Identification of two novel mutations in Shh long-range regulator associated with familial pre-axial polydactyly

Pre-axial polydactyly type II (PPDII, MIM #174500), Werner mesomelic syndrome (MIM %188770) and Haas polysyndactyly (MIM #186200) are a group of closely related conditions caused by mutations in a long-range Sonic hedgehog (SHH, MIM *600725) regulator called ZRS. To date, 19 point mutations, 10 duplications and 1 triplication of the ZRS associated with those pre-axial polydactylies have been reported in humans, mice, cats and chickens. Some of these have been shown to cause ectopic expression of Shh in the limb bud in mice, leading to a polydactylous phenotype, but the precise mechanism by which ZRS mutations generate this phenotype remains unknown. We present two PPDII families with fully penetrant point mutations in ultra-conserved predicted binding sites for transcription factors SOX9 and PAX3, two possible candidates for regulating SHH expression. Screening for point mutations or copy-number variation of the ZRS, high-resolution array-CGH, and screening of other conserved non-coding sequences (CNS) surrounding SHH in a third family are negative. This is the sixth PPDII pedigree with possible linkage to 7q36 that presents with no detectable ZRS mutation. We hypothesize that another nearby regulatory sequence, or an undetected position effect between ZRS and SHH, could be responsible for negative familial cases linked to 7q36.

Prevalence, biological phenotype and genotype in moderate/mild hemophilia A with discrepancy between one-stage and chromogenic factor VIII activity

BACKGROUND

In most laboratories, the severity of hemophilia A is assessed by the factor VIII activity (FVIII:C) one-stage assay. However, comparisons of these results with those of two-stage assays can reveal discrepancies and suggest misdiagnosis.

PATIENTS/METHODS

In this monocentric study, we measured FVIII:C with two methods (one-stage chronometric and chromogenic assays) in 307 (173 families) patients with moderate/mild hemophilia A. To compare results, we used a chronometric/chromogenic ratio. Discrepancy was defined as a ratio < 0.5 or > 1.5. We studied their putative involvement at known FVIII functional sites, their interspecies conservation status, and their spatial position within the FVIII structure.

RESULTS

Thirty-six patients from 17 families exhibited a discrepancy between the two assays: 12 (6.9%) families had a low ratio (< 0.5), and five (2.9%) families had a high ratio (> 1.5). Qualitative deficiency was diagnosed in about 16% of the families. Molecular studies were performed in 15 of these 17 families, resulting in each case in the identification of missense mutations, including three novel mutations. We were further able to propose a pathophysiologic explanation.

CONCLUSIONS

In this monocentric study, we have demonstrated a discrepancy between FVIII:C assay results in 10% of families with moderate/mild hemophilia A. The prevalence of 'inverse' discrepancy (i.e. low chronometric/chromogenic ratio) is high as compared with previous reports. We suggest that both FVIII:C assays are recommended in patients with moderate/mild hemophilia A for a complete biological phenotype. This could also improve our knowledge of the FVIII structure-function relationships.

Trypsinogen copy number mutations in patients with idiopathic chronic pancreatitis

BACKGROUND & AIMS

We have recently reported that the triplication of a approximately 605 kilobase segment containing the PRSS1 (encoding cationic trypsinogen) and PRSS2 (encoding anionic trypsinogen) genes causes hereditary pancreatitis. Here we went further to investigate whether this copy number mutation could account for some unidentified French white patients with idiopathic chronic pancreatitis (ICP) or familial chronic pancreatitis (FCP) as well as Indian patients with tropical calcific pancreatitis (TCP).

METHODS

Patients and controls were screened by means of previously described quantitative fluorescent multiplex polymerase chain reaction and/or genotyping of the microsatellite marker rs3222967.

RESULTS

The approximately 605 kilobase triplication and a novel duplication (confirmed by fluorescence in situ hybridization) of the trypsinogen locus were detected in 10 and 2 of 202 ICP patients, respectively (age of disease onset, <or=20 years) but were absent in 282 French controls. In addition, the duplication mutation was found in 2 of 1044 ICP patients whose age of disease onset was >20 years. However, the 2 trypsinogen copy number mutations were observed in neither 103 FCP patients nor 268 Indian TCP patients.

CONCLUSIONS

Our findings revealed the molecular basis of 6% of the young ICP patients and further demonstrated that chronic pancreatitis is a genomic disorder. Our findings also add to the mounting evidence showing that trypsinogen gene mutations do not appear to play an important role in the pathogenesis of TCP in the Indian population. Finally, a dividend of this study is that we have provided convincing evidence to show that all 5 previously described copy number variations involving PRSS1 or/and PRSS2 are artifacts.

Genome-wide association scan identifies a colorectal cancer susceptibility locus on chromosome 8q24

Using a multistage genetic association approach comprising 7,480 affected individuals and 7,779 controls, we identified markers in chromosomal region 8q24 associated with colorectal cancer. In stage 1, we genotyped 99,632 SNPs in 1,257 affected individuals and 1,336 controls from Ontario. In stages 2-4, we performed serial replication studies using 4,024 affected individuals and 4,042 controls from Seattle, Newfoundland and Scotland. We identified one locus on chromosome 8q24 and another on 9p24 having combined odds ratios (OR) for stages 1-4 of 1.18 (trend; P = 1.41 x 10(-8)) and 1.14 (trend; P = 1.32 x 10(-5)), respectively. Additional analyses in 2,199 affected individuals and 2,401 controls from France and Europe supported the association at the 8q24 locus (OR = 1.16, trend; 95% confidence interval (c.i.): 1.07-1.26; P = 5.05 x 10(-4)). A summary across all seven studies at the 8q24 locus was highly significant (OR = 1.17, c.i.: 1.12-1.23; P = 3.16 x 10(-11)). This locus has also been implicated in prostate cancer.

Germline RET V804M mutation associated with multiple endocrine neoplasia type 2A

Rare mutation

High incidence of N and K-Ras activating mutations in multiple myeloma and primary plasma cell leukemia at diagnosis

Using allele-specific amplification method (ARMS), a highly sensitive one-stage allele-specific PCR, we have evaluated the incidence of NRAS and KRAS2 activating mutations (codons 12, 13, and 61) in 62 patients with either monoclonal gammopathy of undetermined significance (MGUS) or multiple myeloma (MM), primary plasma-cell leukemia (P-PCL), and also in human myeloma cell lines (HMCL). NRAS and/or KRAS2 mutations were found in 54.5% of MM at diagnosis (but in 81% at the time of relapse), in 50% of P-PCL, and in 50% of 16 HMCL. In contrast, the occurrence of such mutations was very low in MGUS and indolent MM (12.50%). Of note, KRAS2 mutations were always more frequent than NRAS. The validity of the technique was assessed by direct sequencing of cell lines and of some patients. Multiple mutations found in two patients were confirmed by subcloning exon PCR amplification products, testing clones with our method, and sequencing them. Thus, these early mutations could play a major role in the oncogenesis of MM and P-PCL.

Familial medullary thyroid carcinoma with noncysteine ret mutations: phenotype-genotype relationship in a large series of patients

Familial medullary thyroid carcinoma only is related to germline mutations in the protooncogene RET, mainly in exons 10, whereas noncysteine mutations (exons 13-15) are considered infrequent. We analyzed 148 patients from 47 familial medullary thyroid carcinoma only families, and we found noncysteine RET mutations in 59.5% of these families. Of the index cases with noncysteine mutations, 43.4% presented with a multinodular goiter and high basal calcitonin; they were older at diagnosis than those with mutation in exon 10 and had more multifocal medullary thyroid carcinoma, but no difference in size, bilaterality, presence of C cell hyperplasia, or nodal metastases was found. Gene carriers with noncysteine RET mutations had a lower incidence of medullary thyroid carcinoma (78.2% vs. 94.1%) than those with mutation in exon 10; 20.2% had C cell hyperplasia only, although thyroidectomized at an older age. In conclusion, familial medullary thyroid carcinoma with noncysteine RET mutations are not infrequent and are overrepresented in presumed sporadic medullary thyroid carcinoma, suggesting that RET analysis should routinely be extended to exons 13, 14, and 15. The phenotype is characterized by a late onset of the disease, suggesting a delayed appearance of C cell disease rather than a less aggressive form. In familial medullary thyroid carcinoma gene carriers, the optimal timing for thyroidectomy remains controversial. Based on these data, we propose that surgery should be performed before elevation of the basal calcitonin level, potentially as soon as the pentagastrin test becomes abnormal.

Microsatellite haplotypes associations with 5 CFTR mutations in "Grande Brière", an isolate located in southern Brittany

The variability at three microsatellites in the Cystic Fibrosis Transmembrane Conductance Regulator Gene (CFTR) locus has been studied for frequent mutations encountered in an isolated population of "Grande Brière", a small region located in Southern Brittany. Fluorescent multiplex PCR of these microsatellites were assayed in 16 Cystic Fibrosis (CF) families carrying 5 different mutations. The four most frequent haplotypes on df508 chromosomes were the same as those found in Northern France and Europe but the distribution of these haplotypes provides new enlightenment on the population origin of this insular community.