Variations in the promoter region of the glutaminase gene and the development of hepatic encephalopathy in patients with cirrhosis: a cohort study.

BACKGROUND: Hepatic encephalopathy is a major complication of cirrhosis and is associated with a poor prognosis. OBJECTIVE: To identify mutations in the gene sequence for glutaminase in humans that could be responsible for the development of hepatic encephalopathy in patients with cirrhosis. DESIGN: Cohort study. SETTING: Outpatient clinics in 6 Spanish hospitals. PATIENTS: 109 consecutive patients with cirrhosis in the estimation cohort, 177 patients in the validation cohort, and 107 healthy control participants. MEASUREMENTS: Patients were followed every 3 or 6 months until the development of hepatic encephalopathy or liver transplantation, death, or the end of the study. RESULTS: The genetic analyses showed that glutaminase TACC and CACC haplotypes were linked to the risk for overt hepatic encephalopathy. Mutation scanning of the glutaminase gene identified a section in the promoter region where base pairs were repeated (a microsatellite). Over a mean follow-up of 29.6 months, hepatic encephalopathy occurred in 28 patients (25.7%) in the estimation cohort. Multivariable Cox models were used to determine the following independent predictors: Child-Turcotte-Pugh stage (hazard ratio [HR], 1.6 [95% CI, 1.29 to 1.98]; P = 0.001), minimal hepatic encephalopathy (HR, 3.17 [CI, 1.42 to 7.09]; P = 0.006), and having 2 long alleles of the microsatellite (HR, 3.12 [CI, 1.39 to 7.02]; P = 0.006). The association between 2 long alleles of the microsatellite and overt hepatic encephalopathy was confirmed in a validation cohort (HR, 2.1 [CI, 1.17 to 3.79]; P = 0.012). Functional studies showed higher luciferase activity in cells transfected with the long form of the microsatellite, which suggests that the long microsatellite enhances glutaminase transcriptional activity. LIMITATION: Other genes and allelic variants might be involved in the clinical expression of hepatic encephalopathy. CONCLUSION: This study identifies a genetic factor that is associated with development of hepatic encephalopathy in patients with cirrhosis. PRIMARY FUNDING SOURCE: Instituto de Salud Carlos III, Spanish Ministry of Health.

Genetic structure of the Spanish population.

BACKGROUND: Genetic admixture is a common caveat for genetic association analysis. Therefore, it is important to characterize the genetic structure of the population under study to control for this kind of potential bias. RESULTS: In this study we have sampled over 800 unrelated individuals from the population of Spain, and have genotyped them with a genome-wide coverage. We have carried out linkage disequilibrium, haplotype, population structure and copy-number variation (CNV) analyses, and have compared these estimates of the Spanish population with existing data from similar efforts. CONCLUSIONS: In general, the Spanish population is similar to the Western and Northern Europeans, but has a more diverse haplotypic structure. Moreover, the Spanish population is also largely homogeneous within itself, although patterns of micro-structure may be able to predict locations of origin from distant regions. Finally, we also present the first characterization of a CNV map of the Spanish population. These results and original data are made available to the scientific community.

Human controlled ovarian hyperstimulation outcome is a polygenic trait.

This study aimed to evaluate the association between follicle-stimulating hormone (FSH) hormone efficacy and FSHR, CYP19, ESR1 and ESR2 genes using single nucleotide polymorphism analyses. One hundred and seventy women with conserved ovarian function undergoing controlled ovarian stimulation (COS) with daily exogenous recombinant FSH administration. Women were categorized as poor responders to FSH (three or less ovarian follicles observed at the end of cycle) or normal responders (more than three follicles). The outcome is the number of normal/poor responders as defined by the number of follicles obtained during COS. The DNA markers studied are located in genes related to the FSH mechanism of action (FSH receptor, CYP19 aromatase and oestrogen receptors alpha and beta genes). We conducted an association study between the COS outcome and selected DNA markers using two-point and multi-locus genetic association studies. Genotype pattern tracking in extreme phenotypes and multi-locus analysis using Sumstat and PM algorithms provided significant evidences of genetic interaction between FSHR, ESR1 and ESR2 markers in relation to COS outcome (P = 0.0015). Our results support the hypothesis that a discrete set of genes, related to the FSH hormone mechanism of action, controls the ovarian response to FSH in humans. An oligogenic model including specific FSHR, ESR1 and ESR2 genotype patterns may partially explain the poor response to FSH hormone during controlled ovarian stimulation treatments. The existence of genetic heterogeneity is also suspected.

Activation of PKR causes amyloid ß-peptide accumulation via de-repression of BACE1 expression.

BACE1 is a key enzyme involved in the production of amyloid ß-peptide (Aß) in Alzheimer's disease (AD) brains. Normally, its expression is constitutively inhibited due to the presence of the 5'untranslated region (5'UTR) in the BACE1 promoter. BACE1 expression is activated by phosphorylation of the eukaryotic initiation factor (eIF)2-alpha, which reverses the inhibitory effect exerted by BACE1 5'UTR. There are four kinases associated with different types of stress that could phosphorylate eIF2-alpha. Here we focus on the double-stranded (ds) RNA-activated protein kinase (PKR). PKR is activated during viral infection, including that of herpes simplex virus type 1 (HSV1), a virus suggested to be implicated in the development of AD, acting when present in brains of carriers of the type 4 allele of the apolipoprotein E gene. HSV1 is a dsDNA virus but it has genes on both strands of the genome, and from these genes complementary RNA molecules are transcribed. These could activate BACE1 expression by the PKR pathway. Here we demonstrate in HSV1-infected neuroblastoma cells, and in peripheral nervous tissue from HSV1-infected mice, that HSV1 activates PKR. Cloning BACE1 5'UTR upstream of a luciferase (luc) gene confirmed its inhibitory effect, which can be prevented by salubrinal, an inhibitor of the eIF2-alpha phosphatase PP1c. Treatment with the dsRNA analog poly (I∶C) mimicked the stimulatory effect exerted by salubrinal over BACE1 translation in the 5'UTR-luc construct and increased Aß production in HEK-APPsw cells. Summarizing, our data suggest that PKR activated in brain by HSV1 could play an important role in the development of AD.

Multilocus analyses of estrogen-related genes reveal involvement of the ESR1 gene in male infertility and the polygenic nature of the pathology.

OBJECTIVE: To examine whether polymorphisms within the ESR1, FSHR, ESR2, CYP19A1, and NRIP1 genes are susceptibility factors for human male idiopathic infertility and to test the joint effects of these genes on male reproductive function. DESIGN: Genetic association study of male infertility with polymorphisms, using both single-gene and multilocus approaches. SETTING: Private and public fertility units and a private center for biomedical research. PATIENT(S): One hundred four Spanish men with azoospermia or severe oligozoospermia and 95 unselected race-matched healthy controls from the same geographic region. INTERVENTION(S): Peripheral blood extraction, DNA purification, and ESR1 g.938T>C, FSHR Ser680Asn, ESR2 *39A>G, CYP19A1 *19C>T, and NRIP1 Gly75Gly polymorphism analyses. MAIN OUTCOME MEASURE(S): Single-gene statistical analyses and multilocus statistical analyses with Sumstat, Permutation and Model-free analysis, and Estimating Haplotypes software. RESULT(S): We observed an excess of homozygous infertile men for the ESR1 g.938T>C marker. Multilocus analyses detected genetic interaction between the five candidate gene markers that are influential over male infertility. In addition, we detected a five-loci protector genetic pattern with a frequency of 9.4% in controls but absent in infertile men. CONCLUSION(S): Our results support a relevant role for the estrogenic pathway, notably the ESR1 gene, in human male reproductive function and advocate a complex trait model for male infertility.