[Show abstract][Hide abstract] ABSTRACT: Despite previous studies, uncertainty has persisted about the role of thymidylate synthase (TS) and p53 status as markers of prognosis in colorectal cancer (CRC).
A total of 967 patients accrued to a large adjuvant trial in CRC were included in a prospectively planned molecular substudy, and of them, 59% had rectal cancer and about 90% received adjuvant chemotherapy (either systemically or randomly allocated to intraportal 5-fluorouracil infusion or both). TS and p53 status were determined, blinded to any clinical data, by immunohistochemistry using a validated polyclonal antibody or the DO-7 clone, respectively, and their relationships with overall survival were examined.
High TS expression was observed in 58% and overexpression of p53 in 60% of tumours. TS expression correlated with tumour stage, and p53 overexpression, with rectal cancers. There was no evidence that either marker was significantly associated with survival by either univariate (TS hazard ratio (HR) = 0.94, 95% CI 0.76-1.18 and P = 0.6 and p53 HR = 0.98, 95% CI 0.78-1.23 and P = 0.9) or multivariate analyses (TS HR = 0.99, 95% CI 0.79-1.25 and P = 0.9 and p53 HR = 0.98, 95% CI 0.78-1.23 and P = 0.8).
Neither TS nor p53 expression has significant prognostic value in the adjuvant setting of CRC.
[Show abstract][Hide abstract] ABSTRACT: Peutz-Jeghers syndrome (PJS) is caused by germline STK11 mutations and characterised by gastrointestinal polyposis. Although small bowel intussusception is a recognised complication of PJS, risk varies between patients.
To analyse the time to onset of intussusception in a large series of PJS probands.
STK11 mutation status was evaluated in 225 PJS probands and medical histories of the patients reviewed.
135 (60%) of the probands possessed a germline STK11 mutation; 109 (48%) probands had a history of intussusception at a median age of 15.0 years but with wide variability (range 3.7 to 45.4 years). Median time to onset of intussusception was not significantly different between those with identified mutations and those with no mutation detected, at 14.7 years and 16.4 years, respectively (log-rank test of difference, chi(2) = 0.58, with 1df; p = 0.45). Similarly no differences were observed between patient groups on the basis of the type or site of STK11 mutation.
The risk of intussusception in PJS is not influenced by STK11 mutation status.
Full-text · Article · Sep 2006 · Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Although an increased cancer risk in Peutz-Jeghers syndrome is established, data on the spectrum of tumors associated with the disease and the influence of germ-line STK11/LKB1 (serine/threonine kinase) mutation status are limited.
We analyzed the incidence of cancer in 419 individuals with Peutz-Jeghers syndrome, and 297 had documented STK11/LKB1 mutations.
Ninety-six cancers were found among individuals with Peutz-Jeghers syndrome. The risk for developing cancer at ages 20, 30, 40, 50, 60, and 70 years was 2%, 5%, 17%, 31%, 60%, and 85%, respectively. The most common cancers represented in this analysis were gastrointestinal in origin, gastroesophageal, small bowel, colorectal, and pancreatic, and the risk for these cancers at ages 30, 40, 50, and 60 years was 1%, 9%, 15%, and 33%, respectively. In women with Peutz-Jeghers syndrome, the risk of breast cancer was substantially increased, being 8% and 31% at ages 40 and 60 years, respectively. Kaplan-Meier analysis showed that cancer risks were similar in Peutz-Jeghers syndrome patients with identified STK11/LKB1 mutations and those with no detectable mutation (log-rank test of difference chi2 = 0.62; 1 df; P = 0.43). Furthermore, the type or site of STK11/LKB1 mutation did not significantly influence cancer risk.
The results from our study provide quantitative information on the spectrum of cancers and risks of specific cancer types associated with Peutz-Jeghers syndrome.
No preview · Article · Jun 2006 · Clinical Cancer Research
[Show abstract][Hide abstract] ABSTRACT: Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant cancer predisposition syndrome characterised by oro-facial pigmentation and hamartomatous polyposis of the gastrointestinal tract. A causal germline mutation in STK11 can be identified in 30% to 80% of PJS patients.
Here we report the comprehensive mutational analysis of STK11 in 38 PJS probands applying conventional PCR based mutation detection methods and the recently introduced MLPA (multiplex ligation dependent probe amplification) technique developed for the identification of exonic deletions/duplications.
Nineteen of 38 probands (50%) had detectable point mutations or small scale deletions/insertions and six probands (16%) had genomic deletions encompassing one or more STK11 exons.
These findings demonstrate that exonic STK11 deletions are a common cause of PJS and provide a strong rationale for conducting a primary screen for such mutations in patients.
Full-text · Article · May 2006 · Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Germline mutations or large-scale deletions in the coding region and splice sites of STK11/LKB1 do not account for all cases of Peutz-Jeghers syndrome (PJS). It is conceivable that, on the basis of data from other diseases, inherited variation in promoter elements of STK11/LKB1 may cause PJS.
Phylogenetic foot printing and transcription factor binding site prediction of sequence 5' to the coding sequence of STK11/LKB1 was performed to identify non-coding sequences of DNA indicative of regulatory elements. A series of 33 PJS cases in whom no mutation in STK11/LKB1 could be identified were screened for sequence changes in the putative promoter defined by nucleotides -1090 to -1472. Two novel sequence changes were identified, but were found to be present in healthy individuals.
These findings indicate that promoter sequence changes are unlikely to contribute to PJS.
[Show abstract][Hide abstract] ABSTRACT: Germ-line mutations in the serine-threonine kinase gene STK11 (LKB1) cause Peutz-Jeghers syndrome (PJS), a rare autosomal dominantly inherited disease, characterized by hamartomatous polyposis and mucocutaneous pigmentation. STK11 mutations only account for about half of PJS cases, and a second disease locus has been proposed at chromosome segment 19q13.4 on the basis of genetic linkage analysis in one family. We identified a t(11;19)(q13;q13.4) in a PJS polyp arising from the small bowel in a female infant age 6 days. Because the breakpoint in 19q13.4 may disrupt the putative PJS disease gene mapping to this region, we mapped the breakpoint and analyzed DNA from the case and a series of STK11-negative PJS cases. Using two-color interphase fluorescence in situ hybridization, the breakpoint region was refined to a 0.5-Mb region within 19q13.4. Eight candidate genes mapping to the breakpoint region--U2AF2, EPN1, NALP4, NALP11, NALP5, ZNF444, PTPRH, and KIAA1811--were screened for mutations in germ-line and polyp DNA from the case and from 15 PJS cases that did not harbor germ-line STK11 mutations. No pathogenic mutations in the candidate genes were identified. This report provides further evidence of the existence of a second PJS disease locus at 19q13.4 and excludes involvement of eight candidate genes.
No preview · Article · Oct 2004 · Genes Chromosomes and Cancer
[Show abstract][Hide abstract] ABSTRACT: Variants of the melanocortin-1 receptor (MC1R) gene have been linked to sun-sensitive skin types and hair colour, and may independently play a role in susceptibility to cutaneous melanoma. To assess the role of MC1R variants in uveal melanoma, we have analysed a cohort of 350 patients for the changes within the major region of the gene displaying sequence variation. Eight variants were detected - V60L, D84E, V92M, R151C, I155T, R160W, R163Q and D294H - 63% of these patients being hetero- or homozygous for at least one variant. Standard melanoma risk factor data were available on 119 of the patients. MC1R variants were significantly associated with hair colour (P=0.03) but not skin or eye colour. The frequency of the variants detected in the 350 patients was comparable with those in the general population, and comparison of the cumulative tumour distribution by age at diagnosis in carriers and noncarriers provided no evidence that MC1R variants confer an increased risk of uveal melanoma. We interpret the data as indicating that MC1R variants do not appear to be major determinants of susceptibility to uveal melanoma.
Full-text · Article · Dec 2003 · British Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Germline mutations in the LKB1/STK11 tumour suppressor gene cause Peutz-Jeghers syndrome (PJS), a rare dominant disorder. In addition to typical hamartomatous gastrointestinal polyps and pigmented perioral lesions, PJS is associated with an increased risk of tumours at multiple sites. Follow-up information on carriers is limited and genetic heterogeneity makes counselling and management in PJS difficult. Here we report the analysis of the LKB1/STK11 locus in a series of 33 PJS families, and estimation of cancer risks in carriers and noncarriers. Germline mutations of LKB1/STK11 were identified in 52% of cases. This observation reinforces the hypothesis of a second PJS locus. In carriers of LKB1/STK11 mutations, the risk of cancer was markedly elevated. The risk of developing any cancer in carriers by age 65 years was 47% (95% CI: 27-73%) with elevated risks of both gastrointestinal and breast cancer. PJS with germline mutations in LKB1/STK11 are at a very high relative and absolute risk of multiple gastrointestinal and nongastrointestinal cancers. To obtain precise estimates of risk associated with PJS requires further studies of genotype-phenotype especially with respect to LKB1/STK11 negative cases, as this group is likely to be heterogeneous.
Full-text · Article · Aug 2003 · British Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Reports suggest that a subset of uveal melanoma is familial. The association of uveal melanoma with breast and ovarian cancer and the increased risk in BRCA2-linked families implicates germline BRCA2 mutations as the cause of a subset of uveal melanomas. Similarly, the association between cutaneous and uveal melanomas in some families, coupled with the high frequency of somatic deletions of the INK4A-ARF locus in uveal melanomas, strongly suggests that mutations in P16(INK4A) and P15 account for a proportion of uveal melanomas.
To examine this proposition, a systematically ascertained series of 385 patients with uveal melanoma were screened for germline mutations in BRCA2, P16(INK4A), P14(ARF), and P15.
One patient was found to harbor a Gly35Ala substitution in exon 1alpha of P16(INK4A), which has previously been reported to be pathogenic. No mutations were detected in P14(ARF) or P15. None of the patients harbored germline nucleotide changes that lead to truncation or that create or disrupt consensus splice sites of BRCA2 or missense variants with clear pathogenic potential.
These findings suggest that less than 2% of cases of uveal melanoma can be ascribed to germline mutations in BRCA2, P16(INK4A), P14(ARF), or P15. It is likely that mutations in other genes contribute to an inherited predisposition to uveal melanoma.
No preview · Article · Mar 2003 · Investigative Ophthalmology & Visual Science
[Show abstract][Hide abstract] ABSTRACT: Coeliac disease shows a strong genetic predisposition involving HLA-DQ2 and non-HLA components. The CD28 cell surface molecule, encoded by CD28, represents a potential candidate coeliac disease susceptibility gene. Furthermore, some studies have demonstrated linkage to the CD28/CTLA4 gene region. To investigate whether germline mutations in CD28 contribute to coeliac disease susceptibility, we have carried out a comprehensive analysis of the gene in Swedish patients with biopsy-proven disease.
Blood samples were collected from 52 children with biopsy proven coeliac disease attending one Swedish centre. DNA was extracted from lymphocytes and all exons and intron-exon boundaries of CD28 were screened for mutations. Analysis of CD28 was undertaken by a combination of conformation specific gel electrophoresis and direct sequencing.
Three sequence variants were identified: a synonymous G-->4A substitution at position 3 of codon 35 encoding alanine, a synonymous G-->A substitution at position 3 of codon 70 encoding glycine, and a T-->C substitution at nucleotide +17 of intron 3. No pathogenic variants were detected.
There is no evidence from this study that mutations in CD28, which lead to an altered protein, contribute to coeliac disease susceptibility.
No preview · Article · Jun 2002 · Scandinavian Journal of Gastroenterology
[Show abstract][Hide abstract] ABSTRACT: Uterine leiomyomata (fibroids) are common and clinically important tumors, but little is known about their etiology and pathogenesis1, 2, 3. We previously mapped a gene that predisposes to multiple fibroids, cutaneous leiomyomata and renal cell carcinoma to chromosome 1q42.3−q43 (refs 4−6). Here we show, through a combination of mapping critical recombinants, identifying individuals with germline mutations and screening known and predicted transcripts, that this gene encodes fumarate hydratase, an enzyme of the tricarboxylic acid cycle. Leiomyomatosis-associated mutations are predicted to result in absent or truncated protein, or substitutions or deletions of highly conserved amino acids. Activity of fumarate hydratase is reduced in lymphoblastoid cells from individuals with leiomyomatosis. This enzyme acts as a tumor suppressor in familial leiomyomata, and its measured activity is very low or absent in tumors from individuals with leiomyomatosis. Mutations in FH also occur in the recessive condition fumarate hydratase deficiency7, 8, 9, 10, 11, and some parents of people with this condition are susceptible to leiomyomata. Thus, heterozygous and homozygous or compound heterozygous mutants have very different clinical phenotypes. Our results provide clues to the pathogenesis of fibroids and emphasize the importance of mutations of housekeeping and mitochondrial proteins in the pathogenesis of common types of tumor12, 13, 14.
[Show abstract][Hide abstract] ABSTRACT: Susceptibility to coeliac disease involves HLA and non-HLA-linked genes. The CTLA4/CD28 gene region encodes immune regulatory T-cell surface molecules and is a strong candidate as a susceptibility locus. We evaluated CTLA4/CD28 in coeliac disease by genetic linkage and association and combined our findings with published studies through a meta-analysis. 116 multiplex families were genotyped across CTLA4/CD28 using eight markers. The contribution of CTLA4/CD28 to coeliac disease was assessed by non-parametric linkage and association analyses. Seven studies were identified that had evaluated the relationship between CTLA4/CD28 and coeliac disease and a pooled analysis of data undertaken. In our study there was evidence for a relationship between variation in the CTLA4/CD28 region and coeliac disease by linkage and association analyses. However, the findings did not attain formal statistical significance (p = 0.004 and 0.039, respectively). Pooling findings with published results showed significant evidence for linkage (504 families) and association (940 families): p values, 0.0001 and 0.0014 at D2S2214, respectively, and 0.0008 and 0.0006 at D2S116, respectively. These findings suggest that variation in the CD28/CTLA4 gene region is a determinant of coeliac disease susceptibility. Dissecting the sequence variation underlying this relationship will depend on further analyses utilising denser sets of markers.
No preview · Article · Mar 2002 · Annals of Human Genetics
[Show abstract][Hide abstract] ABSTRACT: A genetic susceptibility to coeliac disease is well established, involving HLA and non-HLA components. CTLA4 is an important regulator of T-cell function and some studies have suggested that sequence variation in the gene might be a determinant of disease susceptibility, although the evidence is conflicting.
Sixty-two children with biopsy-proven coeliac disease attending a single centre in Sweden were studied. All were genotyped for presence of the HLA-DQA1*0501, B 1*0201 alleles. Those who carried the HLA-DQ heterodimer (58/62) were genotyped for the +49 (A/G) exon I polymorphism. The transmission disequilibrium test (TDT) was used to test for association between coeliac disease and the A allele. The entire CTLA4 gene was screened for other sequence variants using a combination of conformation-sensitive gel electrophoresis and direct sequencing.
A significant association between the exon I polymorphism and coeliac disease was observed (P = 0.02). No other sequence variants in CTLA4 were detected.
This study provides further evidence that variation in CTLA4 is a determinant of coeliac disease susceptibility. If not mediated through the +49 (A/G) dimorphism directly, then the effect is likely to be mediated through linkage disequilibrium.
No preview · Article · Feb 2002 · Scandinavian Journal of Gastroenterology