Impact of KRAS and TP53 mutations on survival in patients with left- and right-sided Dukes' C colon cancer.

Objective: It has been suggested that KRAS and TP53 mutated tumors might influence the phenotypic behavior of left- and right-sided colon tumors. We investigated the incidence of these mutations in left- and right-sided colon tumors and their possible influence on survival in a homogeneous group of patients with Dukes' C colon cancers.

Methods: The primary tumors of 55 patients with a sporadic Dukes' C colon cancer, all treated with adjuvant chemotherapy were analyzed for the presence of KRAS and TP53 mutations.

A single-nucleotide polymorphic variant of the RET proto-oncogene is underrepresented in sporadic Hirschsprung disease.

Hirschsprung disease (HSCR) is an inherited disorder characterised by absence of intrinsic ganglion cells in the distal gastrointestinal tract. Different susceptibility genes, involved in either the Ret-tyrosine kinase or the endothelin signalling pathways, contribute to HSCR phenotype. Interestingly, alterations of these genes are detected in only 30-50% of all HSCR patients, suggesting the involvement of modifier genes and/or additional genetic or environmental risk factors.

A consanguineous family with Hirschsprung disease, microcephaly, and mental retardation (Goldberg-Shprintzen syndrome).

Hirschsprung disease, mental retardation, microcephaly, and specific craniofacial dysmorphism were observed in three children from a large, consanguineous, Moroccan family. A fourth child showed similar clinical features, with the exception of Hirschsprung disease. The association of these abnormalities in these children represents the Goldberg-Shprintzen syndrome (OMIM 235730).

Novel missense mutation in the L1 gene in a child with corpus callosum agenesis, retardation, adducted thumbs, spastic paraparesis, and hydrocephalus.

Corpus callosum agenesis, retardation, adducted thumbs, spastic paraparesis, and hydrocephalus (CRASH syndrome) is an X-linked recessive disorder caused by mutations in the neuronal cell adhesion molecule L1 (LICAM) gene. L1 plays a key role in axon outgrowth and pathfinding during the development of the nervous system. We describe the case of a boy from the United Arab Emirates who presented with CRASH syndrome.

Reduced endothelin-3 expression in sporadic Hirschsprung disease.

Background: Enteric aganglionosis in Hirschsprung disease has been linked to genes coding for endothelin-3 (EDN3) and the endothelin B receptor (EDNRB), but there is no such linkage in most patients with sporadic Hirschsprung disease. However, the similarity between the distal colonic aganglionosis in Hirschsprung disease and that due to EDN3 or EDNRB mutations led to the hypothesis that levels of expression of these genes might be affected in the absence of mutation, thus causing the Hirschsprung disease phenotype. The aim of this study was to determine EDN3 and EDNRB messenger RNA (mRNA) levels in tissue samples from patients with sporadic Hirschsprung disease.

RET and GDNF gene scanning in Hirschsprung patients using two dual denaturing gel systems.

Hirschsprung disease (HSCR) is a congenital disorder characterised by intestinal obstruction due to an absence of intramural ganglia along variable lengths of the intestine. RET is the major gene involved in HSCR. Mutations in the GDNF gene, and encoding one of the RET ligands, either alone or in combination with RET mutations, can also cause HSCR, as can mutations in four other genes (EDN3, EDNRB, ECE1, and SOX10).

Incidence of RET mutations in patients with Hirschsprung's disease.

Background: RET mutations have been reported variously to affect 7% to 41% of Hirschsprung's disease (HSCR) patients depending on familial or sporadic occurrence of the disease, length of aganglionosis and possible association with other disease phenotypes. The authors report a study of the incidence of RET mutations in unselected HSCR patients from two regional centers and correlate their genotypes and phenotypes.

Methods: The records of HSCR patients treated in 2 regional centers with a combined population of 5 million were reviewed, and blood samples were obtained from 57 patients.

Mutational analyses of BRCA1 and BRCA2 in Ashkenazi and non-Ashkenazi Jewish women with familial breast and ovarian cancer.

In Ashkenazi (East European) Jews, three predominant mutations in BRCA1 (185delAG and 5382insC) and BRCA2 (6174delT) account for the majority of germline mutations in high-risk breast and/or ovarian cancer families. Among non-Ashkenazi Jews, the 185delAG, Tyr978Ter, and a handful of "private" mutations have been reported anecdotally within both genes. In this study we attempted to determine the spectrum of BRCA1 and BRCA2 mutations in high-risk Jewish individuals, non-carriers of any of the predominant Jewish mutations.

A human model for multigenic inheritance: phenotypic expression in Hirschsprung disease requires both the RET gene and a new 9q31 locus.

Reduced penetrance in genetic disorders may be either dependent or independent of the genetic background of gene carriers. Hirschsprung disease (HSCR) demonstrates a complex pattern of inheritance with approximately 50% of familial cases being heterozygous for mutations in the receptor tyrosine kinase RET. Even when identified, the penetrance of RET mutations is only 50-70%, gender-dependent, and varies with the extent of aganglionosis.

Maternal uniparental disomy for chromosome 14 in a boy with a normal karyotype.

We report on a boy with a maternal uniparental disomy for chromosome 14 (UPD(14)). At 7 years of age he was referred to us by the paediatrician because of symptoms of Prader-Willi syndrome (PWS). He showed short stature, obesity, mild developmental delay, cryptorchidism, and some mild dysmorphic features.

Association of hereditary nonpolyposis colorectal cancer-related tumors displaying low microsatellite instability with MSH6 germline mutations.

Hereditary nonpolyposis colorectal cancer (HNPCC) (Amsterdam criteria) is often caused by mutations in mismatch repair (MMR) genes, and tumors of patients with HNPCC show microsatellite instability (MSI-high phenotype). Germline mutations of MMR genes have rarely been found in families that have HNPCC or suspected HNPCC and that do not show microsatellite instability (MSI-low phenotype). Therefore, an MSI-high phenotype is often used as an inclusion criterion for mutation testing of MMR genes.

Improvements in gel composition and electrophoretic conditions for broad-range mutation analysis by denaturing gradient gel electrophoresis.

Denaturing gradient gel electrophoresis (DGGE) is believed to be the most powerful pre-screening method for mutation detection currently available, being used mostly on an exon-by-exon basis. Broad-range DGGE for the analysis of multiple fragments or an entire gene is rarely applied. We and others have already shown that one or two DGGE conditions are usually sufficient to analyse an entire gene.

Two distinct mutations of the RET receptor causing Hirschsprung's disease impair the binding of signalling effectors to a multifunctional docking site.

The RET gene codes for a transmembrane tyrosine kinase which is a subunit of a multimeric complex that acts as a receptor for four structurally related molecules: the glial cell line-derived neurotrophic factor (GDNF), neurturin, artemin and persephin. Germline mutations of RET cause a dominantly inherited dysgenesis of the enteric nervous system known as Hirschsprung's disease (HSCR; aganglionosis megacolon). The majority of HSCR mutations results either in a reduction of dosage of the RET protein or in the loss of RET function.

Improved mutation detection in GC-rich DNA fragments by combined DGGE and CDGE.

Denaturing gradient gel electrophoresis (DGGE) has proven to be a powerful pre-screening method for the detection of DNA variants. If such variants occur, however, in DNA fragments that are very rich in G and C, they may escape detection. To overcome this limitation, we tested a novel gel system which combines DGGE and constant denaturant gel electrophoresis (CDGE), as it might have the advantages of both methods.

Tetrasomy 9p due to an intrachromosomal triplication of 9p13-p22.

To date, approximately 30 patients have been described with a tetrasomy 9p, all being caused by the presence of an isochromosome 9p. We now report on a 3-year-old boy with a de novo intrachromosomal triplication of 9p13-p22, resulting in partial tetrasomy 9p. We compared his phenotype with cases of tetrasomy 9p caused by the presence of an extra isochromosome 9p.

High frequency of TP53 mutations in juvenile pilocytic astrocytomas indicates role of TP53 in the development of these tumors.

In adults, the TP53 tumor suppressor gene is frequently mutated in astrocytic brain tumors which is supposed to represent an early event in their development. In juvenile pilocytic and low-grade astrocytomas, however, TP53 mutations have until now been reported as rare, which has led to the suggestion that these tumors may follow a different molecular pathogenesis with an involvement of genes other than TP53. Our analysis of 20 pilocytic and two low-grade astrocytomas of childhood, based on a comprehensive denaturing gradient gel electrophoresis (DGGE) mutation detection assay of the entire coding region, including all splice site junctions of TP53, showed mutations considered as causative in 7 of the 20 (35%) pilocytic astrocytomas and in one of the two low-grade astrocytomas.

[Genes and genetics in Hirschsprung's disease].

Hirschsprung's disease (HSCR) is a congenital disorder characterized by intestinal obstruction due to the absence of intramural ganglia along variable lengths of the colon. Occurrence among family members and recurrence risks among siblings are indications for involvement of genetic predispositions. Mutations have been discovered in five different susceptibility genes.

Comprehensive TP53-denaturing gradient gel electrophoresis mutation detection assay also applicable to archival paraffin-embedded tissue.

A comprehensive mutation detection assay is described for the entire coding region and all splice site junctions of TP53. The assay is based on denaturing gradient gel electrophoresis, which follows either multiplex polymerase chain reaction (PCR) applied to DNA extracted from fresh or frozen tissue samples or nested PCR applied to DNA extracted from paraffin-embedded tissue samples. In both instances, the analysis can be performed under a single set of conditions.

A Hirschsprung disease locus at 22q11?

We report a boy with truncus arteriosus, dysmorphic features, developmental delay, passing hypotonia, short segment Hirschsprung disease (HSCR), and paroxysmal hypoventilation. FISH analysis showed an interstitial deletion in chromosome band 22q11.2 coinciding with the deletions found in DiGeorge syndrome and velocardiofacial syndrome.

Improvement of fragment and primer selection for mutation detection by denaturing gradient gel electrophoresis.

Denaturing gradient gel electrophoresis (DGGE) is one of the most powerful methods for mutation detection currently available. For successful application the appropriate selection of PCR fragments and PCR primers is crucial. The sequence of interest should always be within the domain with the lowest melting temperature.

Oncological implications of RET gene mutations in Hirschsprung's disease.

Background: Germline mutations of the RET proto-oncogene identical to those found in the tumour predisposition syndrome multiple endocrine neoplasia type 2A (MEN2A), were detected in 2.5-5% of sporadic and familial cases of Hirschsprung's disease. Some patients with Hirschsprung's disease may therefore be exposed to a highly increased risk of tumours.