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At least 523 records · Page 29Linked to original sources

PubMed2003

[The microencapsulated genetic engineering cells: a new platform on treatment of cancer instead of genetic engineering drugs].

The microencapsulated genetic cells may be a new platform instead of genetic engineering drugs, as they can overcome the genetic engineering drugs' shortages such as short half-life in vivo, low activity, and incomplete elimination of organic solvent. This article reviews and summarizes the advantages, possible problems and solution and the feasibility of using microencapsulated genetic engineering cells in the treatment of cancer.

Animals↗

PubMed1991

Genetic epidemiology of non-insulin-dependent diabetes mellitus in north India: preliminary analyses of some genetic markers in Punjabis.

Studies on monozygotic (MZ) twins and admixed populations show that the predisposition to non-insulin-dependent diabetes mellitus has a large genetic component. We have examined the distribution of some genetic polymorphisms (ABO, GLO, ESD, AK, ACPA, and GPI) in control and diabetic Punjabis from north India. The distribution of various genetic markers indicate that the differences between the control and diabetic samples are statistically not significant. Moreover, a contingency chi-square analysis over all loci suggests nonsignificant genetic differentiation (p = 0.50) between the Punjabi samples.

Adult↗

PubMed1984

Genetic engineering, medicine and medical genetics.

The impact of DNA technology in the near future will be on the manufacture of biologic agents and reagents that will lead to improved therapy and diagnosis. The use of DNA technology for prenatal and preclinical diagnosis in genetic diseases is likely to affect management of genetic diseases considerably. New and old questions regarding selective abortion and the psychosocial impact of early diagnosis of late appearing diseases and of genetic susceptibilities are being raised. Somatic therapy with isolated genes to treat disease has not been achieved. True germinal genetic engineering is far off for humans but may find applications in animal agriculture.

Genetic Engineering↗

PubMed1980

Population genetics in the state of Nuevo León, Mexico. II. Genetic markers, frequencies and their possible association with chromosome damage in workers exposed to lead.

In order to find out genetic variability and its possible association with chromosomic damage, we studied the ABO, Rh and MN blood groups as well as the ability to taste PTC, ear lobe type and mid-digital hair, in 77 workers exposed to lead oxides. 23 people who worked near the source of lead (internal control) and 20 people not exposed to lead (external control). From each person a blood sample was taken for chromosome analysis in cultured lymphocytes and for lead determination, at the same time an urine sample was taken for delta-aminolevulinic acid (ALA) determinations; at the same time an urine sample increased chromosome damage, blood lead levels and urinary ALA, were found as compared with both controls. Differences were statistically significant. As for genetic marker frequencies differences were found only for the Rh factor, between the internal control and both the external control and exposed workers. No significant association was found between genetic markers and chromosome damage. Association was observed between blood lead levels, and urinary ALA with some genetic markers like ABO and MN blood groups and ear lobe type.

Chromosome Aberrations↗

PubMed1994

Ionizing radiation and genetic risks. V. Multifactorial diseases: a review of epidemiological and genetic aspects of congenital abnormalities in man and of models on maintenance of quantitative traits in populations.

This paper discusses (a) data on the epidemiological and etiological aspects of human congenital abnormalities, (b) the multifactorial threshold model and other models which have been proposed to explain their inheritance patterns and recurrence risks in families and (c) current concepts on mechanisms on the prevalence of heritable variation for quantitative traits in populations. Congenital abnormalities, which afflict an estimated 6% of all live births, are etiologically heterogeneous. The majority of these do not follow Mendelian transmission patterns, but do 'run' in families. The multifactorial threshold model is an extension of genetic principles developed for quantitative traits to all-or-none traits; in its simplest formulation, it assumes the existence in the population of an underlying normally distributed 'liability' (which is due to numerous genetic and environmental factors acting additively, each contributing a small amount of liability) and of a 'threshold' beyond which the individual is affected. For most congenital abnormalities, the nature of these factors remains unknown. Other models assume fewer causal factors although, again, these remain to be identified. The question of how considerable heritable variation for most quantitative/polygenic traits has come to exist is a long-standing one in evolutionary population genetics. Models postulating that its existence is consistent with a balance between recurrent mutation and stabilizing selection or suggesting the possible operation of other mechanisms have been published in the literature. In the absence of knowledge on mechanisms responsible for the stable prevalences of congenital abnormalities or other multifactorial conditions in the population (but which is required to predict the consequences of an increase in mutation rate on their prevalences) it is necessary (a) to adapt and use concepts derived from quantitative and evolutionary population genetics and (b) to examine how sensitive the predictions are to the assumptions used, and how consistent they are with biological realities.

Abnormalities, Radiation-Induced↗

PubMed1994

Genetic characterization of the Cayapa Indians of Ecuador and their genetic relationships to other Native American populations.

One-hundred sixty-four Cayapa Indians living in the Esmeraldas Province (northwest Ecuador) were studied for several erythrocyte genetic markers (ACP1, ADA, AK1, CA2, ESD, GLO1, G6PD, PGD, PGM1 subtyping and thermostability, PGM2, SODA, and HB). The Cayapa show allele frequencies typical of those of South American Indians. The absence of the CA2*2, G6PD*A, G6PD*A-, HBB*S, and HBB*C alleles and the low PGM1*1A and PGM1*2A and high PGM1*1B allele frequencies indicate that very little (no more than 2%), if any, genetic admixture has occurred with the black community living in the same area. Correspondence analysis was used to study the genetic relationships between the Cayapa and other linguistically defined Amerind populations and between the Amerinds and the other two native American groups, the Na-Dene and Eskimo-Aleut. The results of this analysis, obtained on the basis of some erythrocyte and serum markers and some blood group systems, show (1) the close affinity between the Cayapa and other South American populations, (2) the absence in the Amerind group of a clear-cut correspondence between linguistic classification and genetic relatedness, and (3) the evident distinctiveness of the Amerinds from other native American people.

Adult↗

PubMed1998

Beta-2 adrenoceptor genetic variation is associated with genetic predisposition to essential hypertension: The Bergen Blood Pressure Study.

We tested the hypothesis that genetic variation in the beta-2 adrenoceptor gene is associated with a genetic predisposition to hypertension. Offspring of two hypertensive parents were compared with offspring of two normotensive parents. The subjects were participants of the Bergen Blood Pressure Study, where couples were recruited in 1963 to 1964 and re-examined in 1990. We studied offspring of those couples in which both partners were either hypertensive or normotensive in both examinations. Twenty-three hypertensive and 22 normotensive families met the inclusion criteria. DNA samples from the first born of hypertensive family-history offspring and normotensive family-history offspring were analyzed. We used multiplex sequencing and specifically examined the promoter and the N-terminal portion of the beta-2 adrenoceptor gene. We found four genetic variants: at position -47, a C-->T substitution in the 5' leader cistron causing an Arg-->Cys exchange, at -20, a T-->C substitution, at +46 an A-->G substitution leading to an Arg16-->Gly exchange, and at +79, a C-->G substitution leading to a Gln27-->Glu exchange. The frequency of the Arg16 allele was significantly higher in the hypertensive family-history offspring compared to normotensive family-history offspring (58% vs. 28% P < 0.011). We constructed haplotypes for the four intragenic variants and found significant linkage dysequilibrium. In particular, the 5' leader cistron mutant with the wild type alleles at the other loci was significantly more frequent in offspring of hypertensive parents, compared to offspring of normotensive parents. We also performed a relative risk analysis comparing the Gly/Gly, Arg/Gly, and Arg/Arg alleles, which implicated the Arg-containing allele. Finally, we analyzed the effect of genotype on blood pressure in the offspring. We found a significant step-wise effect for all four polymorphisms examined. Our data suggest that the Arg variant of the Arg-->Gly exchange is associated with parental hypertension and higher blood pressure values in this northern European population.

Adult↗

PubMed2005

[Congenital hearing loss. Molecular genetic diagnosis of connexin genes and genetic counselling].

BACKGROUND: About 50% of congenital non-syndromic hearing impairment is caused by genetic factors. Research on the genetics of deafness has revealed a vast number of relevant genes. Mutations in the GJB2 gene have been shown to be the most common in several populations. METHODS: Mutation analysis of the genes for connexin 26, 30 and 31 (GJB2, GJB6 and GJB3) was performed in 67 patients with profound hearing loss. RESULTS: Of the participants, 9% had two pathogenic mutations in the GJB2 gene. Pedigree information indicates that in these families further offspring have a 25% to a 100% chance of having hearing impairment. CONCLUSIONS: Patients with non-syndromic hearing impairment should be offered molecular diagnostics of the GJB2 gene. Genetic counseling is mandatory for mutation carriers in order to advise them on the individual consequences of the gene test results.

Connexin 26↗

PubMed2006

Quantitative genetics of speciation: additive and non-additive genetic differentiation between Drosophila madeirensis and Drosophila subobscura.

The role of dominance and epistasis in population divergence has been an issue of much debate ever since the neoDarwinian synthesis. One of the best ways to dissect the several genetic components affecting the genetic architecture of populations is line cross analysis. Here we present a study comparing generation means of several life history-traits in two closely related Drosophila species: Drosophila subobscura, D. madeirensis as well as their F1 and F2 hybrids. This study aims to determine the relative contributions of additive and non-additive genetic parameters to the differentiation of life-history traits between these two species. The results indicate that both negative dominance and epistatic effects are very important in the differentiation of most traits. We end with considerations about the relevance of these findings for the understanding of the role of non-additive effects in speciation.

Animals↗

PubMed2006

Genetic dissection of intermated recombinant inbred lines using a new genetic map of maize.

A new genetic map of maize, ISU-IBM Map4, that integrates 2029 existing markers with 1329 new indel polymorphism (IDP) markers has been developed using intermated recombinant inbred lines (IRILs) from the intermated B73xMo17 (IBM) population. The website http://magi.plantgenomics.iastate.edu provides access to IDP primer sequences, sequences from which IDP primers were designed, optimized marker-specific PCR conditions, and polymorphism data for all IDP markers. This new gene-based genetic map will facilitate a wide variety of genetic and genomic research projects, including map-based genome sequencing and gene cloning. The mosaic structures of the genomes of 91 IRILs, an important resource for identifying and mapping QTL and eQTL, were defined. Analyses of segregation data associated with markers genotyped in three B73/Mo17-derived mapping populations (F2, Syn5, and IBM) demonstrate that allele frequencies were significantly altered during the development of the IBM IRILs. The observations that two segregation distortion regions overlap with maize flowering-time QTL suggest that the altered allele frequencies were a consequence of inadvertent selection. Detection of two-locus gamete disequilibrium provides another means to extract functional genomic data from well-characterized plant RILs.

Alleles↗

PubMed1975

Population genetics of euphydryas butterflies. I Genetic variation and the neutrality hypothesis.

Twenty-one populations of the checkerspot butterfly, Euphydryas editha, and ten populations of Euphydryas chalcedona were sampled for genetic variation at eight polymorphic enzyme loci. Both species possessed loci that were highly variable from population to population and loci that were virtually identical across all populations sampled. Our data indicate that the neutrality hypothesis is untenable for the loci studied, and therefore selection is indicated as the major factor responsible for producing these patterns. Thorough ecological work allowed gene flow to be ruled out (in almost all instances) as a factor maintaining similar gene frequencies across populations. The Lewontin-Krakauer test indicated magnitudes of heterogeneity among standardized variances of gene frequencies inconsistent with the neutrality hypothesis. The question of whether or not to correct this statistic for sample size is discussed. Observed equitability of gene frequencies of multiple allelic loci was found to be greater than that predicted under the neutrality hypothesis. Genetic differentiation persisting through two generations was found between the one pair of populations known to exchange significant numbers of individuals per generation. Two matrices of genetic distance between populations, based on the eight loci sampled, were found to be significantly correlated with a matrix of environmental distance, based on measures of fourteen environmental parameters. Correlations between gene frequencies and environmental parameters, results of multiple regression analysis, and results of principle component analysis showed strong patterns of association and of "explained" variation. The correlation analyses suggest which factors might be further investigated as proximate selective agents.

Animals↗

PubMed1996

Genetic composition of Chilean aboriginal populations: HLA and other genetic marker variation.

Phenotypes and gene frequencies for eight genetic systems are presented for five Chilean Indian tribes. Results agree with the pattern expected for Andean Indians. Genetic distances and dendrograms were obtained separately for HLA and traditional genetic markers. The similarity of both is noteworthy. Linguistic distances exhibit a correlation with genetic distances based on traditional markers.

Chile↗

PubMed1988

Genetic and environmental components of serum creatine kinase (CK) and pyruvate kinase (PK) in normal twins: implication for genetic risks estimates in Duchenne muscular dystrophy carriers.

The serum activity of creatine kinase (CK) and pyruvate kinase (PK) was measured in 98 pairs of same-sex Brazilian twins. The purpose of this study was to estimate the genetic and environmental components of serum activity levels for both enzymes. Heritabilities were estimated separately by path analysis in each sex. The results showed that CK and PK activities are under genetic control in normal males and females. Environmental components were not statistically significant for CK or PK. The genetic component of both enzymes estimated in females has implications in the calculation of genetic risks for Duchenne muscular dystrophy carriers.

Creatine Kinase↗

PubMed1992

Comparison of couples referred and not referred for genetic counseling in a genetic clinic after the birth of a child with a congenital anomaly: a study in a population in the northeastern Netherlands.

After the birth of a child with a congenital anomaly, parents have many questions about cause, prognosis, and recurrence risk. An important means of transmitting such information is referral to a genetic clinic. We were interested in knowing what determines whether or not parents are referred for genetic counseling. Data from the local registration of congenital anomalies in the northeastern Netherlands (birth years 1981-1986; 1,217 children/fetuses) and data of the local genetic clinic were compared. The parents of 204 cases (16.8%) had been referred for genetic counseling. Of the couples referred, 76% were referred within one year after birth, usually by a pediatrician (48%). Parents of children with a single anomaly, recognized syndrome, or multiple anomalies not recognized as a syndrome were referred in 5%, 43%, and 26% of cases, respectively. Parents of liveborn children who died were referred in 38% of cases, parents of liveborn/still-alive and stillborn children in 13% and 22%, respectively. Previous affected sibs and absence of previous livebirths increased the likelihood of referral.

Congenital Abnormalities↗

PubMed1994

Distinguishing genetic disease and genetic susceptibility.

With the increasing awareness of the involvement of genetic factors in disease, questions arise as to what distinguishes genetic from non-genetic disease, and what constitutes a genetic susceptibility. A general framework, reflecting the structure of biological explanations, is presented in which such distinctions can be made. We conclude that such distinctions are objective and are based on the biological facts; they are not "social constructions" nor do they presuppose resolution of philosophical problems regarding causation.

Congenital Abnormalities↗

PubMed1997

Interpatient variability: genetic predisposition and other genetic factors.

Polymorphisms and other genetic factors related to enzymes metabolizing drugs and xenobiotic chemicals are well known. This article focuses on selected molecular mechanisms and introduces some of the clinical implications arising from genetically determined interpatient variability or expression in some of these enzymes. Selected are the polymorphic enzymes of cytochromes P-450 (CYP) as examples of phase I enzymes and methyl transferases, n-acetyl transferases, and glutathione-s-transferases as examples of phase II enzymes. The polymorphism surrounding arylhydrocarbon hydroxylase induction is briefly described. Phase I enzymatic reactions are predominantly oxidative, whereas phase II reactions often couple with the byproducts of phase I. Overall, in poor metabolizers, whether phase I or phase II, there is limited metabolism in most patients unless another major metabolic pathway involving other enzymes exists. Drug metabolism also depends on whether the parent compound is a prodrug that forms an active metabolite, and poor metabolizers under this condition will form only trace amounts of an active compound. Therefore, the clinical significance of genetic polymorphisms and other genetic factors may be related to substrate, metabolite, or the major elimination pathway.

Cytochrome P-450 Enzyme System↗

PubMed2004

Genetic diversity of influenza B virus: the frequent reassortment and cocirculation of the genetically distinct reassortant viruses in a community.

To characterize the genetic diversity of influenza B viruses isolated during one influenza season, the antigenic and genetic relationships among 20 strains of influenza B virus isolated in February and March 2001 at one pediatric clinic in Yamagata City, Japan, were investigated. The HA gene and seven other gene segments were phylogenetically divided into three distinct sublineages (Harbin/7/94-, Tokyo/6/98-, and Shiga/T30/98-related lineage) of the Yamagata/16/88-like lineage. The NS genes of the viruses belonging to the Harbin/7/94-related lineage have additional three nucleotides at positions 439-447, and were phylogenetically distinguishable from those of the currently circulating Yamagata/16/88- and Victoria/2/87-like lineages, but were closely related to that of the Yamagata/16/88-like lineage isolated before 1994. Moreover, four strains of influenza B virus isolated in the same community between 2002 and 2003 were further examined. Phylogenetic analysis revealed that a virus of Victoria/2/87-like lineage isolated in 2003 had acquired the NA, NS, M, and PA gene segments from a Shiga/T30/98-like virus, and two strains of Harbin/7/94-related lineage had acquired the various gene segments from Shiga/T30/98-like virus through a reassortment event. These results indicate that genetically distinct multiple viruses can combine to cause an influenza B epidemic in a community and that the frequent reassortment among these viruses plays a role in generating the genetic diversity of influenza B viruses.

Adolescent↗

PubMed2005

Bayesian implementation of a genetic model-free approach to the meta-analysis of genetic association studies.

A genetic model-free method for the meta-analysis of genetic association studies is described that estimates the mode of inheritance from the data rather than assuming that it is known. For a bi-allelic polymorphism, with G as risk allele and g as wild-type, the genetic model depends on the ratio of the two log odds ratios, lambda = log OR(Gg)/log OR(GG), where OR(GG) compares GG with gg and OR(Gg) compares Gg with gg. Modelling log OR(GG) as a random effect creates a hierarchical model that can be implemented within a Bayesian framework. In Bayesian modelling, vague prior distributions have to be specified for all unknown parameters when no external information is available. When the data are sparse even supposedly vague prior distributions may have an influence on the posterior estimates. We investigate the impact of different vague prior distributions for the between-study standard deviation of log OR(GG) and for lambda, by considering three published meta-analyses and associated simulations. Our results show that depending on the characteristics of the meta-analysis the results may indeed be sensitive to the choice of vague prior distribution for either parameter. Genetic association studies usually use a case-control design that should be analysed by the corresponding retrospective likelihood. However, under some circumstances the prospective likelihood has been shown to produce identical results and it is usually preferred for its simplicity. In our meta-analyses the two likelihoods give very similar results.

Bayes Theorem↗