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PubMed2003

Genetic background of cholesterol gallstone disease.

Cholesterol gallstone formation is a multifactorial process involving a multitude of metabolic pathways. The primary pathogenic factor is hypersecretion of free cholesterol into bile. For people living in the Western Hemisphere, this is almost a normal condition, certainly in the elderly, which explains the very high incidence of gallstone disease. It is probably because the multifactorial background genes responsible for the high incidence have not yet been identified, despite the fact that genetic factors clearly play a role. Analysis of the many pathways involved in biliary cholesterol secretion reveals many potential candidates and considering the progress in unraveling the regulatory mechanisms of the responsible genes, identification of the primary gallstone genes will be successful in the near future.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Endometrial stromal sarcoma--observational evidence of a genetic background?

BACKGROUND: Endometrial stromal sarcomas (ESS) constitute only 0.2% of all gynecological malignancies, and risk factors or genetic associations are largely unknown. We are in contact with more than 100 patients with ESS via an internet support group, and our aim was to analyze the personal and familial medical histories of this large patient group for possible familial cancers aggregations in ESS patients. METHODS: A questionnaire regarding the personal and familial medical history was circulated among the members of the internet group, which was returned by 64 patients. RESULTS: At diagnosis of ESS the average age was 42 years. Fifty percent had a history of long-term hormonal treatment. One patient each had a previous history of breast carcinoma, thyroid cancer and cutaneous malignant melanoma. One familial case of ESS was observed. At least one malignancy in the family was reported by 47% of patients, and the mother or father were affected in 26%. Multiple familial cancers were observed in 25% of ESS patients. The most frequent familial cancer was breast cancer (25%) followed by endometrial (8%), lung (7%) and prostate carcinoma (5%). CONCLUSIONS: Patients are young, report hormonal treatments and have a familial history of hormone-dependent carcinomas. This suggests a strong genetic predisposition in the oncogenesis of ESS. Patients with ESS may suffer from an inherited genetic predisposition similar to familial breast and prostate carcinoma which may render them susceptible to hormone-dependent growth promotion and/or to cellular damage from particular estrogen metabolites of endometrial cells resulting in a ESS.

Adult↗
PubMedDate not supplied

[Genetic background of ADHD: genes of the serotonergic system, other candidate genes, endophenotype].

Recent studies have shown that in the aetiology of attention-deficit hyperactivity disorder (ADHD) genetic factors may be of importance. Biochemical and pharmacological studies reveal a connection between abnormalities of dopaminergic, adrenergic and serotonergic system and ADHD. Therefore genes for enzymes synthesizing or degrading proper neurotransmitters, genes for adequate transporters and receptors and genes for other substances, which altered the level of neurotransmitters, are studied. Many authors describe the connection between ADHD development and the synaptosomal-associated protein 25 (SNAP-25) gene. This protein plays a role in catecholamine secretion. Its higher expression is specific for neurones. SNAP-25 gene mutation may change this protein level, function of synapse and neurotransmitters storage. Acetylcholine receptor alpha4 subunit gene stimulation increases the dopamine level. Therefore this receptor gene may be important in the aetiology of ADHD studies. Other possible factors in ADHD background are substance influence on brain maturation, including N-methyl-D aspartate glutamate receptor 2A gene polymorphism (GRIN2A) and brain derived neurotrophic factor (BDNF) gene. One of the greatest challenges in studying the genetic basis of psychiatric disorders is to find appropriate ways to define the relevant endophenotype. ADHD often coexists with other psychiatric disorders, including specific developmental disorders, conduct disorders, obsessive-compulsive disorder and early onset of bipolar disorder.

Attention Deficit Disorder with Hyperactivity↗
PubMed2006

Bayes factor for testing the genetic background of quantitative threshold traits.

The recent development of the Bayes factor methodology to test between nested competing models has allowed to evaluate the genetic component of continuous traits through a methodology based on the reparameterization of a variance component model in terms of intra-class correlation. In this study, we present a modification of that procedure to compare between threshold models that only differ in a bounded variable. An extra data-augmentation step is required to sample liability, an underlying continuous variable related with phenotypic records through an adequate number of thresholds. In this context, we describe a procedure to sample from a truncated multivariate normal distribution with non-null covariances between records, taking as starting point the Cholesky factorization and the inclusion of linear restrictions. The method was tested by computer simulations with satisfactory results.

Animals↗
PubMed1989

Genetic background and development of skin tumors.

Inbred mouse strains that differing widely in their susceptibility to multistage skin carcinogenesis provide useful models for studying the genetic factors involved and advancing our understanding of the biochemical and molecular events associated with this process. The process of skin tumor initiation appears to be somewhat similar in various strains of mice, and most data in the literature suggest that differences in response to skin tumor promoters are a major determinant in controlling susceptibility to multistage skin carcinogenesis. A model system has been developed for examining the genetics of susceptibility to skin tumor promotion. The susceptibility to phorbol ester skin tumor promotion in crosses between DBA/2 and C57BL/6 mice is inherited as an incomplete dominant trait, and neither X-chromosome nor cytoplasmic genetic determinants appear to play a major role in determining susceptibility in these two inbred strains. In addition, two or more genetic loci contribute to the higher sensitivity of DBA/2 mice than C57BL/6 mice to TPA-induced skin tumor promotion. Further studies to characterize these genes will contribute greatly to our understanding of the mechanisms of phorbol ester skin tumor promotion. In addition, much work should now be directed at understanding the cellular, biochemical, and molecular mechanisms for differential responsiveness not only to phorbol esters but also to other classes of tumor promoters.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Effect of genetic background on the therapeutic effects of dehydroepiandrosterone (DHEA) in diabetes-obesity mutants and in aged normal mice.

Dehydroepiandrosterone (DHEA) was fed at 0.1-0.4% in the diet to genetically diabetic (db/db) or obese (ob/ob) C57BL/KsJ (BL/Ks) or C57BL/6J (BL/6) mice. Treatment of BL/Ks-db/db or ob/ob mice with 0.4% DHEA prevented hyperglycemia, islet atrophy, and severe diabetes associated with this inbred background, but did not affect weight gain and food consumption. Homozygous obese (ob) or diabetes (db) mice on the BL/6 background were more sensitive to DHEA, and the mild, transient hyperglycemia associated with ob or db gene expression on the BL/6 inbred background could be prevented by 0.1% DHEA. Both body weight and food consumption were decreased in BL/6 mutants maintained on 0.1% DHEA whereas this effect was not seen in BL/Ks mutants fed up to 0.4% DHEA. Early therapy with 0.4% DHEA, initiated at 2 wk of age, prevented the development of most diabetes symptoms and decreased the rate of weight gain in pups of all genotypes. In addition to therapeutic effects on both obese mutants, DHEA effected significant changes in an aging study using normal BL/6 female mice. Four weeks of DHEA treatment initiated at 2 yr of age improved glucose tolerance and at the same time reduced plasma insulin to a "younger" level. This suggests that DHEA may act in insulin-resistant mutant mice and in aging normal mice to increase the sensitivity to insulin.

Aging↗
PubMed2002

[Genetic background of sarcoidosis--special reference to HLA].

A comprehensive epidemiological study (ACCESS) recently conducted in the United States has recognized modest familial aggregation of sarcoidosis. Therefore, genetic factors, in particular human leukocyte antigens (HLAs) are believed to be important determinants of susceptibility to sarcoidosis. A previous case-control study on Japanese population has postulated that an amino acid, serine, at position 11 of beta subunit of HLA-DR confers susceptibility to sarcoidosis. Whereas, a more recent study suggests that protective HLA-DR alleles, which encode the DR1 and DR4 antigens, were found to share characteristic small hydrophobic residues at the same position. Meanwhile, the first genome scan on sarcoidosis has found the highest linkage score in the class III region, where HLA-DR genes do not exist. Complete clarification of genetic mechanisms of sarcoidosis awaits the precise identification of causative antigens, if any.

Genetic Markers↗
PubMed2006

Marker-assisted selection and evaluation of the QTL for stigma exsertion under japonica rice genetic background.

Stigma exsertion is one of the important traits which contribute to the efficient improvement of commercial seed production in hybrid rice. In order to understand the genetic factors involved in the stigma exsertion of an indica variety--IR24--a QTL analysis was conducted using the F2 population between a japonica variety--Koshihikari--and a breeding line showing exserted stigma selected from the backcross population between IR24 as a donor and japonica varieties. As a result, a highly significant QTL (qES3), which had been predicted in the recombinant inbred population of IR24, was confirmed at the centromeric region on chromosome 3. qES3 increases about 20% of the frequency of the exserted stigmas at the IR24 allele and explains about 32% of the total phenotypic variance. A QTL near-isogenic line for qES3 increased the frequency of the exserted stigma by 36% compared to that of Koshihikari in a field evaluation, which suggests that qES3 is a promising QTL for the development of a maternal line for hybrid rice.

Agriculture↗