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PubMed1994

Radiation hypersensitivity of LEC strain rats controlled by a single autosomal recessive gene.

LEC strain rats (LEC rats), which are known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation when compared to WKAH strain rats. The radiosensitivity of F1 hybrids of LEC and WKAH rats was similar to that of WKAH rats and significantly lower than that of LEC rats. Segregation data of backcross hybrids (F1 x LEC and LEC x F1) suggested that the hypersensitivity of LEC rats to whole-body irradiation is controlled by a single autosomal recessive gene. The radiosensitivity of fibroblasts from LEC rats was higher than that of fibroblasts from WKAH rats. The repair process of DNA double-strand breaks in LEC cells was slower than that in WKAH cells. LEC rats could provide a useful animal model to assist in understanding the mechanism of radiation-induced DNA damage and repair.

Animals↗

PubMed1988

Hereditary hepatitis of LEC rats is controlled by a single autosomal recessive gene.

The natural history of hereditary hepatitis in long-survived LEC rats was reported. Among 56 (female: male, 28:28) LEC rats of F30, 16 (8:8) (29%) died of fulminant hepatitis approximately four months after birth. The remaining 40 (20:20) rats that survived more than one year developed chronic hepatitis and subsequent hepatic lesions including hepatocellular carcinomas. Further study made with 32 F31 rats killed at the age of five months revealed that hepatitis occurred in all of these rats. Genetic analysis performed by various crosses of LEC and LEJ rats confirmed the previous result that hereditary hepatitis was caused by a single autosomal recessive gene. F1 hybrid rats never developed hepatitis, showing normal histology of the liver. Histological features of hepatitis in F2 (F1 X F1) and backcross (F1 X LEC) rats were the same as those observed in the LEC rats. The preneoplastic foci also appeared in some of these hybrid rats at the age of eight months. We propose a gene symbol hts to designate the present hepatitis which is assumed to be homozygous in LEC strain rats.

Animals↗

PubMedDate not supplied

Two recessive gene inheritance for triallate resistance in Avena fatua L.

Extensive use of the preemergence herbicide triallate over the last three decades has selected for resistant (R) Avena fatua L. populations in several areas of the United States and Canada. R plants are also cross-resistant to the unrelated pyrazolium herbicide difenzoquat. We made reciprocal crosses between inbred R and susceptible (S) lines to determine the genetic basis of triallate resistance. Seeds from parental lines and F(2) populations were treated with soil applications of 0.275, 0.55, or 1.1 kg/ha triallate in the greenhouse and plant heights recorded after 37 days. Surviving F(2) plants were selfed and the resulting F(3) families were screened with 1.1 kg/ha triallate. In the F(2) populations, assortment of S and R phenotypes fit a 15:1 segregation ratio, suggesting that resistance was controlled by the two independently segregating recessive genes TRR1 and TRR2. None of the 912 F(3) progeny from 51 R F(2) individuals was susceptible to triallate treatment, further supporting a two-gene mode of inheritance. There was a possible maternal effect on susceptibility at the highest triallate rate tested.

Avena↗

PubMed1980

Reduction of bias in estimating the frequency of recessive genes.

The standard approach to estimating the frequency of a completely recessive autosomal gene is to use the maximum-likelihood estimator (MLE), q = square root q2. Since the expectation oof Q using MLE is systematically less than the true value, this estimator always gives a negatively biased estimate of q. Here we describe the bias associated the MLE over a range of q and N values, explore some of the properties of this estimator, and propose new estimators which reduce the bias. We also describe some of the new estimators' properties, as well as the remaining bias associated with them for varying q and N values. We further propose one of these estimators as the one which most effectively reduces bias over a specific q value range of approximately .005 to .05, and which is less biased than JLE over essentially all q and N values. The proposed estimator also is directly compared with MLE in calculating various available estimates of q, demonstrating the percentage of reduction in bias achieved. This reduction varies from negligible for estimates of q above .3 and N greater than 100, to a 23% reduction in bias for a q value of .09 and an N value of 215.

Gene Frequency↗

PubMed1989

In vitro models of carcinogenesis: expression of recessive genes by chromosomal mutations.

There has been considerable recent interest in the mechanisms by which recessive mutations involving cancer genes may be expressed. We have developed an in vitro model to study this phenomenon in an endogenous autosomal gene in human cells. We have analyzed the molecular structural changes that lead to loss of heterozygosity at the thymidine kinase (tk) locus. The results indicate that expression of a recessive allele frequently occurs by loss of heterozygosity at that locus. Over 90% of spontaneous mutants at the tk locus arose by allele loss. The fraction of induced mutants that arose by this mechanism depended upon the inducing agent. Loss of the active tk allele was often accompanied by loss of linked genetic loci on the long arm of chromosome 17. These results suggest that large-scale chromosomal mutations resulting from events such as deletion or mitotic recombination may be an important mechanism for the expression of activated or mutated recessive genes in human cells. Such recessive mutations could involve oncogenes or other growth regulatory genes important in carcinogenesis.

Cell Division↗

PubMed1977

Genetics of juvenile diabetes mellitus. A recessive gene closely linked to HLA D and with 50 per cent penetrance.

We investigated the genetic predisposition to juvenile diabetes in the families of 31 index cases in relation to the inheritance of the HLA system. The diabetes-predisposing gene was found to be recessive because the diabetic sibs in index cases shared both their HLA genes with a significantly increased frequency. Penetrance was estimated at 50 per cent because half the HLA-identical sibs in index cases were diabetic. These conclusions fit with published observations that the risk to sibs of patients is about 100 per cent, when both parents are normal. In three informative cases of recombination within HLA the predisposing gene traveled with the HLA D segment of the recombinant haplotype. We prepared tables for the computation of risks to relatives, based on the hypothesis of recessivity, HLA linkage and 50 per cent penetrance.

Adolescent↗

PubMed2004

The basis for colorless hemolymph and cocoons in the Y-gene recessive Bombyx mori mutants: a defect in the cellular uptake of carotenoids.

Bombyx mori is an excellent model for the study of carotenoid-binding proteins (CBP). In previous papers, we identified and molecularly characterized a CBP from the Y-gene dominant mutants. In the present study, we attempted to correlate and establish lipid metabolism and distribution in these mutants. When [3H]-triolein was fed to the mutants, typical patterns of uptake of labeled fatty acids from midgut to hemolymph and subsequent delivery to fat body and silk glands were obtained in all mutants. Further analysis of lipid and carotenoid profiles revealed that the yellow coloration in the hemolymph associated with lipophorin is not attributed to a difference in lipophorin concentrations among the mutants, nor to its lipid composition, but rather to its carotenoid content. Lipophorin of the Y+I mutant exhibited the highest concentration of total carotenoids of 55.8 microg/mg lipophorin compared to 3.1 microg/mg in the +Y+I mutant, 1.2 microg/mg in the YI mutant and 0.5 microg/mg in the +YI mutant. Characteristic retention time in HPLC of the different classes of carotenoids of lipophorin identified the presence of lutein as the major chromophore (62-77%), followed by beta-carotenes (22-38%). Although lutein and beta-carotene content of mutants' lipophorin differed significantly, the ratio of lutein to beta-carotene of 3:1 was not different among mutants. Similarly, lipid compositions of mutant silk glands were not significantly different, but carotenoid contents were. The significantly high concentration of lutein in the Y+I mutant silk gland represented more than 160-fold increase compared to +Y+I mutant (p<0.001). In this report, we conclude that lipid metabolism in the mutants is not defected and that the molecular basis for colorless hemolymph and cocoons is a defect in the cellular uptake of lutein associated with the Y-gene recessive mutants.

Animals↗

PubMedDate not supplied

Three recessive genes for congenital osteopetrosis in Norway rat.

In the rat, the autosomal recessive toothless (t1) mutation exhibits an acute form of osteopetrosis. This gene is not an allele of either ia or op that causes respectively, a transitory and acute form of the disease. Comparative radiographic study of t1/t1 and op/op mutants reveals some differences in respect to the size and shape of long bones. In contrast to op/op mutants, homozygous t1/t1 animals failed to respond to either parabiosis or bone marrow transplants.

Alleles↗

PubMed2002

Vestibular dysfunction in the epistatic circler mouse is caused by phenotypic interaction of one recessive gene and three modifier genes.

Vestibular dysfunction is a frequent clinical problem, leading to dizziness and imbalance. Genes play an important role in its etiology, but the genetics are complex and poorly understood. In this study we have analyzed the complex inheritance pattern in the Epistatic circler mouse, which shows circling behavior indicative of vestibular dysfunction in the mouse. This phenotype exists in a proportion of the F2-generation from an intercross between C57L/J and SWR/J mouse strains. Genetic investigation indicates that the circling behavior is caused by a major recessively inherited gene derived from the SWR/J strain (the Ecs-gene) in combination with at least three different modifier genes derived from C57L/J (the Ecl-genes). Genetic mapping made it possible to localize the Ecs-gene to chromosome 14 and the Ecl-genes to chromosome 3, 4, and 13. This study illustrates the feasibility of identifying genes for multifactorial traits in mice.

Animals↗

PubMed1982

Evidence for an autosomal recessive gene regulating the persistence of the insulin response to glucose in man.

The significance of genetic factors for insulin release after glucose infusion was studied in 155 nuclear families of which 59 were control families and 96 had been ascertained through a parent with onset of diabetes after 30 years of age. Fasting insulin and glucose as well as three principal components of the insulin and glucose curves were submitted to path analysis and complex segregation analysis. The three principal components were considered to reflect the magnitude, the degree of response and the persistence of the curves. The genetic heritability of the insulin variables varied between 0.47-0.93 and that of the glucose variables between 0.20-0.54. There were considerable intergenerational differences in the genetic heritability for the persistence of the glucose curve and for the degree of response and persistence of the insulin curve. The cultural heritability was found to be of minor importance, while the non-transmitted sibling environment was large. There was significant evidence for a major locus for the persistence of the insulin curve. The best fit was for a completely recessive autosomal gene with the gene frequency 0.21. The phenotype distribution of this variable showed significant kurtosis which could simulate a major locus. However, the significant evidence for such a locus remained after an analysis using partial quantitation. The diabetics were significantly different from the non-diabetics for all the variables studied, but a complete discrimination between the diabetics and non-diabetics could not be obtained. There was no significant difference between the children of the diabetics and non-diabetics for any of the variables studied.

Adult↗

PubMed1990

The induction of tail malformations in trisomy 16 mouse fetuses heterozygous for the curly tail recessive gene.

The mouse mutant curly tail is thought to be inherited as an autosomal recessive (ct/ct) with incomplete penetrance so that approximately 60% of ct/ct individuals exhibit the curly tail (CT) phenotype. By outcrossing ct/ct with mouse stock carrying specific heterozygous combinations of Robertsonian (Rb) chromosomes, trisomy 16 (Ts16) and Ts19 mouse fetuses (and their chromosomally balanced littermates) were derived which were heterozygous for the ct gene. All of the Ts16 (ct/Rb;Rb) fetuses, studied between days 14-19 gestation had tail malformations, 86% of which were tail flexion defects (TFD) apparently very similar to the curly tail phenotype. Neither Ts19 nor any of the chromosomally balanced (ct/Rb) littermates from both experimental crosses showed any type of tail or other spinal malformation. At the 27-29 somite stage of development, Ts16 (ct/Rb;Rb) fetuses did not show any significant delay in the closure of the posterior neuropore (PNP) compared with their littermate controls, suggesting that the tail malformation observed in Ts16 (ct/Rb;Rb) occur as a result of mechanisms which differ significantly from those thought to be responsible to causing the curly tail malformation.

Animals↗

PubMed1999

Subclinical audiological findings in carriers of recessive genes for deafness.

The existence of subclinical signs in the hearing of carriers of recessive mutations for deafness has aroused much controversy in the literature. The present study comprised 30 carriers of recessive mutations for deafness, and a control group of 30 healthy volunteers, matched for gender and age. All participants underwent a series of hearing tests, including pure-tone audiometry, speech tests, Bekesy audiometry and notch noise tests. The main results were: hearing loss in high frequencies (3000 and 4000 Hz), an elevation of the acoustic reflex threshold, as well as an elevation of the identification of 2000 Hz pure tone in the presence of white noise and notch noise. A notch in the Bekesy audiogram was also identified in several carriers. An interaction was found between gender and the carrier trait in the hearing threshold at 4000 Hz, and in the ipsi- and contralateral acoustic reflex at 500 Hz and 1000 Hz. These subclinical signs may be complementary to DNA research in the investigation of genetic deafness of unknown origin.

Adult↗

PubMed1991

Dominant and recessive genes involved in tumor cell invasion.

The past year has been the discovery and further analysis of several genes and protein products that are critically involved in the generation of invasive and metastatic tumor cells. Like oncogenes and tumor suppressor genes, the genes responsible for invasive and metastatic phenotypes can function in a dominant or recessive fashion. In this review, particular emphasis will be given to the dominantly acting genes encoding the cell adhesion molecule CD44 and the motility factor scatter factor, and the recessively acting genes encoding the cell adhesion molecule E-cadherin and nm23.

Amino Acid Sequence↗

PubMed1986

An Lu(a-b-) phenotype caused by an X-linked recessive gene.

The family of a male Lu(a-b-) propositus whose red cells showed some characteristics of the dominant and some of the recessive type of Lu(a-b-) phenotype was studied. The investigation revealed a third genetic background for this rare phenotype, an X-borne suppressor recessive in effect. The notation proposed is XS1 for the normal gene and XS2 for the suppressor gene which affects the expression of Lutheran and other antigens.

Female↗

PubMed1978

Further study of the X-linked recessive gene hypothesis for inheritance of spatial abilities.

Two measures of spatial ability were administered to 319 undergraduates, 93 parents, and 62 siblings. Although males outperformed females on both tests, the resulting correlational pattern did not conform to the trait pattern hypothesized on the basis of an X-linked recessive trait. Results from a pedigree analysis, however, were in the expected direction. The inclusion of pedigree analyses is urged in future research.

Female↗

PubMed2000

Localization of a recessive gene for North American Indian childhood cirrhosis to chromosome region 16q22-and identification of a shared haplotype.

North American Indian childhood cirrhosis (NAIC, or CIRH1A) is an isolated nonsyndromic form of familial cholestasis reported in Ojibway-Cree children and young adults in northwestern Quebec. The pattern of transmission is consistent with an autosomal recessive mode of inheritance. To map the NAIC locus, we performed a genomewide scan on three DNA pools of samples from 13 patients, 16 unaffected siblings, and 22 parents from five families. Analysis of 333 highly polymorphic markers revealed 3 markers with apparent excess allele sharing among affected individuals. Additional mapping identified a chromosome 16q segment shared by all affected individuals. When the program FASTLINK/LINKAGE was used and a completely penetrant autosomal recessive mode of inheritance was assumed, a maximum LOD score of 4.44 was observed for a recombination fraction of 0, with marker D16S3067. A five-marker haplotype (D16S3067, D16S752, D16S2624, D16S3025, and D16S3106) spanning 4.9 cM was shared by all patients. These results provide significant evidence of linkage for a candidate gene on chromosome 16q22.

Adult↗

PubMed1990

Simulation of Mendelism revisited: the recessive gene for attending medical school.

Much of the recent confusion concerning studies of complex phenotypes such as neuropsychiatric disorders may derive from the inappropriate assumption of simple Mendelian transmission. This has sometimes led to unrealistic expectations regarding the potential benefits of linkage studies. To investigate how Mendelism may be simulated, we collected data on a common familial behavioral trait, attendance at medical school, among the relatives of 249 preclinical medical students. The "risk" of first-degree relatives going to medical school was approximately 61 times that of the general population. Complex segregation analysis carried out under a unified model provided strong evidence of vertical transmission. The results were compatible with transmission of a major effect, and a recessive model provided as satisfactory a fit as a general single-locus model. Moreover, a commonly applied test, allowing the transmission probability parameter (tau 2) to deviate from its Mendelian value, did not give a significant improvement of fit. Only a more general model where all three transmission probabilities (tau 1, tau 2, and tau 3) were unrestricted resulted in a significantly better fit than did the recessive model.

Education↗

PubMed2006

RAPD-based SCAR marker SCA 12 linked to recessive gene conferring resistance to anthracnose in sorghum [Sorghum bicolor (L.) Moench].

Anthracnose, caused by Colletotrichum graminicola, infects all aerial parts of sorghum, Sorghum bicolor (L.) Moench, plants and causes loss of as much as 70%. F(1) and F(2) plants inoculated with local isolates of C. graminicola indicated that resistance to anthracnose in sorghum accession G 73 segregated as a recessive trait in a cross with susceptible cultivar HC 136. To facilitate the use of marker-assisted selection in sorghum breeding programs, a PCR-based specific sequence characterized amplified region (SCAR) marker was developed. A total of 29 resistant and 20 susceptible recombinant inbred lines (RILs) derived from a HC 136 x G 73 cross was used for bulked segregant analysis to identify a RAPD marker closely linked to a gene for resistance to anthracnose. The polymorphism between the parents HC 136 and G 73 was evaluated using 84 random sequence decamer primers. Among these, only 24 primers generated polymorphism. On bulked segregant analysis, primer OPA 12 amplified a unique band of 383 bp only in the resistant parent G 73 and resistant bulk. Segregation analysis of individual RILs showed the marker OPA 12(383) was 6.03 cM from the locus governing resistance to anthracnose. The marker OPA 12(383) was cloned and sequenced. Based on the sequence of cloned RAPD product, a pair of SCAR markers SCA 12-1 and SCA 12-2 was designed using the MacVector program, which specifically amplified this RAPD fragment in resistant parent G 73, resistant bulk and respective RILs. Therefore, it was confirmed that SCAR marker SCA 12 is at the same locus as RAPD marker OPA 12(383) and hence, is linked to the gene for resistance to anthracnose.

Base Sequence↗