Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Heterozygote”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1980

[Intracellular concentration of phenylalanine, tyrosine and alpha-amino butyric acid in 13 homozygotes and 19 heterozygotes for phenylketonuria (PKU) compared with 26 normals (author's transl)].

Intracellular concentrations for phenylalanine, tyrosine, alpha-amino butyric acid and 7 other amino acids (glycine, alanine, valin, cystin, methionine, iso-leucin, leucin) were measured in lymphocytes of 13 homozygotes and 19 heterozygotes for phenylketonuria as well as in lymphocytes of 26 normals. Intracellular concentrations for phenylalanine, tyrosine and alpha-amino butyric acid were significantly higher in homo- and heterozygotes than in normals (p less than 0,001--p less than 0,01). For the other 7 amino acids there were no or only questionable differences. Between homo- and heterozygotes there was no difference in any of the amino acids. Intracellular phenylalanine: tyrosine ratio was essentially the same in all three groups of individuals. There was no correlation between intracellular phenylalanine above or below 10 nmol/10(6) cells and IQ in heterozygotes. The same is true for phenylalanine: tyrosine ratio greater or smaller than 1. In Homozygotes there was no correlation between intracellular phenylalanine and age -- to whom DQ/IQ is correlated. There was no significant difference in intracellular phenylalanine between homozygotes with blood levels above and below 908 mumol/l (15 mg/100 ml) at the time of blood sampling and no correlation between intra- and extra-cellular phenylalanine concentrations. Among the 26 normals there were only 2 with intracellular phenylalanine above 10 nmol/10(6) cells, both showing phenylalanine loading test curves suspicious for heterozygosity. The results are discussed and important functions of the cell wall supposed. An abnormal unknown intracellular metabolite being the real noxious agent could explain the incomparably different degree of brain dysfunction in individuals with equal though elevated intracellular phenylalanine concentrations i.e. homozygotes and heterozygotes for PKU.

Aminobutyrates↗
PubMed1981

Identification of heterozygotes for glycogenosis 2 (acid maltase deficiency).

In 21 obligate and 9 possible heterozygotes for acid maltase deficiency (AMD) (glycogenosis 2, Pompe's disease), different methods of identifying heterozygotes have been studied. Heterozygosity could not be demonstrated by physical examination, serum CPK assays, morphological examination of muscle biopsy (including light-microscopy, histochemistry and electron-microscopy), or by ultrastructural examination of a skin biopsy. Heterozygotes could be identified to a large, but still limited extent, by measuring the acid alpha-glucosidase activity in urine, cultivated fibroblasts, leucocytes, or skeletal muscle. Heterozygotes for the generalized from of AMD could not be distinguished from those for the muscular form. The limitations of heterozygote identification by means of enzyme assays are discussed, and some practical aspects for genetic counselling are mentioned.

Female↗
PubMedDate not supplied

Mutans streptococci, lactobacilli and caries experience in cystic fibrosis homozygotes, heterozygotes and healthy controls.

Mutans streptococci (MS) and lactobacillus (LB) counts (CRT Bacteria chair-side test) were compared and correlated with the respective caries experience (DMF) of cystic fibrosis (CF) homozygotes (n = 20), CF heterozygotes (n = 20) and healthy controls (n = 20). Each group of subjects was divided into two equal age groups: group A <20 years and group B >20 years. No significant differences were found regarding DMF between the three groups. CF heterozygotes had a significantly higher DMF-S than CF homozygotes (p = 0.040). This was also found in age group B (p<0.02), where it also counted for DMF-T (p<0.01). When in age group B, CF heterozygotes and controls were combined as one group, it was found that they had a significantly higher DMF-T (p = 0.031) and DMF-S (p = 0.008) than CF homozygotes. No significant differences in LB counts between the three groups were observed. CF homozygotes and those in age group A had significantly (p = 0.018 and p = 0.015) more low MS counts. LB and MS counts were positive and significantly correlated with DMF-T/-S in CF homozygotes and in the combined group of CF heterozygotes with controls (p< or = 0.05 and < or = 0.001). No correlations between bacterial counts and DMF were observed in CF heterozygotes. It can be concluded that despite the fact that CF homozygotes behave as high caries risk individuals, they did not have significantly more dental decay. More research is required in order to explore salivary, dietary and medication influences.

Adolescent↗
PubMed1992

Male meiosis and gametogenesis in wild house mice (Mus musculus domesticus) from a chromosomal hybrid zone; a comparison between "simple" Robertsonian heterozygotes and homozygotes.

Wild male house mice Mus musculus domesticus were collected from the hybrid zone between the John o'Groats race (2n = 32) and the standard race (2n = 40) in northern Scotland. Meiosis in both homozygotes (2n = 32, 36, and 40) and single Robertsonian heterozygotes (2n = 33, 35, and 37) was found to be orderly. At prophase/metaphase I in heterozygotes, a trivalent was formed from the metacentric and two homologous acrocentrics. At pachytene, this trivalent usually had a single side arm at the position of the centromeres, as a result of nonhomologous pairing of the acrocentrics. This side arm persisted into diplotene. Generally only a single chiasma was formed between each acrocentric and the metacentric. Anaphase I nondisjunction frequencies were estimated as 1.5% for the homozygotes and 2.7% for the heterozygotes. The extent of germ cell death between the pachytene and round spermatid stages was 18% greater in heterozygotes than in homozygotes. Our results concur with previous studies which indicate that single Robertsonian heterozygotes in wild house mice have near-normal fertility.

Animals↗
PubMed1993

Characterization of six patients who are double heterozygotes for familial hypercholesterolemia and familial defective apo B-100.

Familial defective apolipoprotein B-100 (FDB) and familial hypercholesterolemia (FH) are the common causes of monogenic primary hypercholesterolemia. An individual of mixed English and Afrikaner descent with both FDB and the FH Afrikaner-1 low-density lipoprotein receptor mutation was identified in our laboratory. Subsequent analysis of her extended family revealed the presence of heterozygotes for either FH Afrikaner-1, FH Afrikaner-2, or FDB as well as five additional double heterozygotes for FH Afrikaner-1 and FDB and one "complex" heterozygote with all three mutations. The hypercholesterolemic and clinical features of the pure FDB subjects were similar to those of the pure FH heterozygotes. The double heterozygotes with both FH and FDB have lipid levels and clinical features that are intermediate in severity between heterozygous and homozygous FH.

Adolescent↗
PubMed2000

Age and residual cholesterol efflux affect HDL cholesterol levels and coronary artery disease in ABCA1 heterozygotes.

We and others have recently identified mutations in the ABCA1 gene as the underlying cause of Tangier disease (TD) and of a dominantly inherited form of familial hypoalphalipoproteinemia (FHA) associated with reduced cholesterol efflux. We have now identified 13 ABCA1 mutations in 11 families (five TD, six FHA) and have examined the phenotypes of 77 individuals heterozygous for mutations in the ABCA1 gene. ABCA1 heterozygotes have decreased HDL cholesterol (HDL-C) and increased triglycerides. Age is an important modifier of the phenotype in heterozygotes, with a higher proportion of heterozygotes aged 30-70 years having HDL-C greater than the fifth percentile for age and sex compared with carriers less than 30 years of age. Levels of cholesterol efflux are highly correlated with HDL-C levels, accounting for 82% of its variation. Each 8% change in ABCA1-mediated efflux is predicted to be associated with a 0.1 mmol/l change in HDL-C. ABCA1 heterozygotes display a greater than threefold increase in the frequency of coronary artery disease (CAD), with earlier onset than unaffected family members. CAD is more frequent in those heterozygotes with lower cholesterol efflux values. These data provide direct evidence that impairment of cholesterol efflux and consequently reverse cholesterol transport is associated with reduced plasma HDL-C levels and increased risk of CAD.

ATP Binding Cassette Transporter 1↗
PubMed2000

Cellular cholesterol efflux in heterozygotes for tangier disease is markedly reduced and correlates with high density lipoprotein cholesterol concentration and particle size.

Tangier disease (TD), caused by mutations in the ATP-binding cassette 1 (ABC-1) gene, is a rare genetic disorder characterized by severe deficiency of high density lipoproteins (HDL) in the plasma, hypercatabolism of HDL, and defective apolipoprotein (apo)-mediated cellular cholesterol efflux. In the present study, we assessed plasma lipid concentrations, HDL particle size and subspecies, and cellular cholesterol efflux in 9 TD heterozygotes from a kindred in which the proband was homozygous for an A-->C missense mutation at nucleotide 5338 of the ABC-1 transcript. Relative to age- and gender-matched controls from the Framingham Offspring Study (FOS), TD heterozygotes had significant reductions (P < 0.000) in HDL-C (-54% female; -40% male) and apoA-I (-33% female; -37% male) concentrations, as well as significantly less cholesterol (-68% female; -58% male) distributed in the largest HDL subclasses, H5 and H4. Consequently, HDL particle size (nm) was significantly smaller (P < 0.000) in TD heterozygotes (8.6 +/- 0.6 female; 8.7 +/- 0.1 male) relative to FOS controls (9.4 +/- 0.4 female; 9.0 +/- 0.3 male). Further studies demonstrated that apoA-I-mediated cellular cholesterol efflux in TD heterozygotes was essentially half that of controls (11 +/- 2 vs. 20 +/- 3% of total [(3)H]cholesterol, P < 0. 001), with strong correlations observed between cholesterol efflux and both HDL-C level (r = 0.600) and particle size (r = 0.680). In summary, our data demonstrate that apolipoprotein-mediated cholesterol efflux is aberrant in TD heterozygotes, as it is in homozygotes. This finding, along with the associations observed between HDL-C concentration, HDL particle size, and cholesterol efflux, supports the concept that plasma HDL-C levels are regulated, in part, by cholesterol efflux, which in turn influences HDL particle size and, ultimately, HDL apoA-I catabolism.

ATP Binding Cassette Transporter 1↗
PubMed1998

[Genetic diagnosis of alpha and beta thalassemia dual heterozygote].

OBJECTIVE: To perform genetic diagnosis of alpha and beta thalassemia dual heterozygotes. METHODS: PCR and beta-thalassemia allele specific oligonucleotide probe/reverse dot blot(ASO/RDB) techniques were used. RESULTS: Six cases of suspected alpha-thalassemia-1 and beta-thalassemia dual heterozygotes were found in genetic counseling and prenatal diagnosis. On genetic diagnosis, they were all Southeast Asia(SEA) type of alpha-thalassemia-1 and beta-thalassemia (--SEA/alpha alpha, beta T/beta A) dual heterozygotes. Out of them, 3 cases were alpha-thalassemia-1 and beta 41-42 (-TCTT), 2 were alpha-thalassemia-1 and beta-28(A-->T) and 1 was alpha-thalassemia-1 and beta IVS-II-654(C-->T) double heterozygotes. CONCLUSION: The detection of thalassemia dual heterozygotes facilitates the prenatal diagnosis with more precision.

Adult↗
PubMedDate not supplied

Is hereditary hemochromatosis a balanced polymorphism: an analysis of family size among hemochromatosis heterozygotes.

BACKGROUND/AIMS: Hereditary hemochromatosis (HH) has a homozygote frequency of 0.5% and a heterozygote frequency of 13%, which suggests that hemochromatosis might be a balanced polymorphism. Evidence for this was sought by assessing reproductive success among hemochromatosis heterozygotes through determining their family size and incidence of miscarriage when compared to nongene carriers. METHODOLOGY: A cohort was defined in which the exposure variable was heterozygosity for hereditary hemochromatosis. Heterozygotes were identified by mailing individuals homozygous for hereditary hemochromatosis questionnaires concerning the number of siblings born alive and the number of miscarriages suffered by their mothers (predominantly heterozygotes, or HHH). Spouses of the hereditary hemochromatosis homozygotes were asked to complete accompanying questionnaires concerning their mothers (CONT). RESULTS: Five hundred and ninety-six responses were received from hereditary hemochromatosis homozygotes and 532 responses from spouses of the hereditary hemochromatosis homozygote respondents. The mothers of the hereditary hemochromatosis homozygote respondents had a mean family size of 3.699. The mothers of the unexposed spouse controls a mean family size of 3.639 (P = 0.66 by ANOVA). One hundred and twenty-three of the HHH mothers suffered a total of 201 miscarriages, whereas 94 of the CONT mothers suffered 147 miscarriages (P = 0.38 by ANOVA). CONCLUSIONS: In this cohort, no evidence among hemochromatosis heterozygotes of reproductive advantage and therefore heterozygous advantage by this mechanism was seen.

Abortion, Spontaneous↗
PubMed1991

[Symptomatic adrenoleukodystrophy heterozygote with fluctuated neurological symptoms--a case report].

We report a patient with symptomatic adrenoleukodystrophy (ALD) heterozygote, a 57-year-old female, who manifested fluctuated neurological symptoms. She is a mother of the patient with adrenoleukomyeloneuropathy associated with hypoparathyroidism and cerebral calcification. The heterozygote of ALD was diagnosed by elevated levels of very long chain fatty acids in her plasma and erythrocyte membranes. At age 51, she had a disturbance of consciousness, which subsided two months later. Neurologically, bilateral pyramidal tract signs were noted. CT revealed low-density areas in the white matter neighboring the bilateral anterior horns of lateral ventricles and small calcification in the basal ganglia. Four years later, her neurological manifestations including gait disturbance and mental deterioration subacutely progressed. MRI (T2-weighted image) showed diffuse high intensity areas in the cerebral white matter. Adrenal insufficiency, hypoparathyroidism and peripheral neuropathy were not detected. It has been reported that some ALD heterozygotes developed neurological symptoms, which resembled those of the patients with adrenomyeloneuropathy. The presented patient manifested neurological symptoms with fluctuation, which was not common clinical course in the heterozygotes of ALD. On the differential diagnosis of neurological diseases such as multiple sclerosis, cerebrovascular disease or other cerebral white matter diseases, it is important to consider the possibility of ALD heterozygotes.

Adrenoleukodystrophy↗
PubMed1990

Immunological pattern in heterozygote beta thalassemic subjects.

In heterozygote beta-thalassemic subjects in a higher incidence of infectious diseases and of liver diseases with progression toward chronic hepatitis has been assessed. This predisposition has been suggested as being related to some immunological defects and to an altered immunological reactivity in thalassemia trait carriers. In order to evaluate whether there is a real deficiency of some humoral and cellular parameters in healthy heterozygote beta-thalassemic subjects, 128 symptom-free volunteers have been studied: 40 were heterozygote beta thalassemia carriers and 88 were normal subjects. In both groups there was no difference in: number and percentage of total lymphocytes, gamma globulins, immunoglobulins A and M, number and percentage of CD21, CD3, CD4, CD8, number of OKla*1, CD4/CD8 rations and lymphocytes' ability to respond to phytohemagglutinin. The values of immunoglobulins G and percentages of OKla*1 were found to be higher only in heterozygote beta thalassemic subjects; however, the number of CD2 in these subjects was lower. The result of the present study seems to indicate there is not significant difference between heterozygote beta thalassemic carriers and normal subjects in the more usual humoral and cellular immunological parameters.

Adult↗
PubMed1982

[Anemia 2,3-DPG and tissue oxygenation in beta-thalassemia heterozygotes].

The levels of 2,3-DPG and the value of P50 were determined in unselected, clinically healthy, typical beta-thalassemia heterozygotes and normal controls. Values of 2,3-DPG in the heterozygotes are significantly elevated compared to normals (when expressed per gram of hemoglobin or per volume of red cells) and much higher than their mild hemoglobin deficit would explain; they are elevated even in selected heterozygotes presenting normal hemoglobins levels. These 2,3-DPG values, when expressed per number of erythrocytes, are within normal limits. In parallel, oxygen affinity is lower, as the P50 value is displaced to the right by 2 mmHg above the normal mean, thus assuring adequate tissue oxygenation. The findings suggest that the high 2,3-DPG values of the beta-thalassemia heterozygotes are not determined solely by anemic hypoxia; it is more likely that the microcytic erythrocytosis of heterozygous beta-thalassemia is the cause of this increase. The resulting lower oxygen affinity leads to a decreased stimulation of erythropoiesis and hence to its regulation at lower hemoglobin levels. Accordingly we suggest that the beta-thalassemia trait is a pseudo-anemia, because it is unlikely that these heterozygotes are unable to reach normal hemoglobin values by increasing erythrocyte output.

2,3-Diphosphoglycerate↗
PubMed1993

[Behavior of pachytene chromosomes in male mice heterozygotic for various translocations (Rb(8,17), T(16,17)43H)].

The electron microscopic analysis of synaptonemal complexes of the Robertsonian translocation heterozygotes (Rb/T) and heterozygotes of the reciprocal translocation (Rb(8, 17)/T(16, 17) 43H revealed three types of translocation configurations (TC). The observed TC were subdivided into three types according to the manner of synapsis: 1) full synapsis of homologues forming trivalent with interstitial centromere in 15%; 2) the centromeric asynapsis (8 and 17-16 chromosomes forming trivalent with the extension region of asynapsis and breakpoint of the reciprocal translocation on chromosome 17 in 70%; 3) centromeric asynapsis (only single chromosome 17-16 of trivalent, when the break point of reciprocal translocation and the absence of centromeric asynapsis of another chromosome 8 formed trivalent in 15%). The frequency of association between trivalents and the XY bivalents is 20% and close proximity is 15% for heterozygotes Rb/T. Which are fertile, while in the sterile heterozygotes Rb(8, 17)/T(16, 17) 43H it is 45% for association and 15% close proximity (total 60%). These data show the significant differences in the contact of translocation configurations with the XY bivalents of fertile heterozygotes, in comparison with the sterile. Thus, it is shown that the chromosome pairing of fertile and sterile mice is clearly distinguished.

Animals↗
PubMed1995

Response of dermal fibroblast cultures from patients with unusually severe responses to radiotherapy and from ataxia telangiectasia heterozygotes to fractionated radiation.

We examined the cytotoxic effects of radiation delivered in daily fractions at clinically relevant doses in plateau phase cultures of skin fibroblast cell strains derived from ataxia telangiectasia (AT) heterozygotes, patients with unusually sensitive responses to radiotherapy, apparently normal patients, and cell bank controls. A gradual linear reduction in surviving fraction versus total dose was observed in the control group, comprised of apparently normal individuals and one patient with a normal clinical response to radiotherapy, after exposure to daily fractions of 2.0 Gy. There was a much steeper decline in surviving fraction among the AT heterozygotes and the group with sensitive responses to radiotherapy, such that after six daily fractions of 2.0 Gy (12 Gy total dose), the mean surviving fraction of the control group was significantly different from that of the AT heterozygotes (P = 0.0009) and that of the patients with unusually sensitive responses to radiotherapy (P = 0.0002). We propose that this assay may be a useful means of identifying cell strains from AT heterozygotes. Based on these results, the hypothesis is discussed that patients who suffer unusually sensitive clinical reactions to radiotherapy may be AT heterozygotes.

Adolescent↗
PubMed1992

Heterozygote detection through bleomycin-induced G2 chromatid breakage in dyskeratosis congenita families.

We determined the mean number of chromatid breaks per cell (b/c) in the bleomycin-treated lymphocytes of 10 patients with dyskeratosis congenita (DC) and 26 of their relatives to ascertain whether bleomycin sensitivity would distinguish DC heterozygotes from normal individuals. We observed a significantly higher mean number of chromatid b/c in DC patients and obligate heterozygotes (patients versus controls, p less than 0.0001; heterozygotes versus controls, p = 0.0076, Mann-Whitney rank-sum test). Unequivocal heterozygote detection was not possible owing to overlap of the b/c values of patients, heterozygotes, and controls, but our findings provided strong evidence of a link between autosomal recessive as well as X-linked recessive DC mutations and bleomycin sensitivity in homozygous, hemizygous, and heterozygous individuals.

Adolescent↗
PubMed1981

The occurrence and identification of alpha-thalassemia-2 among hemoglobin S heterozygotes.

The in-vitro synthesis of hemoglobin (Hb) chains was studied among 60 Hb S heterozygotes (AS) having different quantities of Hb S, including five with an associated alpha-chain heterozygosity (ASAG). Hematologic values and hemoglobin composition were studied in these cases and in 15 other ASAG heterozygotes. The percentages of Hb S (which fell between 27% and 42%) and the mean corpuscular volume values correlated directly with the alpha/non-alpha values, confirming previous suggestions (Huisman, Hemoglobin 1:349, 1977) that the concomitant occurrence of an alpha-thalassemia-2 heterozygosity (alpha alpha(0)/alpha alpha; beta/beta(S)) or homozygosity (alpha(0) alpha/alpha(0) alpha; beta/beta(S)) resulted in intermediate or lower levels of Hb S compared with Hb S heterozygotes having four active alpha-chain genes (alpha alpha/alpha alpha; beta/beta(S)). Among ASAG heterozygotes, the occurrence of low (about 25%), intermediate (about 33%), or high (about 45%) proportions of an alpha-chain variant resulting from a variability in the number of active alpha-chain genes due to alpha-thal-2 coincided with high (39%), intermediate (34%), or low (28%) levels of Hb S, respectively. However, the overlap of biosynthetic data between Hb S heterozygotes with four, three, or two active alpha-chain genes prevents a reliable diagnosis in individual cases.

Anemia, Sickle Cell↗
PubMed1982

Fabry disease: detection of heterozygotes by examination of glycolipids in urinary sediment.

Fabry disease is an X-linked sphingolipid disorder that is manifest clinically as a disease of nerves, kidneys, and blood vessels. Precise identification of Fabry heterozygotes is essential for genetic counseling. Heterozygote detection by enzyme assay does not consistently distinguish them from unaffected females. We describe a method for Fabry heterozygote detection, based on quantitation of urinary sediment glycolipids by high-performance liquid chromatography. In specimens from 12 Fabry heterozygotes, the total glycolipid fraction was increased (10 to 100-fold) and trihexosyl ceramide (CTH) was 2- to 70-fold times normal. Digalactosyl ceramide (Digal-Cer), which is normally present in trace amounts in urine, was also increased. The ratio of CTH and Digal-Cer to hydroxy fatty acid glucosyl ceramide was increased and seemed to be characteristic of Fabry disease. This method provides rapid and accurate detection of Fabry heterozygotes.

Adolescent↗
PubMed2006

Levels of gamma-H2AX Foci after low-dose-rate irradiation reveal a DNA DSB rejoining defect in cells from human ATM heterozygotes in two at families and in another apparently normal individual.

We have investigated the use of the gamma-H2AX assay, reflecting the presence of DNA double-strand breaks, as a possible means for identifying individuals who are mildly hypersensitive to ionizing radiation, such as some ATM heterozygotes. We compared levels of gamma-H2AX foci after irradiation in cells from six apparently normal individuals as well as from individuals from two separate AT families including the proband, mother, father and three unaffected siblings in each family. After a 1-Gy single acute (high-dose-rate) gamma-ray dose delivered to noncycling contact-inhibited monolayers of cells, clear differences were seen between samples from normal individuals (ATM(+/+)) and probands (ATM(-/-)) at nearly all sampling times after irradiation, but no clear distinctions were seen for cells from normal compared to obligate heterozygotes (ATM(+/-)). In contrast, after 24 h of continuous irradiation at a dose rate of 10 cGy/h, appreciable differences in numbers of foci per cell were observed for cells from individuals for all the known ATM genotypes compared with controls. Four unaffected siblings had mean numbers of foci per cell similar to that for the obligate heterozygotes, whereas the other two had mean values similar to that for normal controls. We determined independently that those siblings with mean numbers of foci per cell in the range of ATM heterozygotes carried the mutant allele, while both siblings with a normal number of foci per cell after irradiation had normal alleles. A more limited set of experiments using lymphoblastoid cell strains in the low-dose-rate assay also revealed distinct differences for normal compared to ATM heterozygotes from the same families and opens the possibility of using peripheral blood lymphocytes as a more suitable material for an assay to detect mild hypersensitivities to radiation among individuals.

Ataxia Telangiectasia↗