Mutations in PTF1A cause pancreatic and cerebellar agenesis.

Individuals with permanent neonatal diabetes mellitus usually present within the first three months of life and require insulin treatment. We recently identified a locus on chromosome 10p13-p12.1 involved in permanent neonatal diabetes mellitus associated with pancreatic and cerebellar agenesis in a genome-wide linkage search of a consanguineous Pakistani family. Here we report the further linkage analysis of this family and a second family of Northern European descent segregating an identical phenotype. Positional cloning identified the mutations 705insG and C886T in the gene PTF1A, encoding pancreas transcription factor 1alpha, as disease-causing sequence changes. Both mutations cause truncation of the expressed PTF1A protein C-terminal to the basic-helix-loop-helix domain. Reporter-gene studies using a minimal PTF1A deletion mutant indicate that the deleted region defines a new domain that is crucial for the function of this protein. PTF1A is known to have a role in mammalian pancreatic development, and the clinical phenotype of the affected individuals implicated the protein as a key regulator of cerebellar neurogenesis. The essential role of PTF1A in normal cerebellar development was confirmed by detailed neuropathological analysis of Ptf1a(-/-) mice.

An adenosine nucleoside inhibitor of dengue virus.

Dengue virus (DENV), a mosquito-borne flavivirus, is a major public health threat. The virus poses risk to 2.5 billion people worldwide and causes 50 to 100 million human infections each year. Neither a vaccine nor an antiviral therapy is currently available for prevention and treatment of DENV infection. Here, we report a previously undescribed adenosine analog, NITD008, that potently inhibits DENV both in vitro and in vivo. In addition to the 4 serotypes of DENV, NITD008 inhibits other flaviviruses, including West Nile virus, yellow fever virus, and Powassan virus. The compound also suppresses hepatitis C virus, but it does not inhibit nonflaviviruses, such as Western equine encephalitis virus and vesicular stomatitis virus. A triphosphate form of NITD008 directly inhibits the RNA-dependent RNA polymerase activity of DENV, indicating that the compound functions as a chain terminator during viral RNA synthesis. NITD008 has good in vivo pharmacokinetic properties and is biologically available through oral administration. Treatment of DENV-infected mice with NITD008 suppressed peak viremia, reduced cytokine elevation, and completely prevented the infected mice from death. No observed adverse effect level (NOAEL) was achieved when rats were orally dosed with NITD008 at 50 mg/kg daily for 1 week. However, NOAEL could not be accomplished when rats and dogs were dosed daily for 2 weeks. Nevertheless, our results have proved the concept that a nucleoside inhibitor could be developed for potential treatment of flavivirus infections.

Agricultural pesticide residues of farm runoff in the Okanagan Valley, British Columbia, Canada.

The objectives of this study were to determine environmental occurrence and concentrations of selected currently-used-pesticides and some transformation products in agricultural farms in the Okanagan Valley (OKV), and to conduct a simple risk assessment of environmental pesticides levels detected in OKV on non-target aquatic organisms. The OKV is the tree fruit country of the Province of British Columbia where considerable amount of pesticides are applied annually. Water, sediment and soil samples were collected at eleven sites in early June and late September following rainfall events and/or extended periods of irrigation from drainage ditches and/or from small streams. Undisturbed reference sites were also sampled. Study results showed that forty of the eighty chemicals analyzed, including organochlorine, nitrogen-containing and organophosphate pesticides commonly used for OKV crops, were detected in runoff and small stream water samples. Among which, endosulfan-sulfate was the most frequently detected chemical. Also, azinophos-methyl (0.699-25.5 ng/L), diazinon (0.088-214 ng/L) exceeded, and α-, ß- endosulfan, endosulfan sulphate approached the guidelines for the protection of aquatic life.

Genomewide linkage searches for Mendelian disease loci can be efficiently conducted using high-density SNP genotyping arrays.

Genomewide linkage searches aimed at identifying disease susceptibility loci are generally conducted using 300-400 microsatellite markers. Genotyping bi-allelic single nucleotide polymorphisms (SNPs) provides an alternative strategy. The availability of dense SNP maps coupled with recent technological developments in highly paralleled SNP genotyping makes it practical to now consider the use of these markers for whole-genome genetic linkage analyses. Here, we report the findings from three successful genomewide linkage analyses of families segregating autosomal recessively inherited neonatal diabetes, craniosynostosis and dominantly inherited renal dysplasia using the Affymetrix 10K SNP array. A single locus was identified for each disease state, two of which are novel. The performance of the SNP array, both in terms of efficiency and precision, indicates that such platforms will become the dominant technology for performing genomewide linkage searches.

A novel gene for neonatal diabetes maps to chromosome 10p12.1-p13.

We report a genomewide linkage analysis of a large consanguineous family segregating autosomal recessively inherited neonatal diabetes and the identification of a novel neonatal diabetes locus. Neonatal diabetes was characterized by low levels of circulating C-peptide with very low to undetectable levels of insulin in the presence of severe hyperglycemia unresponsive to insulin infusion. A dense genomewide linkage search of the family was undertaken using a first generation 10K single nucleotide polymorphism chip containing 10,044 markers. A region of homozygosity harboring the neonatal diabetes disease gene on chromosome 10p12.1-p13 was identified (multipoint logarithm of odds score 3.25). There is a strong history of type 2 diabetes in carriers of the disease gene. It is likely that chromosome 10p12.1-p13 may harbor a maturity-onset diabetes of the young or type 2 diabetes gene.

Human piebaldism: six novel mutations of the proto-oncogene KIT.

Human piebaldism is a rare autosomal dominant disorder that comprises congenital patchy depigmentation of the scalp, forehead, trunk and limbs. It is caused by mutations in the cell-surface receptor tyrosine kinase gene (KIT, also c-kit). We screened three families and three isolated cases of piebaldism from different countries for mutations in the KIT gene using automated sequencing methods. We report six novel KIT point mutations: three missense (C788R, W835R, P869S) at highly conserved amino acid sites; one nonsense (Q347X) that results in termination of translation of the KIT gene in exon 6; and two splice site nucleotide substitutions (IVS13+2T>G, IVS17-1G>A) that are predicted to impair normal splicing. These mutations were not detected in over 100 normal individuals and are likely to be the cause of piebaldism in our subjects.

Benign metastasizing leiomyomatosis: case report and review.

The authors report an interesting case of a minimally symptomatic 23-year-old African American woman who was found to have extensive diffuse reticulonodular opacities of the lungs on a routine chest radiograph. She had a hysterectomy 5 years previously for multiple leiomyomas of the uterus. She had no history of any prior exposure to dusts or toxins. Collagen vasculitides and bacterial, mycobacterial, and fungal infectious causes were excluded through standard testing, and a bronchoscopic lung biopsy was nonspecific. An open lung biopsy revealed multiple nodules of proliferating smooth muscle cells intermixed with irregular areas of epithelial-lined spaces. Histologically, the muscle cells appear benign with a very low mitotic rate, and the pathologic findings were consistent with benign metastasizing leiomyomatosis (BML). Staining for estrogen and progesterone receptors, actin, and c-kit were performed. This case and the review of the medical literature support the concept that BML originates from an antecedent leiomyoma of the uterus in virtually all cases with rare exceptions. It appears that tumor metastasizes to lungs or other extrauterine tissues via hematogenous spread. However, the origin of the tumor remains controversial. BML is a rare entity, with only a handful of reports in the medical literature. The authors report an interesting case of BML in a 23-year-old patient who, to their knowledge, is the youngest such patient described and who, at 13 years, has the longest period of clinical follow-up. In this article, the authors review the pathogenesis, cytogenetics, histologic markers, and management options of this rare entity.