Mutations in a novel serine protease PRSS56 in families with nanophthalmos.

Purpose: Nanophthalmos is a rare genetic ocular disorder in which the eyes of affected individuals are abnormally small. Patients suffer from severe hyperopia as a result of their markedly reduced axial lengths, but otherwise are capable of seeing well unlike other more general forms of microphthalmia. To date one gene for nanophthalmos has been identified, encoding the membrane-type frizzled related protein MFRP.

The role of Frizzled-4 mutations in familial exudative vitreoretinopathy and Coats disease.

Aim: The aim of this study is to assess the role of Frizzled-4 (FZD4) in familial exudative vitreoretinopathy (FEVR) and Coats disease.

Methods: Tissue samples were collected for DNA extraction and automated DNA sequencing of the two coding exons of FZD4 in both directions. Cases carrying a FZD4 mutation and demonstrating extreme disease severity were selected for direct automated sequencing of all coding exons of LRP5, NDP and TSPAN12.

Mutation in the gene encoding ubiquitin ligase LRSAM1 in patients with Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease (CMT) represents a family of related sensorimotor neuropathies. We studied a large family from a rural eastern Canadian community, with multiple individuals suffering from a condition clinically most similar to autosomal recessive axonal CMT, or AR-CMT2. Homozygosity mapping with high-density SNP genotyping of six affected individuals from the family excluded 23 known genes for various subtypes of CMT and instead identified a single homozygous region on chromosome 9, at 122,423,730-129,841,977 Mbp, shared identical by state in all six affected individuals.

Mutations in centrosomal protein CEP152 in primary microcephaly families linked to MCPH4.

Primary microcephaly is a rare condition in which brain size is substantially diminished without other syndromic abnormalities. Seven autosomal loci have been genetically mapped, and the underlying causal genes have been identified for MCPH1, MCPH3, MCPH5, MCPH6, and MCPH7 but not for MCPH2 or MCPH4. The known genes play roles in mitosis and cell division.

Severe retinopathy of prematurity associated with FZD4 mutations.

Purpose: To determine whether mutations in the FZD4 gene are a risk factor for developing severe ROP.

Methods: Three Canadian tertiary care centers recruited premature infants prospectively and retrospectively, and assigned affectation status based on the maximum degree of severity of ROP recorded in both eyes. Mutation screening of the FZD4 gene was performed using direct sequencing.

A polymorphic variant of the insulin-like growth factor type I receptor gene modifies risk of obesity for esophageal adenocarcinoma.

Background: To investigate potential biologic mechanisms underlying the association between obesity and risk for esophageal adenocarcinoma (EADC), we studied the frequency of a common polymorphism of the insulin-like growth factor I receptor (IGF-IR) gene in patients with either gastroesophageal reflux disease (GERD), premalignant Barrett esophagus (BE) and or invasive EADC.

Methods: Using a well characterized series of 431 individuals enrolled in a case-control study, we studied the frequency of the IGF-IR gene polymorphism, G1013A.

Results: On multivariate analysis controlling for age and gender, in comparison to asymptomatic controls, obese individuals with the polymorphic A-variant (G/A, A/A) were found to have significantly increased risk for EADC (OR 4.

Mutation in pyrroline-5-carboxylate reductase 1 gene in families with cutis laxa type 2.

Autosomal-recessive cutis laxa type 2 (ARCL2) is a multisystem disorder characterized by the appearance of premature aging, wrinkled and lax skin, joint laxity, and a general developmental delay. Cutis laxa includes a family of clinically overlapping conditions with confusing nomenclature, generally requiring molecular analyses for definitive diagnosis. Six genes are currently known to mutate to yield one of these related conditions.

Regulation of CDX2 expression in esophageal adenocarcinoma.

Reflux of acidic gastric contents and bile acids into the lower esophagus has been identified to have a central role in esophageal malignancy and is reported to upregulate caudal-related homologue 2 (CDX2), a regulatory gene involved in embryonic development and axial patterning of the alimentary tract. The aim of this study was to characterize the expression of CDX2 in a well-defined series of human esophageal tissues, comprising reflux-induced esophagitis, premalignant Barrett esophagus (BE), and primary esophageal adenocarcinoma (EADC). To explore potential molecular regulatory mechanisms, we also studied the expression of beta-catenin, SOX9, and CDX2 promoter methylation in esophageal tissues, in addition to the effect of bile acids and nitric oxide (NO) on CDX2 expression in the normal human esophageal cell line Het1A.

Mutations in mitochondrial carrier family gene SLC25A38 cause nonsyndromic autosomal recessive congenital sideroblastic anemia.

The sideroblastic anemias are a heterogeneous group of congenital and acquired hematological disorders whose morphological hallmark is the presence of ringed sideroblasts--bone marrow erythroid precursors containing pathologic iron deposits within mitochondria. Here, by positional cloning, we define a previously unknown form of autosomal recessive nonsyndromic congenital sideroblastic anemia, associated with mutations in the gene encoding the erythroid specific mitochondrial carrier family protein SLC25A38, and demonstrate that SLC25A38 is important for the biosynthesis of heme in eukaryotes.

Application of homozygosity haplotype analysis to genetic mapping with high-density SNP genotype data.

Background: In families segregating a monogenic genetic disorder with a single disease gene introduction, patients share a mutation-carrying chromosomal interval with identity-by-descent (IBD). Such a shared chromosomal interval or haplotype, surrounding the actual pathogenic mutation, is typically detected and defined by multipoint linkage and phased haplotype analysis using microsatellite or SNP genotype data. High-density SNP genotype data presents a computational challenge for conventional genetic analyses.

Phenotypic overlap of familial exudative vitreoretinopathy (FEVR) with persistent fetal vasculature (PFV) caused by FZD4 mutations in two distinct pedigrees.

Purpose: To describe a severe familial exudative vitreoretinopathy (FEVR) phenotype seen in infancy that resembles persistent fetal vasculature (PFV) caused by mutations in the FZD4 gene in two pedigrees with high intrafamilial variability.

Methods: Three infants presented with features compatible with bilateral PFV. Eye examinations from the affected children and their relatives were reviewed retrospectively (follow-up:18 months-9 years).

Is gene discovery research or diagnosis?

The criteria that distinguish human genetic research from clinical molecular diagnosis are frequently practical rather than theoretical. They are driven by the availability and costs of the relevant technologies and the systemic level of scientific fluency in interpreting laboratory results. The guiding principle in the practice of medicine is the primacy of patient care.

Inducible nitric oxide synthase, nitrotyrosine and p53 mutations in the molecular pathogenesis of Barrett's esophagus and esophageal adenocarcinoma.

Nitric oxide (NO) has been implicated as a potential causative factor for endogenous p53 mutations in gastrointestinal malignancy. To investigate the role of NO in esophageal adenocarcinoma (EADC), we studied patterns of p53 mutations, expression of inducible nitric oxide synthase (iNOS) and the tissue accumulation of nitrotyrosine (NTS), a stable reaction product of NO and a marker for cellular protein damage, in human premalignant and malignant esophageal epithelia. Tissues were obtained from patients with gastroesophageal reflux disease (GERD)-induced esophagitis (n = 76), Barrett's esophagus (BE; n = 119) and primary EADC (n = 54).

Stem cells, senescence, neosis and self-renewal in cancer.

We describe the basic tenets of the current concepts of cancer biology, and review the recent advances on the suppressor role of senescence in tumor growth and the breakdown of this barrier during the origin of tumor growth. Senescence phenotype can be induced by (1) telomere attrition-induced senescence at the end of the cellular mitotic life span (MLS*) and (2) also by replication history-independent, accelerated senescence due to inadvertent activation of oncogenes or by exposure of cells to genotoxins. Tumor suppressor genes p53/pRB/p16INK4A and related senescence checkpoints are involved in effecting the onset of senescence.

Current and future approaches for the therapeutic targeting of metastasis (review).

Metastasis is the process whereby cancer cells disseminate and establish secondary tumors at distant sites from the primary tumor and is estimated to be responsible for approximately 90% of all cancer deaths. Cancers with metastatic spread are frequently resistant to conventional chemotherapeutic approaches, underlining the urgent need for novel treatments in these diseases. Recent advances in understanding the mechanisms underlining both the intrinsic cellular and extrinsic micro-environmental factors contributing to the metastatic process have resulted in the identification of a number of molecular targets for the development of specific anti-metastatic therapeutic strategies.

Genetic polymorphisms of microsomal epoxide hydroxylase and glutathione S-transferases M1, T1 and P1, interactions with smoking, and risk for esophageal (Barrett) adenocarcinoma.

Background: The aim of this case-control study was to test the hypothesis that polymorphisms of the microsomal epoxide hydroxylase (mEH) and glutathione S-transferase (GST) genes modulate the susceptibility to esophageal adenocarcinoma (EADC) associated with smoking.

Methods: Cases included patients with gastroesophageal reflux disease (GERD) (n=126), Barrett esophagus (BE) (n=125), and EADC (n=56); controls comprised 95 strictly asymptomatic individuals. Genomic DNA was extracted from blood samples, and PCR-based assays were used to genotype mEH (slow allele, fast allele, predicted activity) and GSTM1, GSTT1 and GSTP1.

Epidemiology and molecular biology of Barrett esophagus.

Over the past three decades, there has been a marked change in the epidemiology of esophageal malignancy, with an increasing incidence of esophageal adenocarcinoma. The reasons for this are largely unknown and remain controversial, but several lifestyle risk factors have been proposed, including gastroesophageal reflux disease (GERD). It is hypothesized that chronic GERD results in acute mucosal injury, promotes cellular proliferation, and induces specialized columnar metaplasia (Barrett esophagus).

Neosis--a paradigm of self-renewal in cancer.

We recently described a novel form of cell division termed neosis, which appears to be the mode of escape of cells from senescence and is involved in the neoplastic transformation and progression of tumors (Cancer Biol & Therap 2004;3:207-18). Neosis is a parasexual somatic reduction division and is characterized by (1) DNA damage-induced senescence/mitotic crisis and polyploidization, (2) followed by production of aneuploid daughter cells via nuclear budding, (3) asymmetric cytokinesis and cellularization conferring extended, but, limited mitotic life span to the offspring, and (4) is repeated several times during tumor growth. The immediate neotic progeny are termed the Raju cells, which seem to transiently display stem cell properties.

Cyclin D1 polymorphism (G870A) and risk for esophageal adenocarcinoma.

Background: To investigate individual susceptibility to gastroesophageal reflux disease, Barrett esophagus, and esophageal adenocarcinoma, the authors studied the frequency of the common G870A polymorphism of CCND1, which encodes cyclin D1, a key cell cycle regulatory protein.

Methods: The study population included 307 patients who were enrolled in a prospective case-control study to evaluate lifestyle risk factors and molecular alterations in gastroesophageal reflux disease (n = 126 patients), Barrett esophagus (n = 125 patients), and esophageal adenocarcinoma (n = 56 patients). A control group included 95 strictly asymptomatic individuals.

Polymorphisms in DNA repair genes in the molecular pathogenesis of esophageal (Barrett) adenocarcinoma.

To test the hypothesis that aberrations of DNA repair contribute to susceptibility for the progression of gastroesophageal reflux disease (GERD) into Barrett esophagus (BE) and esophageal adenocarcinoma (EADC), we studied the frequency of polymorphisms of selected DNA repair genes in patients with GERD (n = 126), BE (n = 125) and EADC (n = 56) enrolled in a 2-year prospective case-control study. Controls comprised 95 strictly asymptomatic healthy individuals. Using genomic DNA extracted from blood samples, we identified wild-type and polymorphic variants of XPD (Arg156Arg and Lys751Gln), XRCC1 (Arg194Trp and Arg399Gln) and XRCC3 (Thr241Met), and the poly (AT) insertion/deletion of XPC (PAT).

Microsatellite instability in esophageal adenocarcinoma.

The frequency of microsatellite instability (MSI), a result of defective mismatch repair during DNA replication, has been reported inconsistently in primary esophageal adenocarcinoma (EADC). Using a panel of 15 markers, the primary aim of this study was to analyze the frequency of MSI in a well-characterized series of 27 primary EADCs, defined according to strict clinicopathologic criteria. Polymerase chain reaction was used to amplify the following microsatellite repeat loci: D2S123, D10S197, D2S119, D11S904, D2S147, D3S1764, D7S1830, D7S1805, D2S434, D9S299, BAT25, BAT26, D5S346, D17S250, and TGF-beta-RII.

Neosis: a novel type of cell division in cancer.

Using computerized video time-lapse microscopy, we studied early cellular events during carcinogen-induced transformation of C3H10T1/2 cells. Multinucleate/polyploid giant cells (MN/PGs) formed due to DNA damage are thought to die via mitotic catastrophe. Before they die, some MN/PGs undergo a novel type of cell division, termed neosis, characterized by karyokinesis via nuclear budding followed by asymmetric, intracellular cytokinesis, producing several small mononuclear cells, termed the Raju cells, with extended mitotic life span (MLS).

Clinical implications of p53 tumor suppressor gene mutation and protein expression in esophageal adenocarcinomas: results of a ten-year prospective study.

Objective: This study was undertaken to characterize the spectrum of p53 alterations (mutations and protein expression) in surgically resected esophageal adenocarcinomas, and to correlate molecular alterations with clinicopathologic findings and outcome.

Methods: Between 1991 and 2001, 91 consecutive patients with esophageal adenocarcinomas underwent subtotal esophagectomy. No patient received induction therapy.

ING1 and p53 tumor suppressor gene alterations in adenocarcinomas of the esophagogastric junction.

The aim of this study was to characterize molecular alterations of the recently reported candidate tumor suppressor gene, ING1, and to explore the relationship between ING1 and p53 in a well-defined series of adenocarcinomas of the esophagogastric junction (AdEGJ). Polymerase chain reaction (PCR)-based assays were used to characterize ING1 and p53 alterations, relative to histologically normal esophageal mucosa. Two tumors were found to have ING1 mutations: one novel missense mutation (AGC(Ser)-->ATC(Ile)) at codon 147, and one silent mutation (TCG(Ser)-->TCA(Ser)) at codon 173.