Genetic heterogeneity in Peutz-Jeghers syndrome

De novo germline mutation in the serine-threonine kinase STK11/LKB1 gene associated with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease, characterized phenotypically by mucocutaneous pigmentation and hamartomatous polyposis. Affected patients are at an increased risk of developing gastrointestinal and other malignancies. Mutations in the STK11/LKB1 (LKB1) gene, which encodes for a serine-threonine kinase, have been identified as a genetic cause of PJS. Molecular analysis of the LKB1 gene in a simplex case of PJS revealed a substitution of cytosine (C) for guanine (G) at codon 246 in exon 6, resulting in the Tyr246X mutation. The nucleotide substitution leads to a premature stop codon at the 246 residue, predicting a truncated protein and presumed loss of kinase activity. Analysis of DNA from both parents of the PJS patient did not show this mutation, which is therefore a de novo mutation. We isolated DNA from microdissected gastrointestinal hamartomatous polyps in the PJS patient and investigated the loss of heterozygosity (LOH) at the LKB1 locus by real-time fluorescence polymerase chain reaction genotyping using a fluorescent resonance energy transfer technique. The results suggest a different mechanism from LOH in the formation of hamartomatous polyps.

The hamartomatous polyposis syndromes: a clinical and molecular review

Inherited forms of gastrointestinal cancer have been a major focus of study and advancement over the past decade. Familial adenomatous polyposis and hereditary nonpolyposis colon cancer are the two most common heritable colon cancer syndromes. Inherited polyposis syndromes are characterized by the dominant type of polyp (whether adenomatous or hamartomatous) present and by the polyp's location within the gastrointestinal tract. The hamartomatous polyposis syndromes are characterized by an overgrowth of cells native to the area in which they normally occur. They represent a small but appreciable number of the gastrointestinal inherited cancer predisposition syndromes; it is now known that many of these syndromes carry a substantial risk for developing colon cancer as well as other gastrointestinal and pancreatic cancers. Patients afflicted with these syndromes are also at significant risk for extraintestinal malignancies. Seven inherited hamartomatous polyposis syndromes have been described: familial juvenile polyposis syndrome, Cowden's syndrome, Bannayan-Ruvalcaba-Riley syndrome, Peutz-Jeghers syndrome, basal cell nevus syndrome, neurofibromatosis 1, and multiple endocrine neoplasia syndrome 2B. Hereditary mixed polyposis syndrome is a variant of juvenile polyposis characterized by both hamartomatous and adenomatous polyps. The hamartomatous syndromes occur at approximately 1/10th the frequency of the adenomatous syndromes and account for <1% of colorectal cancer in Northern America. While the diagnosis of these inherited syndromes is primarily clinical, genetic testing is now available for all six syndromes. However, there are a significant number of spontaneous mutations seen in each of the syndromes. The management of these patients necessitates a coordinated multidisciplinary approach. The purpose of this review is to characterize the clinical and pathological features of these syndromes and to review the targets of cancer surveillance. The molecular alterations responsible for the inherited hamartomatous polyposis syndromes will also be discussed.

LKB1, the multitasking tumour suppressor kinase

Mutations in the lkb1 gene are found in Peutz-Jeghers syndrome (PJS), with loss of heterozygosity or somatic mutations at the lkb1 locus, suggesting the gene product, the serine/threonine kinase LKB1, may function as a tumour suppressor. Patients with PJS are at a greater risk of developing cancers of epithelial tissue origin. It is widely accepted that the presence of hamartomatous polyps in PJS does not in itself lead to the development of malignancy. The signalling mechanisms that lead to these PJS related malignancies are not well understood. However, it is evident from the recent literature that LKB1 is a multitasking kinase, with unlimited potential in orchestrating cell activity. Thus far, LKB1 has been found to play a role in chromatin remodelling, cell cycle arrest, Wnt signalling, cell polarity, and energy metabolism, all of which may require the tumour suppressor function of this kinase and/or its catalytic activity.

Hereditary cancer syndromes of the skin

Hereditary cancer syndromes are a group of disorders characterized by a genetic susceptibility to the development of malignant tumors. Multiple cancers in the family or an abnormally early onset for the given cancer may suggest an underlying inherited predisposition. Awareness of their associated dermatologic manifestations can facilitate early detection of risk for neoplasms. This article provides an update on the clinical features, diagnostic criteria, and the use of genetic analysis in the detection of causative mutations of those hereditary cancer syndromes with cutaneous manifestations.

A novel STK11 germline mutation in two siblings with Peutz-Jeghers syndrome complicated by primary gastric cancer

Patients with Peutz-Jeghers syndrome (PJS) are known to be at risk of gastric cancer (GC), and the STK11 gene is a susceptibility gene for PJS. However, as no cases of PJS with GC in which a STK11 germline mutation has been identified have ever been reported and other susceptibility genes have also been suggested to be involved in PJS, the relation between STK11 germline mutations and GC in PJS is still unknown. In this study, we used sequencing analysis to investigate the STK11, CDH1, and TP53 loci for a germline mutation in two siblings with PJS with primary GC. A novel type of the STK11 germline mutation, c.890delG, encoding a truncated protein (p.Arg297fsX38) was identified, but no germline mutations of the CDH1 and TP53 genes were detected. No inactivation of the wild-type allele by somatic mutation or chromosomal deletion or hypermethylation at the 5'-CpG site of STK11 was detected in the GC. This is the first report of a STK11 germline mutation in a PJS patient with GC and should contribute to establishing correlations between the STK11 germline mutations and GC in PJS patients.

Genotype-phenotype correlations in Peutz-Jeghers syndrome

BACKGROUND AND AIMS

Peutz-Jeghers syndrome (PJS) is a dominantly inherited disorder often caused by mutations in STK11. Time to onset of symptoms was characterised for a large collection of individuals with PJS who had been tested for STK11 mutations and genotype-phenotype correlations were evaluated.

METHODS

We characterised mutations in 42 independent probands and also used a historical cohort design to study 51 individuals with Peutz-Jeghers syndrome who had completed self-administered questionnaires.

RESULTS

Mutations were detected in 22/32 (69%) probands with PJS and 0/10 probands referred to rule out PJS. Real-time PCR analysis to quantitate DNA failed to detect any large deletions in PJS participants without STK11 mutations. The median time to onset for gastrointestinal symptoms or polypectomy was 13 years of age but showed a wide variability. Gastric polyps were frequent in PJS participants, with a median age at onset of 16 years. Individuals with missense mutations had a significantly later time to onset of first polypectomy (p = 0.04) and of other symptoms compared with those participants either with truncating mutations or no detectable mutation.

CONCLUSION

STK11 mutation analysis should be restricted to individuals who meet PJS criteria or their close relatives. Direct sequencing of STK11 yields a high rate of point mutations in individuals who meet phenotypic PJS criteria. Individuals with missense mutations of STK11 typically had a later time to onset for PJS symptoms. The common occurrence of gastric polyps may facilitate chemopreventive studies for this disorder.

Molecular basis and diagnostics of hereditary colorectal cancers

Hereditary colorectal cancer syndromes are classified according to the presence of unusually large number of adenomatous or hamartomatous polyps, or their absence. The latter category includes hereditary non-polyposis colorectal cancer (Lynch syndrome) and its variants Muir-Torre and Turcot's syndromes. Adenomatous polyposis syndromes include familial adenomatous polyposis (FAP) and its variants, and the recently identified MYH- (mutY homolog)-associated polyposis. Hamartomatous polyposis syndromes include juvenile polyposis, Peutz-Jeghers syndrome, and Cowden syndrome, which is now included within the broader category 'PTEN (phosphatase and tensin homolog) hamartoma tumour syndrome'. Other syndromes such as the 'hereditary breast and colon cancer' and 'familial colorectal cancer' are not yet fully characterized. This review addresses the molecular basis of these syndromes with particular reference to the recent advances in this rapidly progressive field and the applications of such knowledge in diagnosis and management.

Mapping of a translocation breakpoint in a Peutz-Jeghers hamartoma to the putative PJS locus at 19q13.4 and mutation analysis of candidate genes in polyp andSTK11-negative PJS cases

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.

Preventive measures in Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a rare genetic disorder characterized by mucocutaneous melanin deposition, intestinal polyposis and an increased risk of cancer, both intestinal and extra-intestinal. We describe the current status of diagnosis and the methods by which the consequences of this condition can be minimized. A surveillance program for those diagnosed is also included.

Peutz-Jeghers syndrome: genetic screening

Peutz-Jeghers syndrome is an autosomal dominant condition leading to gastrointestinal polyps which often causes bowel obstruction. This syndrome also predisposes to gastrointestinal, pancreatic, breast, uterine and other malignancies. Prognosis is likely to be improved by the early commencement of appropriate surveillance programs. Diagnostic and predictive genetic testing is now possible in many families due to identification of causative mutations in the serine/threonine kinase (STK)-11 (also known as the LKB1) gene. Such testing has now entered routine clinical practice and will allow early recognition of the condition in young, at-risk family members.

Further observations on LKB1/STK11 status and cancer risk in Peutz-Jeghers syndrome

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.

LKB1, a protein kinase regulating cell proliferation and polarity

LKB1 is a serine-threonine protein kinase mutated in patients with an autosomal dominantly inherited cancer syndrome predisposing to multiple benign and malignant tumours, termed Peutz-Jeghers syndrome. Since its discovery in 1998, much research has focused on identification and characterisation of its cellular roles and analysing how LKB1 might be regulated. In this review we discuss exciting recent advances indicating that LKB1 functions as a tumour suppressor perhaps by controlling cell polarity. We also outline the current understanding of the molecular mechanisms by which LKB1 is regulated in vivo, through interaction with other proteins as well as by protein phosphorylation and prenylation.

Genetic screening for Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is clinically characterized by mucocutaneous melanocytic pigmentation, intestinal hamartomatous polyposis and a significantly increased risk of developing cancer. Mutations in the serine/threonine kinase (STK-)11 gene, also designated LKB1, are found in approximately 60% of cases of Peutz-Jeghers syndrome. There is evidence that genetic heterogeneity exists and gene(s) that have not yet been discovered may be responsible for the disease. Since most mutations in Peutz-Jeghers syndrome are null alleles and are dispersed throughout the entire STK11/LKB1 gene, the mutation screening strategies that combine approaches at both the DNA and RNA level are favored. Based upon the identification of novel mutational mechanisms, the impact of RNA-based screening for germinal STK11/LKB1 mutations in Peutz-Jeghers syndrome are specifically discussed.

Hereditary polyposis syndromes and hereditary non-polyposis colorectal cancer

Colorectal cancer due to hereditary syndromes comprises approximately 5% of the overall colorectal cancer burden. Conditions fall into two distinct categories, the polyposis syndromes and hereditary non-polyposis colorectal cancer. It is important for the clinician to have a working knowledge of both as screening and surveillance recommendations differ significantly from those applicable to the general population. The polyposis syndromes include familial adenomatous polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. For each condition, a review of both the intestinal and extra-intestinal clinical findings is presented as well as the genetic basis, genetic testing, screening, surveillance and treatment options. As genetic testing for several of these conditions has recently become both commercially available and standard practice, special attention is given to indications and strategies for genetic testing in hereditary colorectal cancer syndromes.

Overexpression of cyclooxygenase 2 in hamartomatous polyps of Peutz-Jeghers syndrome

OBJECTIVE

Peutz-Jeghers syndrome (PJS) is an autosomal-dominant hamartomatous polyposis syndrome. Affected individuals are at risk for intestinal and extraintestinal malignancies. Prostaglandins and polyamines are small molecules believed to be important in tumor formation and growth. Cyclooxygenase (COX) and ornithine decarboxylase (ODC) are key enzymes in the prostaglandin and polyamine biosynthetic pathways, respectively. The aim of this study was to measure and compare COX-1 and COX-2 expression in normal and hamartomatous tissue of PJS patients.

METHODS

We measured COX-1 and COX-2 protein expression in normal and hamartomatous GI tissues from affected PJS individuals and compared it with that in normal controls. COX-2 RNA in these tissues was also measured and compared by reverse transcription polymerase chain reaction (PCR). In addition, COX-2 expression was detected in tissue slides by immunostaining. ODC activity was measured between normal and hamartomatous tissues of PJS compared with control tissues.

RESULTS

COX-1 expression was similar in normal and control GI tissues. In contrast, COX-2 overexpression was noted in hamartomatous polyp tissue from PJS patients compared with normal control and PJS tissue. COX-2 expression by reverse transcription PCR was 10-fold greater in a hamartoma compared with other tissues. COX-2 expression was noted in the epithelial cells of hamartomatous polyps, and also coursing throughout the stromal tissue of the lamina propria, including muscle cells. ODC activity was similar in the tissues studied.

CONCLUSIONS

Selective COX-2 overexpression was noted in hamartomatous polyp tissue from PJS individuals. The results of the study provide an avenue for possible effective chemoprevention of polyp formation and growth in PJS.

Pancreatic cancer biology and genetics

Pancreatic ductal adenocarcinoma is an aggressive and devastating disease, which is characterized by invasiveness, rapid progression and profound resistance to treatment. Advances in pathological classification and cancer genetics have improved our descriptive understanding of this disease; however, important aspects of pancreatic cancer biology remain poorly understood. What is the pathogenic role of specific gene mutations? What is the cell of origin? And how does the stroma contribute to tumorigenesis? A better understanding of pancreatic cancer biology should lead the way to more effective treatments.

Heritable colorectal cancer syndromes: recognition and preventive management

Familial CRC syndromes account for a small yet important portion of colorectal malignancies. HNPCC, FAP, JPS, and Peutz-Jeghers syndrome are the four major conditions to r to consider if an hereditary condition is suspected in an individual with CRC. A multidisciplinary team comprised of a medical geneticist, gastroenterologist, pathologist, radiologist, and colorectal surgeon with expertise in recognizing and establishing the diagnosis of a specific familial cancer condition is crucial to implementing the proper management and prevention strategies unique to each of these syndromes. Genetic testing for each of these coniditions is available and useful for presymptomatic diagnosis and for indicated surveillance regimens. Vigilant endoscopic surveillance and careful timing of surgery are the mainstays of prevention for gastrointestinal malignancies. But with the advancement of genetic evaluation, improved cancer surveillance for intestinal as well as extraintestinal cancer, and chemopreventive strategies, the management of patients with a familial CRC syndrome will continue to evolve and, hopefully, significantly reduce their cancer burden.

Mutation analysis of the STK11/LKB1 gene and clinical characteristics of an Australian series of Peutz-Jeghers syndrome patients

Peutz-Jeghers syndrome (PJS) is a rare cancer predisposition, which is characterized by the presence of hamartomatous polyposis and mucocutaneous pigmentation. A significant proportion of both familial and sporadic forms of this disorder are associated with mutations in the STK11 (serine/threonine kinase 11)/LKB1 gene. In this report we present a series of Australian PJS cases, which suggest that mutations in the STK11 gene do not account for many families or patients without a family history. The most likely explanation is either the presence of another susceptibility gene or genetic mosaicism in the non-familial patients.

Ovarian tumors associated with multiple endocrine neoplasias and related syndromes (Carney complex, Peutz-Jeghers syndrome, von Hippel-Lindau disease, Cowden's disease)

Despite the relatively high prevalence of ovarian cancer (1% of American women will develop this disease in their lifetime) and recent developments in its molecular genetic understanding (several proto-oncogenes, such as AKT2 and cKRAS, and tumor suppressor genes, such as BRCA1 and BRCA2, have been implicated), little is known about the presence of ovarian tumors and cancer in women already diagnosed with other familial multiple tumor syndromes. In this review, we focus on the possible association of ovarian tumors with multiple endocrine neoplasias (MENs) and their related syndromes, such as Carney complex (CNC), Peutz-Jeghers syndrome (PJS), von Hippel-Lindau disease (VHLD), and Cowden's disease (CD). These conditions recently have been molecularly elucidated, and some of the genes responsible for them (including STK11/LKB1 and PTEN, the genes responsible for PJS and CD, respectively) have already been investigated in series of sporadic ovarian lesions, mostly carcinomas. A brief description of each disease is followed by a literature search for affected patients with ovarian tumors; we review our own experience with CNC patients and ovarian tumors. An association between PJS and CNC and ovarian neoplasms seems likely; carcinoids of the ovary may occur in patients with MEN 1. Only few patients with CD and VHLD have any ovarian pathology, but PTEN, the CD gene has been investigated in sporadic ovarian tumors. The aim of the present report is to alert clinicians who care for patients with MENs, CNC, PJS, VHLD, CD, and other syndromes for possible associations between various types of ovarian tumors and these conditions.

Genetics of Peutz-Jeghers syndrome, Carney complex and other familial lentiginoses

Peutz-Jeghers syndrome (PJS, #175200) and Carney complex (CNC, OMIM#160980) are the two most common multiple neoplasia syndromes associated with lentiginosis. Both disorders are inherited in an autosomal dominant manner and they have recently been elucidated at the molecular level. PJS and CNC share manifestations with Cowden syndrome (or Cowden disease) (CS, OMIM#158350) and Bannayan-Riley-Ruvalcaba syndrome (BRR, OMIM#153480). The endocrine tumors of CS and PJS, which could classify these disorders as variant types of multiple endocrine neoplasias (MENs), are not present in most CS and BRR patients, but lentigines are shared by PJS, CNC and BRR. The serine-threonine kinase STK11 (or LKB1), located on 19p13, is mutated in more than half of all PJS kindreds. The R1alpha subunit of c-AMP-dependent protein kinase A, located on 17q22-24, is mutated in 40% of CNC kindreds. The protein phosphatase PTEN is mutated in most cases of CS and in almost 50% of BRR kindreds, despite significant clinical heterogeneity in these syndromes. The molecular elucidation of the lentiginoses and their related syndromes identifies new pathways of growth control and cellular regulation that are important for endocrine signaling, tumorigenesis, cutaneous function and embryonic development.

Mutation screening at the RNA level of the STK11/LKB1 gene in Peutz-Jeghers syndrome reveals complex splicing abnormalities and a novel mRNA isoform (STK11 c.597(insertion mark)598insIVS4)

This study was intended to evaluate a diagnostic reverse transcriptase polymerase chain reaction based protein-truncation test for the identification of germline mutations in the serine/threonine protein kinase 11 (STK11, also designated LKB1) gene in Peutz-Jeghers syndrome (PJS). Our data exemplify that the inactivation of STK11 can be due to unusual disturbances in splicing regulation which result in truncations of the protein. However, nonsense mediated mRNA decay must be blocked with puromycin to detect shortened STK11 gene products contained in the leucocytic mRNA pool of PJS patients. Interestingly, two mutations escaped from detection by exon sequencing techniques with usual flanking PCR primers, since alterations were located right in the middle of intronic sequences. We describe a compound heterozygous PJS patient who carried two different mutations in intron 1 on separate alleles. Each of the two mutations was transmitted individually to one of his two children. In the course of our RNA based analyses we detected high level expression of a novel STK11/LKB1 mRNA variant retaining intron 4 (STK11 c.597(insertion mark)598insIVS4) in various tissues. This mRNA isoform was initiated from an alternative transcription regulatory region as revealed by primer extension analyses even in cell lines with complete methylation of the normal promoter. As a consequence of novel mutational mechanisms identified we discuss the impact of RNA based strategies for the detection of germinal STK11 mutations in PJS.

Inhibin and p27 interact to regulate gonadal tumorigenesis

Tumor suppressors function as antiproliferative signaling proteins, and defects in these genes lead to uncontrolled cell proliferation and cancer. For example, absence of the tumor suppressor p27(Kip1), a cyclin-dependent kinase inhibitor (CKI), results in increased body size, hyperplasia of several organs including the testes, and cancer in mice. Similarly, lack of inhibins, alpha/beta heterodimeric members of the transforming growth factor-beta (TGFbeta) superfamily, causes testicular and ovarian tumors of the granulosa/Sertoli cell lineage beginning at 4 weeks of age and adrenal tumors in gonadectomized mice. Neither the cell cycle alterations in the absence of inhibin nor the cause of the increased testis size in the p27 knockout mice is known. To study the molecular (cell cycle) changes that result from absence of inhibins, we analyzed the regulation of cell cycle proteins in gonadal tumors derived from inhibin alpha knockout mice (Inha(-/-)). Northern blot analyses demonstrate that cyclin-dependent kinase 4 (Cdk4) and cyclin D2 mRNA levels are elevated, and immunohistochemistry shows that p27 protein levels are decreased in both ovarian and testicular tumors from Inha(-/-) mice. These findings suggest that increased Cdk4/cyclin D2 (positive) activity and decreased p27 (negative) activity is causal for gonadal tumor formation. To test this hypothesis, we generated double mutant mice lacking both p27 and inhibin alpha to determine whether the tumor suppressors p27 and inhibin have additive suppressor activity in the gonads. Like Inha(-/-) mice, p27(-/-)Inha(-/-) mice demonstrate elevated serum activin levels, ovarian and testicular tumors, and a resultant lethal cachexia-like syndrome. However, whereas 95% of the Inha(-/-) female mice die by 18 weeks of age, 100% of the p27(-/-)Inha(-/-) female mice are dead by 8 weeks. Similarly, 95% of the Inha(-/-) single mutant males die by 13 weeks while 100% of the p27(-/-)Inha(-/-) male mice die by 10 weeks. Moreover, tumor foci in p27(-/-)Inha(-/-) mice can be observed as early as 2 weeks of age in males and as early as 4 weeks in females. These findings demonstrate that absence of both inhibin and p27 in mice causes earlier development of ovarian and testicular tumors and earlier death compared with absence of inhibin alone.

Gene for the human transmembrane-type protein tyrosine phosphatase H (PTPRH): genomic structure, fine-mapping and its exclusion as a candidate for Peutz-Jeghers syndrome

Mutations in the serine/threonine kinase STK11 lead to Peutz-Jeghers syndrome (PJS) in a subset of affected individuals. Significant evidence for linkage to a second potential PJS disease locus on 19q13.4 has previously been described in one PJS family (PJS07). In the current study, we investigated this second locus for PJS gene candidates. We mapped the main candidate gene in this region, the gene for the transmembrane-type protein tyrosine phosphatase H (PTPRH), within 15 kb telomeric to the marker D19S880. We determined its genomic structure, and performed mutation analysis of all exons and the exon-intron junctions of the PTPRH gene in the PJS07 family. No disease causing mutation was identified in PTPRH in affected individuals, suggesting the existence of an as yet not identified gene on 19q13.4 as a second PJS gene.

The genetics of pancreatic adenocarcinoma: a roadmap for a mouse model

Pancreatic cancer is among the leading causes of cancer death. Although a genetic profile for pancreatic cancer is emerging, many biological aspects of this disease are poorly understood. Indeed, fundamental questions regarding progenitor cell lineages, host stromal milieu, and the role of specific genetic alterations in tumor progression remain unresolved. A mouse model engineered with signature mutations would provide a powerful ally in the study of pancreatic cancer biology and may guide improved prognostic assessment and treatment for the human disease. In this review, we discuss the molecular basis for normal pancreatic development and the genetics of human pancreatic adenocarcinoma in the hope of charting a course for the development of a faithful mouse model for this lethal cancer.

Clinical genetics of multiple endocrine neoplasias, Carney complex and related syndromes

The list of multiple endocrine neoplasias (MENs) that have been molecularly elucidated is growing with the most recent addition of Carney complex. MEN type 1 (MEN 1), which affects primarily the pituitary, pancreas, and parathyroid glands, is caused by mutations in the menin gene. MEN type 2 (MEN 2) syndromes, MEN 2A and MEN 2B that affect mainly the thyroid and parathyroid glands and the adrenal medulla, and familial medullary thyroid carcinoma (FMTC), are caused by mutations in the REToncogene. Finally, Carney complex, which affects the adrenal cortex, the pituitary and thyroid glands, and the gonads, is caused by mutations in the gene that codes for regulatory subunit type 1A of protein kinase A (PKA) (PRKAR1A) in at least half of the known patients. Molecular defects have also been identified in syndromes related to the MENs, like Peutz-Jeghers syndrome (PJS) (the STK11/LKB1 gene), and Cowden (CD; the PTEN gene) and von Hippel-Lindau disease (VHLD; the VHL gene). Although recognition of these syndromes at a young age generally improves prognosis, the need for molecular testing in the diagnostic evaluation of the MENs is less clear. This review presents the newest information on the clinical and molecular genetics of the MENs (MEN 1, MEN 2, and Carney complex), including recommendations for genetic screening, and discusses briefly the related syndromes PJS, CD and VHLD.

An improved high throughput heteroduplex mutation detection system for screening BRCA2 mutations-fluorescent mutation detection (F-MD)

We describe an improved, fast, automated method for screening large genes such as BRCA2 for germline genomic mutations. The method is based on heteroduplex analysis, and has been adapted for a high throughput application by combining the fluorescent technology of automated sequencers and robotic sample handling. This novel approach allows the entire BRCA2 gene to be screened with appropriate overlaps in four lanes of an ABI 377 gel. The method will detect all types of mutations, especially point mutations, more reliably and robustly than other commonly used conformational sensitive methods (e.g. CSGE). In addition we show that this approach, which relies on band shift detection, is able to detect single base substitutions that have hitherto only been detectable by direct sequencing methods.