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PubMed2004

Genetics of hypercalciuria and calcium nephrolithiasis: from the rare monogenic to the common polygenic forms.

Idiopathic calcium nephrolithiasis is a multifactorial disease with a pathogenesis that involves a complex interaction of environmental and individual factors. This review discusses what is known about monogenic renal calcium stone-related disorders, provides an update on genetic research in calcium nephrolithiasis and such intermediate phenotypes as idiopathic hypercalciuria, discusses the problems that these conditions pose to clinicians and geneticists interested in their pathogenesis, and proposes some method tools potentially useful in this research frame of reference.

Animals↗
PubMed1981

Models of speciation by sexual selection on polygenic traits.

The joint evolution of female mating preferences and secondary sexual characters of males is modeled for polygamous species in which males provide only genetic material to the next generation and females have many potential mates to choose among. Despite stabilizing natural selection on males, various types of mating preferences may create a runaway process in which the outcome of phenotypic evolution depends critically on the genetic variation parameters and initial conditions of a population. Even in the absence of genetic instability, rapid evolution can result from an interaction of natural and sexual selection with random genetic drift along lines of equilibria. The models elucidate genetic mechanisms that can initiate or contribute to rapid speciation by sexual isolation and divergence of secondary sexual characters.

Journal Article↗
PubMed1984

Group selection for a polygenic behavioral trait: estimating the degree of population subdivision.

For assessing the degree of population subdivision, and therefore the extent to which group selection might favor an altruistic trait, an appropriate measure is Nei's GST, defined by (F0-F)/(1-F). F0 is the probability that two alleles drawn from the same group are identical in state and F is the probability for two alleles drawn at random from the entire population. These probabilities can be assessed from molecular polymorphisms. GST has a number of properties that make it useful for empirical studies. When the mutation rate is small relative to the migration rate and the reciprocal of the group size, GST depends mainly on the absolute number of migrants per generation, moves rapidly to near equilibrium, and is independent of the number of alleles. The relative homogenizing effect of migration in the island and stepping-stone models is not as different as might be expected; one immigrant chosen randomly from the rest of the population is only one to two times as effective as one from a neighboring group, appreciably exceeding 2 only when there are 1000 or more groups. The use of molecular data to estimate the degree of population subdivision may permit testable predictions of the extent of altruistic behavior.

Alleles↗
PubMed2003

Functional complementation between a novel mammalian polygenic transport complex and an evolutionarily ancient organic solute transporter, OSTalpha-OSTbeta.

These studies identify an organic solute transporter (OST) that is generated when two novel gene products are co-expressed, namely human OSTalpha and OSTbeta or mouse OSTalpha and OSTbeta. The results also demonstrate that the mammalian proteins are functionally complemented by evolutionarily divergent Ostalpha-Ostbeta proteins recently identified in the little skate, Raja erinacea, even though the latter exhibit only 25-41% predicted amino acid identity with the mammalian proteins. Human, mouse, and skate OSTalpha proteins are predicted to contain seven transmembrane helices, whereas the OSTbeta sequences are predicted to have a single transmembrane helix. Human OSTalpha-OSTbeta and mouse Ostalpha-Ostbeta cDNAs were cloned from liver mRNA, sequenced, expressed in Xenopus laevis oocytes, and tested for their ability to functionally complement the corresponding skate proteins by measuring transport of [3H]estrone 3-sulfate. None of the proteins elicited a transport signal when expressed individually in oocytes; however, all nine OSTalpha-OSTbeta combinations (i.e. OSTalpha-OSTbeta pairs from human, mouse, or skate) generated robust estrone 3-sulfate transport activity. Transport was sodium-independent, saturable, and inhibited by other steroids and anionic drugs. Human and mouse OSTalpha-OSTbeta also were able to mediate transport of taurocholate, digoxin, and prostaglandin E2 but not of estradiol 17beta-d-glucuronide or p-aminohippurate. OSTalpha and OSTbeta were able to reach the oocyte plasma membrane when expressed either individually or in pairs, indicating that co-expression is not required for proper membrane targeting. Interestingly, OSTalpha and OSTbeta mRNAs were highly expressed and widely distributed in human tissues, with the highest levels occurring in the testis, colon, liver, small intestine, kidney, ovary, and adrenal gland.

Amino Acid Sequence↗
PubMed1988

Familial links between schizophrenia and other disorders: application of the multifactorial polygenic model.

A substantial number of patients do not meet diagnostic criteria for schizophrenia yet exhibit psychotic phenomena characteristic of that disorder (e.g., schizophreniform disorder, schizoaffective disorder, paranoid disorder, atypical psychosis). The relationship between schizophrenia and these disorders is poorly understood. This paper describes how the two-threshold multifactorial model of familial transmission can be applied to test the hypothesis that these disorders share a multifactorial etiology with schizophrenia. The procedure is illustrated using data from a blind family study of the major psychoses. Results support the hypothesis that the disorders under examination share a common multifactorial familial etiology. Methodological issues are discussed along with suggestions for future research in this area.

Adult↗
PubMedDate not supplied

Lung function in an Australian population: contributions of polygenic factors and the Pi locus to individual differences in lung function in a sample of twins.

A study of lung function in 203 twin pairs aged 18-34 years living in Sydney detected significant genetic variation in females and males. There was no evidence of family environmental effects in either sex and most of the repeatable variation in females was heritable. However, there was evidence for systematic environmental differences between males affecting lung function so that the heritability was lower in males (about 0.6) than females (about 0.8). An effect of smoking on lung function was detected but accounted for less than 3% of the variance. Lung function in females was greater in the M subtype heterozygotes at the Pi locus than in the M subtype homozygotes or in other Pi phenotypes with low alpha 1-antitrypsin activity. The Pi polymorphism accounted for approximately 9% of the total variance in female lung function. No effect of the Pi locus was found in males.

Adolescent↗
PubMed2000

Effects of HFE C282Y and H63D polymorphisms and polygenic background on iron stores in a large community sample of twins.

The aim of this study was to assess and to compare the role of HFE polymorphisms and other genetic factors in variation in iron stores. Blood samples were obtained from 3,375 adult male and female twins (age range 29-82 years) recruited from the Australian Twin Registry. There were 1,233 complete pairs (562 monozygotic and 571 dizygotic twins). Serum iron, transferrin, transferrin saturation with iron, and ferritin were measured, and the HFE C282Y and H63D genotypes were determined. The frequency of the C282Y allele was.072, and that of the H63D allele was.141. Significant sources of variation in the indices of iron status included age, sex, age-sex interaction, body-mass index, and both the C282Y and H63D genotypes. The iron, transferrin, and saturation values of CC and CY subjects differed significantly, but the ferritin values did not. After correction for age and body-mass index, 23% and 31% of the variance in iron, 66% and 49% of the variance in transferrin, 33% and 47% of the variance in transferrin saturation, and 47% and 47% of the variance in ferritin could be explained by additive genetic factors, for men and women, respectively. HFE C282Y and H63D variation accounted for <5% of the corrected phenotypic variance, except for saturation (12% in women and 5% in men). We conclude that HFE CY and HD heterozygotes differ in iron status from the CC and HH homozygotes and that serum transferrin saturation is more affected than is serum ferritin. There are highly significant effects of other as-yet-unidentified genes on iron stores, in addition to HFE genotype.

Adult↗
PubMed2002

Skilled use of DNA polymorphisms as a tool for polygenic cancers.

Association studies are assumed to be an efficient method of deciding whether a gene or its variant is important for cancer. Sequencing data on 30 000 human genes suggest that an average gene contains one to two single nucleotide polymorphisms (SNP), and high through-put technologies have become available for fast genotyping. Because no functional data are available for most SNPs, the result of the large-scale genotyping effort will be a huge amount of data of unknown biological significance. We discuss here the approaches in study design and reporting that will reduce the spread of false positive data and optimize scientific progress in the genotyping field.

False Positive Reactions↗