The effect of a promoter polymorphism on the transcription of nitric oxide synthase 1 and its relevance to Parkinson's disease.

Transcriptional changes of the enzyme nitric oxide synthase I (NOS1) are believed to play a role in the development of many diseases. The gene for NOS1 has 12 alternative first exons (1A-1L). The 1F exon is one of the most highly utilized first exons in the brain and has a polymorphism ((TG)(m)TA(TG)(n)) located in its promoter region. The polymorphism's length has been suggested to affect NOS1 transcription and play a role in Parkinson's disease (PD); however, the actual influence of the polymorphism on NOS1 transcription has not been studied. To better characterize the links of the polymorphism with PD, a genotyping study was done comparing polymorphism length among 170 PD patients and 150 age-matched controls. The pattern of changes between the two group's allele frequencies shows statistical significance (P = 0.0359). The smallest polymorphism sizes are more predominant among PD patients than controls. To study the effects of this polymorphism on NOS1 gene transcription, reporter gene constructs were made by cloning the NOS1 1F promoter with polymorphism lengths of either 42, 54, or 62 bp in front of the luciferase gene and transfecting them into HeLa or Sk-N-MC cells. NOS1-directed reporter gene constructs with the 62-bp polymorphism increased transcription of luciferase 2.2-fold in HeLa and 1.8-fold in Sk-N-MC cells compared with reporter gene constructs with the 42-bp polymorphism. These data suggest that if smaller polymorphism size contributes to the higher NOS1 levels in PD patients, an as yet unknown transcriptional mechanism is required.

Navajo neurohepatopathy is caused by a mutation in the MPV17 gene.

Navajo neurohepatopathy (NNH) is an autosomal recessive disease that is prevalent among Navajo children in the southwestern United States. The major clinical features are hepatopathy, peripheral neuropathy, corneal anesthesia and scarring, acral mutilation, cerebral leukoencephalopathy, failure to thrive, and recurrent metabolic acidosis with intercurrent infections. Infantile, childhood, and classic forms of NNH have been described. Mitochondrial DNA (mtDNA) depletion was detected in the livers of two patients, suggesting a primary defect in mtDNA maintenance. Homozygosity mapping of two families with NNH suggested linkage to chromosome 2p24. This locus includes the MPV17 gene, which, when mutated, causes a hepatocerebral form of mtDNA depletion. Sequencing of the MPV17 gene in six patients with NNH from five families revealed the homozygous R50Q mutation described elsewhere. Identification of a single missense mutation in patients with NNH confirms that the disease is probably due to a founder effect and extends the phenotypic spectrum associated with MPV17 mutations.

Pharmacogenetics--the horizon.

Pharmacogenetics is a growing discipline with great potential for improving human health care. This article provides a broad overview of the field to set the stage for discussions elsewhere in this publication of pharmacogenetic applications for treatment of inflammatory bowel disease. Pharmacogenetics is defined and positioned appropriately in the large picture of drug response and failure. A vision for pharmacogenetic applications and optimal pharmacogenetic candidates is discussed. Two examples of compounds that have failed at least partly because of pharmacogenetic considerations are discussed. Finally, some predictions are presented regarding large-scale clinical applications and current hindrances to those applications.