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PubMed1991

Percentile curves for red cell indices of beta zero-thalassaemia heterozygotes in infancy and childhood.

This paper describes the percentile curves for red blood cell (RBC) count, Hb, mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values of beta zero-thalassaemia heterozygotes during infancy, childhood and adolescence. Hb values were about 2 g/dl below those of normal controls with a progressive increase with age paralleling the normal developmental trend. The Hb increase with age was due to a progressive rise in the Hb content per cell, the number of RBC remaining nearly constant. MCV and MCH values also increased with age with a pattern parallel to normal control. Because of the high prevalence of alpha-thalassaemia in the Sardinian population, to which all the subjects investigated belong, the 3rd MCH-MCV percentile curves of normal overlap the 97th curve of beta-thalassaemia heterozygotes. The HbA2 levels, however, were always increased as compared to normal. These results confirm in children than screening for heterozygous beta-thalassaemia in populations with a high incidence of alpha and beta-thalassaemia by MCV-MCH determination may overlook a sizeable proportion of beta-thalassaemia carriers. The knowledge of the extent of variation of RBC indices of beta-thalassaemia heterozygotes during infancy, childhood and adolescence, is very useful for the evaluation of a child presenting with a mild microcytic anaemia.

Adolescent↗
PubMed2000

Body proportions in Fanconi anemia heterozygotes.

To study the anthropometric ratios in parents (heterozygotes) of children with Fanconi anemia. The study was carried out in the Department of Hematology, Institute of Child Health & Hospital for Children, Chennai. Parents of children with Fanconi anemia were the subjects of the study. Applying standard instruments and methods, various body measurements were recorded. 31 fathers and 37 mothers were included in the study. A hundred male and female controls of the same ethnic group were also studied for the same parameters. The ratios were calculated and statistically analyzed. It was observed that fathers (male heterozygotes) had shorter forearms, the ratio of upper arm: forearm was significantly increased compared to male controls. In mothers (female heterozygotes) the inter-pupillary distance was increased, the ratio of head circumference to inter-pupillary distance was decreased compared to female controls.

Anthropometry↗
PubMed2000

[Liver changes in heterozygote alpha 1-antitrypsin deficiency PiZ].

Whether heterozygotes with alpha-1-antitrypsin (AAT) deficiency type PiZ bear an increased risk for chronic liver disease is controversial. On the basis of liver tissue from 1,030 autopsies (autopsy series), 1,847 biopsies (biopsy series) and 317 primary liver carcinomas (tumor series), we analysed the effect of heterozygous state PiZ for the development of liver diseases. The PiZ status was screened immunohistochemically and verified in selected cases by SSCP analysis and by sequencing DNA extracted from paraffin embedded tissue. The PiZ frequency in the biopsy series (3.4%) and tumor series (5.99%) was significantly higher than in the autopsy series (1.8%). Hepatic PiZ deposits in heterozygotes sometimes were as extensive as in homozygotes. The amount of PiZ deposits correlated positively with the inflammatory activity and stage of fibrosis, as well as with the age of patients. Patients with concurrent liver disease such as hepatitis and alcoholic liver disease showed significantly higher scores of inflammatory activity, stage of fibrosis and amount of PiZ deposits than those without additional liver disease. Cholangiocarcinomas and combined hepato-cholangiocarcinomas were seen significantly more frequently in patients with PiZ-associated liver carcinoma than in genetic healthy individuals (p = 0.004). Three out of 19 PiZ-associated liver carcinomas had developed in cirrhotic liver tissue. Heterozygotes of type PiZ have an enhanced risk for chronic liver disease including primary liver carcinoma. PiZ-associated liver diseases will become clinically manifest in middle or old aged adults. Rarely this genetic defect causes liver cirrhosis even without concurrent liver disease. PiZ-associated liver carcinomas are frequently characterized by cholangiocellular differentiation and may develop often in non-cirrhotic liver tissue. Immunohistochemistry is a specific method to detect hepatic PiZ deposits.

Adult↗
PubMed1996

Ataxia telangiectasia heterozygotes and patients display increased fluidity and decrease in contents of sulfhydryl groups in red blood cell membranes.

In red blood cell membranes of ataxia telangiectasia mutated (ATM) homozygotes and heterozygotes, decreased values of the corrected fluorescence anisotropy and the anisotropy parameter were found, indicating increased fluidity and decreased microviscosity, respectively. These changes in membranes were accompanied by a decrease in SH-groups and an increase in malondialdehyde (MDA) contents. The content of MDA both in homozygotes and in heterozygotes exceeded roughly threefold the respective control values. Decreased content of GSH in red blood cells was found only in ATM homozygotes. The change most specific for the ATM gene appears to be the increase in fluidity, since only this parameter displays the proportionally greater changes in ATM homozygotes compared to ATM heterozygotes. The observations presented here may indicate that the ATM gene is expressed in precursors of red blood cells and deficiency of normal AT gene function may produce the changes which persist in circulating cells.

Ataxia Telangiectasia↗
PubMed1977

Human hexosaminidase isozymes: chromatographic separation as an aid to heterozygote identification.

The correct identification of Tay-Sachs heterozygotes requires a reliable procedure for separation and quantiation of the hexosaminidase isozymes. The most commonly employed method involves thermal inactivation of the heat labile hexosaminidase A assay of residual enzyme activity. This procedure, however, consistently yields a significantly lower absolute and relative activity of hexosaminidase A and a higher activity of the thermostable components (B and I) in comparison with the results obtained by DEAE-cellulose chromatography. DEAE-cellulose chromatographic separation of the hexosaminidase isozymes in serum following thermal inactivation reveals the presence of relative and absolute increase in the activity of the B and I components in addition to loss of the heat-labile A isozyme. Because the conversion of hexosaminidase A into thermostable forms by heating may vary according to the conditions employed, the thermal inactivation procedure may lead to ambiguity in heterozygote identification. This difficulty can be minimized by fractionation of the hexosaminidase isozymes by DEAE-cellulose chromatography followed by assay of the individual components. In addition to the Tay-Sachs carrier state, other conditions can alter the distribution of the hexosaminidase isozymes in tissues and body fluids. For example in serum of patients with juvenile diabetes mellitus there is a characteristic elevation of hexosaminidase B and less consistently, of hexosaminidase A. Since the activity of hexosaminidase A in serum of diabetics fractionated by ion exchange chromatography is at least as high as the activity in serum of healthy non-carriers, patients with diabetes can be easily differentiated from Tay-Sachs heterozygotes. Similarly, the distribution of the hexosaminidase isozymes in serum is altered during pregnancy, where there is usually a significant rise in hexosaminidase A and I (P). However, during pregnancy activities of hexosaminidase A and I in serum of obligate Tay-Sachs carriers are only 50% of the values observed in non-carriers at comparable gestational periods. Since the absolute activities of hexosaminidase A in serum of pregnant carriers obtained by ion exchange chromatography do not overlap with the activities in serum of non-carrier pregnant women at comparable gestational periods, this method has obvious advantages for identification of pregnancies where the fetus may be at risk for Tay-Sachs disease.

Adolescent↗
PubMed1980

Assay of the beta-glucosidase activity with natural labelled and artificial substrates in leukocytes from homozygotes and heterozygotes with the Norrbottnian type (Type 3) of Gaucher disease.

Leukocytes were isolated from 14 patients (7 males and 7 females ) with Gaucher disease of the Norrbottnian type (Type 3), 32 obligate heterozygotes (16 males and 16 females) for this disease and 20 controls (10 males and 10 females). After collection, the cells were transported in dry ice to the laboratory, where they were assayed. The assays were repeated after the cells had been stored for 12 months. beta-Glucosidase activity was assayed with D-[glucose-U-14C]glucosylceramide at pH 5.8 with Cutscum-Na-cholate as a detergent and 4-methylumbelliferyl-beta-glucoside at pH 4.1 with Triton-Na-taurocholate as a detergent. The activities of two marker enzymes, 4-methylumbelliferyl-beta-galactosidase and N-acetyl-beta-glucosaminidase, were assayed in aliquots of the same leukocyte samples. The activity of beta-galactosidase remained constant during storage, N-acetyl-beta-glucosaminidase increased, while beta-glucosidase decreased as assayed with the natural as well as with the artificial substrate. beta-Glucosidase activity was significantly lower in the female than in male controls and heterozygotes. When assayed with natural substrate beta-glucosidase activity in leukocytes from the male patients was 6--12% of the control mean value and 10--15% in those from the female patients. The corresponding figures found when the artificial substrate was used were 15--30% and 22--45%. The values for the heterozygotes were respectively 42--68% and 34--79% with the natural substrate, and 33--82% and 51--109% with the artificial substrate. No correlation was found between the age of the patient and the beta-glucosidase activity.

Acetylglucosamine↗
PubMed1986

Metabolic conversion of L-[U-14C]phenylalanine to respiratory 14CO2 in healthy subjects, phenylketonuria heterozygotes and classic phenylketonurics.

Ten healthy volunteers, 12 classic phenylketonuria (PKU) heterozygotes, and 5 classic phenylketonurics have been loaded orally with a mixture of 5 microCi of L-[U-14C]phenylalanine plus 25 mg/kg of L-[2H5]phenylalanine. For 3 h thereafter, carbon-14 activity in expired air and total carbon dioxide were measured continuously and the levels of L-phenylalanine and L-tyrosine in plasma were determined in six blood samples. After 3 h, 15.1 +/- 2.1% of the applied dose of radioactivity was recovered in the expired air of the healthy subjects, compared to 10.1 +/- 2.2% for PKU heterozygotes and 0.32 +/- 0.18% for classic phenylketonurics. The integrated activity expired provides a discrimination between normals and PKU heterozygotes with a classification error of about 13% compared to an error of about 9% based on the fasting L-phenylalanine over L-tyrosine ratio. A combination of these two parameters in a two-dimensional discriminatory analysis reduces the classification error to less than 1%. An intraindividual correlation between the absolute activity expired and the formation of L-[2H4]tyrosine formed is shown, confirming that ring hydroxylation of L-phenylalanine to L-tyrosine is mandatory in the catabolism of L-phenylalanine to carbon dioxide.

Breath Tests↗
PubMed1996

Molecular and biochemical approaches in the identification of heterozygotes for homocystinuria.

We compared biochemical and molecular methods for the identification of heterozygous carriers of mutations in the cystathionine beta-synthase (CBS) gene. Eleven relatives of seven unrelated patients with homocystinuria due to homozygous CBS deficiency and controls were studied with respect to total homocysteine concentrations before and after methionine loading. In addition, we determined CBS activity in cultured skin fibroblasts and tested for the presence of five known mutations by a PCR-based method in these seven patients, their relatives and controls. The results demonstrate that measurement of homocysteine after methionine loading and assay of CBS enzyme activity in cultured fibroblasts identify most but not all heterozygotes. There was significant correlation between homocysteine concentrations and CBS activities only after methionine loading (r = 0.12, 0.48, 0.48 and 0.50 at 0, 4, 6 and 8 h, respectively). Among the homozygous patients, molecular approaches identified five T833C and two G919A mutations out of 14 independent alleles, confirming the studies of others that these represent the two most prevalent mutations. In addition, we found that three of six heterozygotes with the T833 C allele had post-methionine loading homocysteine levels which overlapped with controls and of the other three, one (as well as an obligate heterozygote who did not carry any of the five mutant alleles tested) had CBS activity comparable to that of controls. These findings demonstrate that genotyping is useful as an adjunctive method for the diagnosis of the heterozygous carrier state of CBS deficiency.

Adolescent↗
PubMed1993

Manifesting heterozygotes in McArdle's disease: clinical, morphological and biochemical studies in a family.

We report a family with McArdle's disease with several affected individuals in two generations. This unusual pedigree for an autosomal recessive disease is explained by the existence of manifesting heterozygotes in the maternal line. The presence of symptoms in heterozygotes seems to be due to a decrease in myophosphorylase activity below a critical threshold, ranging between 30% and 45% of normal mean value. The occurrence of several manifesting heterozygotes in the maternal line only can be explained by compound heterozygosity of a defective allele and a pseudodeficient allele for myophosphorylase, or by a genetic factor which regulates the phenotypic expression of the gene.

Adolescent↗
PubMed1987

Reduction of neutral gene flow due to the partial sterility of heterozygotes for a linked chromosome mutation.

The effect of linkage between a chromosome mutation producing partially sterile heterozygotes and a neutral locus in reducing the gene flow at the neutral locus is studied using a two-population deterministic model. Chromosome mutations are more efficient in reducing gene flow with low migration rates than with high ones. The interaction between high values of partial heterozygote sterility and low recombination rates can produce, in the low migration pattern, a drastic reduction of gene flow. Nevertheless, since only chromosome mutations with low values of partial heterozygote sterility are likely to be involved in chromosomal speciation, a significant reduction of gene flow will probably occur only for a very limited part of the genome. Therefore, a single chromosome mutation is unlikely to play a primary role in speciation.

Biological Evolution↗
PubMed1982

Detection of triethylenemelamine-induced translocation heterozygotes in CD-1 mice: fertility and cytological methods.

A study was conducted to determine the extent to which translocation carriers can be missed in the heritable translocation test. CD-1 male mice were treated with the mutagen triethylenemelamine and bred to untreated females and male progeny were subjected to fertility and cytogenetic analyses. Fertility testing involved mating 1 male to 3 virgin females and subjecting the females to uterine analysis. The males were classified as having normal or reduced fertility according to the number of live implants produced by the females. The cytogenetic analysis involved scoring 25 primary spermatocytes per mouse for translocation multivalents. A total of 103 male progeny were analyzed. Evaluation of fertility and cytogenetic data confirmed the presence of 18 translocation heterozygotes among the male progeny. On the basis of fertility testing, 1 translocation heterozygote was classified as normal (false negative) based on the production of 11 or more live implants by at least 1 mated female. On the basis of cytogenetic analysis of 25 cells per mouse, 1 partially sterile male was classified as normal (false negative); however, analysis of additional cells showed that this mouse was a translocation heterozygote. The study demonstrates the importance of evaluating fertility and cytogenetic criteria to minimize the extent of misclassification in conducting a heritable translocation test.

Animals↗
PubMed1989

An increased risk of insulin-dependent diabetes mellitus (IDDM) among HLA-DR4,DQw8/DRw8,DQw4 heterozygotes.

Serological HLA typing of 92 insulin-dependent diabetes mellitus (IDDM) patients and 300 healthy controls was performed by the immunomagnetic typing technique. We found an increased risk of IDDM among DR4/w8 heterozygotes, similar to that seen for DR3/4 heterozygotes. The DQ alleles of these DR4/w8 patients were therefore established. When hybridized with a cDNA DQB probe, BamHI-digested DNA from eight out of the nine DR4/w8 patients revealed only one single 10.8-kb DQB1-specific fragment typical of DQw4 and DQw8. DNA from all DR4/w8 patients also hybridized to an oligonucleotide probe corresponding to amino acids (aa) 23-30 of the beta chain of DQw8. However, using the oligonucleotide probe, the staining intensity was found to be only half of that seen when DNA from DQw8 homozygotes was used instead, suggesting that the eight DR4/w8 patients had DQw8 in a single dose and carried the DQw4 allele at the DRw8 haplotype. Therefore, eight of nine DR4/w8 IDDM patients seemed to be DR4,DQw8/DRw8,DQw4, which, thus, may be associated with susceptibility to develop IDDM. One common explanation of IDDM susceptibility for DR4,DQw8/DRw8,DQw4 and DR3,DQw2/DR4,DQw8 heterozygotes may be that they share similar DQ alpha beta epitopes encoded by DQA and DQB genes in trans.

Adolescent↗
PubMed1983

Cold stress and congenital adrenal hyperplasia heterozygotes.

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is common in certain regions of the world characterised by cold winters. The persistence of this potentially lethal recessively inherited disease suggests that an evolutionary advantage is conferred upon the partially affected heterozygotes. Profound hypothermia following acute cold exposure in normal subjects carries a considerable mortality especially from cardiac arrhythmias and dehydration. A hypothesis is proposed to suggest that the incomplete block at the 21-hydroxylase step of steroid biosynthesis decreases stress-induced steroid responses, especially in the younger heterozygote and clinically non-salt-losing homozygote; glucocorticoid and mineralocorticoid insufficiency reduces the severity of cold-induced water diuresis; prevention of severe dehydration contributes towards the ability to survive profound hypothermia. Studies into the salt and water metabolism of the congenital adrenal hyperplasia heterozygote at various ages as well as examination of antidiuretic hormone and steroid hormone interactions upon the renal tubule in cold-exposed normal individuals are merited.

Adrenal Cortex Hormones↗
PubMed1991

The cystic fibrosis heterozygote--advantage in surviving cholera?

Cystic fibrosis (CF) is the most common fatal genetic disorder of caucasians. While it has been hypothesized that there is a CF heterozygote advantage which allowed the gene to achieve such high prevalence, the nature of that advantage remains a mystery. The recent identification and sequencing of the CF gene has increased the probability that the CF heterozygote advantage will be discovered. In this hypothesis we review the information which is known about the selection of the CF mutation and its cellular consequences, and present evidence which suggests that resistance to cholera may have been the environmental factor which selected CF heterozygotes over their 'normal' homozygote cohort. Future lines of experimentation and possible clinical applicability to therapy of secretory diarrhea are presented.

Chloride Channels↗
PubMedDate not supplied

Compound heterozygote states for Hb C/Hb Malay and Hb C/Hb E in pregnancy: a molecular and hematological analysis.

Hemoglobin (Hb) C (alpha2beta(2)6Glu-Lys) is a variant Hb found mainly in West Africa where individuals carrying both Hb C and Hb S (alpha2beta(2)6Glu-Val) usually have a disease similar to sickle cell disease. The Hb C molecule has reduced solubility leading to crystal formation and hemolytic anemia. We report a hitherto undescribed interaction of Hb C and Hb Malay (alpha2beta(2)19Asn-Ser) in a Thai individual. She was a 24-year-old pregnant woman with moderate anemia who had the following hematologic data; Hb 8.9 g/dl, Hct 30.0%, MCV 81.0 fl, MCH 24.1 pg, MCHC 29.7 g/dl, RDW 17.1% and instead of Hb crystal a marked number of target cell in peripheral blood was observed. Hb analysis revealed 22.5% Hb Malay, 64.6% Hb C and 4.5% Hb A2. Globin gene analyses demonstrated that she carried the betaC mutation (beta6: GAG-AAG) in trans to the betaMalay mutation (beta19: AAC-AGC). Hematologic data of the patient were compared to those of the compound heterozygote for Hb C and Hb E (alpha2beta(2)26Glu-Lys) found in 5 other unrelated Thai pregnant women and 11 pregnant women with Hb C heterozygote with or without co-inheritance of alpha-thalassemia who had much lower Hb C levels and the non-pregnant women with Hb C heterozygote and a compound Hb E/Hb Malay syndrome. Different genotype-phenotype correlations observed in these Thai patients with Hb C disorders are illustrated.

Adult↗
PubMed2005

Biochemical properties of beta-glucosidase in leukocytes from patients and obligated heterozygotes for Gaucher disease carriers.

BACKGROUND: Gaucher's disease (GD) is a disorder caused by the deficiency of lysosomal beta-glucosidase, an enzyme that participates in the degradation of glycosphingolipids. Deficiency of this enzyme results in the storage of glucocerebrosides in lysosomes of macrophage. No studies are available in the literature comparing biochemical and kinetic behavior of this enzyme in leukocytes and fibroblasts from normal individuals, obligate heterozygotes and patients with GD. METHODS: The behavior of beta-glu in terms of optimum pH, heat stability, Km and Vmax in leukocytes from patients with GD and obligated heterozygotes with different genotypes and normal individuals were characterized. RESULTS: Optimum pH was similar in all groups analyzed. In terms of Km and Vmax, several differences among heterozygotes and homozygotes groups and among these groups and normal enzyme were observed. Enzyme from all groups were inactivated when preincubated at 60 degrees C, but some enzymes were more stable than other. Results showed a different behavior of the enzyme in the 3 groups under analysis. Such behavior varied according to individual mutation. CONCLUSIONS: The catalytic gradient presented by beta-glu allowed the correlation of N370S mutation-which presented more stable biochemical properties-with the non-neurological clinical condition of the disease and the catalytically less stable mutation (D409H), with the neurological clinical condition of GD. This study contributes to a better understanding of the repercussion of the different mutations on the protein function, thus allowing to predict the severity of such complex metabolic disorder and to anticipate the most appropriate intervention for each case specifically.

Enzyme Stability↗
PubMed2004

Heterozygote AG variant of -596 A/G IL-6 gene polymorphism is a marker for cutaneous T-cell lymphoma (CTCL).

The aim of the study was to investigate possible associations of IL-6 gene polymorphisms (-596 A/G and -174 C/G) with cutaneous T-cell lymphoma (CTCL). In the case-control study, genotype distributions and allelic frequencies in two promoter IL-6 gene polymorphisms in the group of 63 Czech patients with CTCL were compared to those of 105 control non-CTCL subjects matched for age and sex. The IL-6 gene polymorphisms were determined by PCR with following restriction analysis. A significant difference of -596 A/G IL-6 genotype distribution was found between the CTCL patients and the controls (P = 0.002) with almost threefold odds ratio for the heterozygote (AG) genotype in CTCL patients (OR = 2.64, P = 0.002). No significant differences in genotype distribution and/or allelic frequency of functional -174 C/G IL-6 gene polymorphism were observed. The double heterozygote AGCG of both IL-6 promoter polymorphisms was associated with CTCL (OR = 2.24, 95% confidence interval 1.17-4.28, P = 0.01). Thus, the heterozygote variant of -596 A/G promoter IL-6 polymorphism could be considered as a genotype marker for CTCL.

Adult↗
PubMed2004

Primary fibroblasts from BRCA1 heterozygotes display an abnormal G1/S cell cycle checkpoint following UVA irradiation but show normal levels of micronuclei following oxidative stress or mitomycin C treatment.

PURPOSE: There is evidence to suggest that the breast cancer predisposing gene, BRCA1, is involved in cell cycle control and the response to damage but mouse brca1+/- heterozygotes have no distinctive phenotype. Here the response to the three forms of cellular stress was examined in primary human fibroblasts from individuals with a +/+ or +/- genotype for BRCA1. METHODS AND MATERIALS: Fibroblasts from individuals carrying mutations in the BRCA1 gene were compared with those from those wild-type for BRCA1 in their response to long wavelength uv (UVA), hydrogen peroxide, and mitomycin C (MMC). Cell cycle progression and micronucleus formation (MN) were used as end points. RESULTS: After UVA treatment there was no difference between +/- and +/+ cells in the initial fall in DNA synthetic activity (G(1) arrest) but the reentry into S-phase was restored at a faster rate in the BRCA1+/- cells after UVA exposure. Thus, for three normal (+/+) cell lines irradiated in monolayer, S-phase values averaged 15 +/- 3.7% 14 h post-UVA (1 x 10(5) J/m(2)), as compared with 35.7 +/- 1.9 (range) for two BRCA1(+/-) strains. Because a defective G(1)/S checkpoint in BRCA1 heterozygotes could lead to a greater proportion of S-phase cells with unrepaired DNA damage (strand breaks) and a resultant increase in chromosomal instability, the frequency of micronuclei induced by UVA was examined. Three normal (+/+) and three mutant (+/-) strains (two of which were used in the cell cycle experiments) produced mean micronuclei frequencies of 0.077 +/- 0.016 and 0.094 +/- 0.04/binucleate cell respectively (not statistically significant), 48 h after UVA exposure. No differences were found between BRCA1+/+ and +/- cells in MN formation after treatment with MMC or hydrogen peroxide. CONCLUSION: Our data suggest a defective G(1)/S checkpoint in cells from BRCA1 heterozygotes in response to UVA although this is not reflected in genomic instability as measured by micronuclei induction after oxidative stress or MMC treatment.

Alkylating Agents↗