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At least 55 records · Page 3Linked to original sources
PubMed1975

A heterozygot expression of a 'recessive' gene?

An individual affected with severe bone reductions of the upper limbs, apparently due to an autosomal recessive gene, had eight normal children and then a child with absence of the right thumb and the correspondent metacarpal. This is supposed to be the result of a mild expression of the postulated gene in heterozygous state.

Arm↗
PubMed2006

Wheat leaf chlorosis controlled by a single recessive gene.

The leaf chlorosis in the wheat genotype AIM9 was demonstrated to be controlled by a single recessive gene, which was designated as CD5. Significant difference in physiological and yield indices between chlorotic and non-chlorotic plants were observed in 10 F3 segregating families of the cross combination CN17/AIM9. Correlation analysis of both chlorotic plants and plants staying green of the F3 populations revealed that there was a significant positive correlation between yield index values and the physiological indices net photosynthetic rate (P(n)), stomatal conductance (G(s)), and chlorophyll (Chl), as well as a significant negative correlation between yield index values and the physiological indices intercellular CO2 concentration (C(i)) and malondialdehyde (MDA). Observation using transmission electron microscopy (TEM) found the irreversible centripetal movement of chloroplasts in chlorotic plants, as a result occurred in three sequential events: (1) chloroplast positions changed from face position (with long axis of chloroplasts at the cell walls perpendicular to light ray) to profile position (with long axis chloroplasts near the cell walls parallel to light ray), (2) chloroplast shapes changed from long elliptical to circular, (3) chloroplasts were separated from the cell wall and moved to the center of the cell.

Chlorophyll↗
PubMed1993

Linkage of rhm, a recessive gene for resistance to southern corn leaf blight, to RFLP marker loci in maize (Zea mays) seedlings.

The recessive gene rhm confers chlorotic-lesion resistance to Bipolaris maydis race O, the southern corn leaf blight pathogen, in otherwise susceptible maize plants. Because of inconsistencies encountered in scoring the disease on mature plants in the field, an assay was developed to monitor the expression of this gene in maize seedlings under controlled conditions. One hundred and two related F3 families from the cross RH95rhm x B73 were inoculated with conidia of B. maydis race O, and the genotype at the rhm locus of each F2 parent was deduced from the reactions observed in the progeny seedlings. The F2 genomes were reconstituted by extracting DNA from leaf tissue pooled from 30-36 F3 progeny plants per family. The seedling disease ratings were analyzed together with the segregation scores for 14 single-copy DNA probes. Our results indicate that rhm is tightly linked to two restriction fragment length polymorphism (RFLP) marker loci (UMC85 and p144) that map to the short arm of chromosome 6. In addition, a rapid assay based on the polymerase chain reaction was used to confirm the linkage between rhm and the p144 RFLP marker locus in a second unrelated F2 population.

Ascomycota↗
PubMed1984

Tay-Sachs disease and the persistence of lethal autosomal recessive genes in human populations.

Several lethal autosomal recessive genes have stable carrier frequencies of about 1:20-30 in certain communities, while being exceedingly rare in other, biologically equally successful communities sharing the same environment. It is shown that this situation could persist indefinitely, without invoking the concepts of heterozygote advantage or epistasis, if the parents of affected offspring replace such children with additional sibs. We believe that this could be an important biological mechanism which ensures the maintenance of genetic diversity in the face of natural selection.

Attitude↗
PubMed1991

Is genetic susceptibility to pre-eclampsia conferred by homozygosity for the same single recessive gene in mother and fetus?

OBJECTIVE: To determine whether any simple, purely genetic mechanism can account for susceptibility to pre-eclampsia. DESIGN: Six simple Mendelian models of inheritance were considered, and predictions concerning the incidence of pre-eclampsia in various family members of index cases were calculated for each genetic model. Data were then extracted from published family studies in which a suitable disease definition had been used, and compared to our theoretical expectations. RESULTS: Only one of the genetic models considered, in which both mother and fetus must express the same recessive gene to confer susceptibility, was consistent with the observed incidence values for relatives of index cases. This model was also consistent with the putative association with HLA-DR4, but could not account for the comparative rarity of pre-eclampsia in parous women. CONCLUSION: Homozygosity for a single recessive gene shared by mother and fetus, unlike five other genetic mechanisms tested, is consistent with published family studies in pre-eclampsia, and should be considered the best working hypothesis at present.

Disease Susceptibility↗
PubMed1975

On estimating the frequency of a recessive gene in a random mating population.

The maximum likelihood estimator of the frequency of a recessive gene in a random mating population is simply the square root of the proportion of recessive individuals in a random sample. However, its asymptotic variance, i.e. the inverse of Fisher's information, has an unexpected functional form, and its use may lead to incorrect inferences. An explanation for this is sought by deriving an expansion for the exact variance of the estimator. Further, a number of calculations reveal conditions under which the asymptotic variance provides a reasonable approximation to the exact variance. Lastly, the problem of setting confidence limits to the gene frequency is discussed, with a number of approximations being considered.

Gene Frequency↗
PubMed2006

Molecular mapping of a recessive gene for resistance to stripe rust in barley.

Barley stripe rust, caused by Puccinia striiformis f. sp. hordei, is one of the most important barley (Hordeum vulgare) diseases in the United States. The disease is best controlled using resistant cultivars. Barley genotype Grannenlose Zweizeilige (GZ) has a recessive gene (rpsGZ) that is effective against all races of P. striiformis f. sp. hordei identified so far in the USA. To develop a molecular map for mapping the gene, F(8 )recombinant inbred lines (RILs) were developed from the Steptoe X GZ cross through single-seed descent. Seedlings of the parents and RILs were evaluated for resistance to races PSH-14 and PSH-54 of P. striiformis f. sp. hordei under controlled greenhouse conditions. Genomic DNA was extracted from the parents and 182 F(8 )RILs and used for linkage analysis. The resistance gene analog polymorphism (RGAP) technique was used to identify molecular markers for rpsGZ. A linkage group for the gene was constructed with 12 RGAP markers, of which two markers co-segregated with the resistance locus, and two markers were closely linked to the locus with a genetic distance of 0.9 and 2.0 cM, respectively. These four markers were present only in the susceptible parent. The closest marker to the resistance allele was 11.7 cM away. Analyses of two sets of barley chromosome addition lines of wheat with the two RGAP markers that were cosegregating with the susceptibility allele showed that rpsGZ and the markers were located on the long arm of barley chromosome 4H. Further, tests with four simple sequence repeat (SSR) markers confirmed the chromosomal location of the rpsGZ gene and also integrated the RGAP markers into the known SSR-based linkage map of barley. The closest SSR marker EBmac0679 had a genetic distance of 7.5 cM with the gene in the integrated linkage map constructed with the 12 RGAP markers and 4 SSR markers. The information on chromosomal location and molecular markers for rpsGZ should be useful for incorporating this gene into commercial cultivars and combining it with other resistance genes for durable resistance.

Basidiomycota↗
PubMed1986

Bent-limb disease in lambs. Apparent transmission with an autosomal recessive gene linked to the OL-Z minor lymphocyte antigen locus and the I locus involved in the expression of R and O antigens in sheep.

In crossbred Charmois lambs, Bent-limb disease appears to be associated with the phenotype 'z,i' which corresponds to a doubly recessive genotype at the two loci OL-Z (a minor lymphocyte antigen locus independent of OLA, the major histocompatibility complex of the sheep) and I (involved in genetic control of the expression of R and O antigens found in various body fluids and on erythrocytes). The disease seems to be controlled by a single autosomal recessive gene, provisionally named bl (its normal or healthy allele Bl being dominant) which is distinct from, though linked to, the genes at the OL-Z and I loci (observed haplotype: bl,z,i). In the Lacaune breed, besides the already observed bl,z,i haplotype, there is an additional one: bl,z,I. In Vendéen sheep, and in animals which belong to two other breeds, the bl,Z11,I haplotype (bl linked to the two dominant alleles) appears to be relatively frequent. Further studies are needed in order to confirm the genetic hypothesis suggested by the present data.

Alleles↗
PubMed1991

An autosomal recessive gene that delays expression of lupus in BXSB mice.

We report the generation and serologic, cellular, histologic, and genetic characteristics of a BXSB/MpJScr substrain, termed BXSB/MpJScr-ll/ll, that has lost early-life male lupus disease. Classic genetic analysis suggested that delayed disease expression results from the action of a single autosomal recessive gene. This putative gene, referred to as ll (long-lived), causes a significant delay in expression of autoimmune serology (total serum IgG and anti-nuclear antibodies levels), monocytosis, and of immune complex-mediated histopathologic changes such as glomerulonephritis, arteritis, and myocardial infarction. Presumably as a consequence of the delayed immunopathology male BXSB/MpJScr-ll/ll mice live three to four times longer than regular BXSB/MpJScr. This strain might be useful for analysis of single genes responsible for severe autoimmune disease expression.

Animals↗
PubMed2002

Major recessive gene(s) with considerable residual polygenic effect regulating adult height: confirmation of genomewide scan results for chromosomes 6, 9, and 12.

Segregation and linkage analyses were performed for adult height in a population of 200 Dutch families, each of which was ascertained through a proband with asthma. The best-fit model from the segregation analysis was a major recessive gene with a significant residual polygenic background. Models without a polygenic component were rejected. A genomewide scan was performed, and it confirmed previous linkage results for chromosomes 6q25 (LOD = 3.06, D6S2436), 9p1 (LOD = 2.09, D9S301), and 12q1 (LOD = 1.86, D12S375). Our results provide evidence that a combination of segregation and linkage approaches is valuable in understanding genetic determination of common complex traits.

Adolescent↗
PubMed2000

[Molecular tagging of a new recessive gene for late heading in a rice cultivar 8987].

8987 is a late flowering (lf) indica cultivar. In this study, genetic analysis for lf was carried out in the crosses between 8987 and four varieties with different heading time. Inheritance of lf in F1 plants and F2 populations clearly revealed that the lf of 8987 is controlled by one recessive gene. Bulked-segregant method and cosegregation analysis in F2 population were used to screen molecular markers, which were linked with lf gene. The results showed that the lf gene was mapped between the two RFLP marker C213 and RG404 on chromosome 7. The tagged gene will be utilized in molecular marker assisted selection in the future rice breeding program for new varieties.

Chromosome Mapping↗
PubMed2002

New behavioral mutant rat exhibiting circling behavior (clx) controlled by a sex-linked recessive gene.

A male rat showing intermittent circling behavior was discovered among the Jcl:Wistar rats in our laboratories, and among its backcross offspring individuals showing the same behavior were found. The abnormalities in these animals were characterized by intermittent circling behavior (walking and/or running in circles) and head tossing with the neck twisted. No abnormalities were observed in fertility, delivery or pup mortality. The results of mating experiments indicated that the circling behavior phenotype is controlled by a single sex-linked recessive gene, and the mutant was named "circling behavior linked to X-chromosome (gene symbol: clx)." This circling behavior mutant is considered to be different from the previously reported mutants, the behavior in all of which has been found to be autosomally inherited. Sib-mating is continuing to produce an inbred strain with this newly discovered circling behavior mutant gene.

Animals↗