Prevalence and molecular heterogeneity of alfa+ thalassemia in two tribal populations from Andhra Pradesh, India

We describe here the screening of a small group of apparently healthy individuals belonging to the tribal communities of Koya Dora and Konda Reddi. A remarkably high incidence of deletion and nondeletion alpha + thalassemia mutants has been found with allele frequencies and distributions characteristic to each tribe. We have confirmed the strict relationship between Hb S levels and the number of alpha globin genes in double heterozygotes for the S gene and alpha thalassemia. In this population sample we did not find either heterozygous carriers of alpha 0 thalassemia (deletion of both alpha genes in "cis") or individuals showing hemolytic anemia due to inactivation of three alpha-globin genes (Hb H disease). Selection by malaria is most probably responsible for the prevalence of the various alpha + thalassemia haplotypes among the two tribal populations of Andhra Pradesh.

Close linkage of a highly polymorphic marker (D5S37) to familial adenomatous polyposis (FAP) and confirmation of FAP localization on chromosome 5q21-q22

Fifteen apparently unrelated Dutch families with familial adenomatous polyposis (FAP) also known as familial polyposis coli (FPC; McKusick No. 17510) were screened for linkage with the DNA probe C11p11 localized on chromosome 5q21-22 and previously reported to be closely linked to FAP (Bodmer et al. 1987; Leppert et al. 1987). In our study C11p11 was minimally informative, which is ascribable to its low heterozygosity in the North European populations. Of the above families, 12 were investigated also for linkage with D5S37 (DNA probe Pi227). Data from 11 of them were found to be informative and showed that FAP is closely linked to D5S37 previously localized on chromosome 5q21 (peak lod score 7.85 at a recombination fraction of 0.048 with 95% probability limits 0.005-0.145). Results discussed below indicate for the first time that the most likely location of the FAP gene is in the band 5q22 very close to 5q21, if not in the transitional zone between these two bands. The probe Pi227 recognizes 4 restriction fragment length polymorphism (RFLP) sites, exhibiting a total of 9 alleles with 24 theoretically possible haplotypes in the Dutch population. Therefore, this probe appears to have potential as a generally useful predictive marker for FAP until much closer and similarly useful markers become available.

Severe combined immune deficiency due to a homozygous 3.2-kb deletion spanning the promoter and first exon of the adenosine deaminase gene

We have investigated the structural gene for adenosine deaminase (ADA) in a female infant with ADA deficiency associated severe combined immune deficiency (ADA-SCID) disease and her family by DNA restriction-fragment-length analysis. In this family a new ADA-specific restriction-fragment-length variant was detected, which involves a 3.2-kb deletion spanning the ADA promoter as well as the first exon. It was found that the patient, who was born to a consanguineous couple, was homozygous and both her parents and her brother were heterozygous for the deletion. No ADA-specific mRNA could be detected by hybridization in fibroblasts derived from this patient. Thus the patient was established to be homozygous for a true null ADA allele. In the light of the apparently normal development of most tissues except the lymphoid tissue the above finding directly questions the classification of ADA as a 'housekeeping' enzyme.

Human alpha-globin maps to pter-p13.3 in chromosome 16 distal to PGP

Fibroblasts from a fetus with an unbalanced karyotype 46(XY), -16,+(16qter-16p13.3::4q31.1-4qter) were found to possess only one allele at the 3' hypervariable region (3'HVR) close to the alpha-globin locus and two alleles at the PGP locus. This places the alpha-globin locus at the very tip of 16p, distal to PGP.

Electrotypes and formal genetics of red cell glutathione peroxidase (GPX1) in the Djuka of Surinam

Samples of venous blood from 239 male and 476 female adults including 41 pairs of parents and 123 of their children belonging to a Surinam population called the Djuka or Bush Negroes of West African origin were screened for electrophoretic variants of red cell glutathione peroxidase (GPX1) in Cellogel. The results confirmed an earlier hypothesis that at least a part of the GPX1 variation mainly, if not exclusively, observed in the Africans and people of African origin living elsewhere, is determined by two codominant alleles (called GPX1*1 and GPX1*2), at an autosomal locus. The frequency of GPX1*2 allele in the Djuka was estimated to be .054. A rare variant provisionally designed as GPX1 Djuka (thought to be a heterozygote due to a third allele called GPX1*3 and the GPX1*1) was found in two apparently unrelated individuals. Catalytically, the product of GPX1*2 appears to be about twice more active than that of GPX1*1. For heuristic purposes, it was proposed and discussed that GPX1*2 is a South-Saharan African allele and is amenable for natural selection.

Assignment of the human tissue-type plasminogen activator gene (PLAT) to chromosome 8

Using 1.2kb 3'-terminal Pst-I fragment of a full length tissue-type plasminogen activator (t-PA) cDNA clone (ptPA-8FL) and a set of rodent human somatic cell hybrids, the corresponding human gene PLAT was localized on chromosome 8.

Immunohistochemical localization of adenosine deaminase complexing protein in intestinal mucosa and in colorectal adenocarcinoma as a marker for tumour cell heterogeneity

Adenosine deaminase complexing protein (ADCP), a dimeric glycoprotein, has been reported to be decreased or deficient in transformed or cancer-derived cell lines, indicating its potential significance as an indicator of malignant transformation. A similar deficiency was reported in total homogenates of tumours of colon, kidney, lung and liver. In previous biochemical studies we failed to confirm the consistent reduction in ADCP concentration in cancer tissues. A possible explanation for our findings was thought to be intercellular heterogeneity in ADCP expression in individual tumour cells. To study ADCP expression in individual cells, we developed an immunohistochemical method which was applied to tissue sections. Paraformaldehyde--lysine--periodate (PLP) solution was found to be a suitable fixative. Fixed tissue samples were paraffin-embedded, sectioned and stained for ADCP, using an indirect peroxidase-labelled antibody procedure. The protein was localized in normal colonic mucosa, mainly in the brush border region of the luminal epithelium and in cytoplasmic granules. Intense ADCP immunoreactivity was found also in the basal part of some cells. In cancer cells, three staining patterns were observed: membranous, diffuse cytoplasmic and granular cytoplasmic. The adenocarcinomas exhibited significant intratumour and intertumour heterogeneity in their staining types. Further studies on ADCP expression in colorectal cancer in relation to clinical and histopathological characteristics are warranted in order to fully evaluate the potential significance of ADCP as a cancer associated antigen.

Quantitative changes in adenosine deaminase isoenzymes in human colorectal adenocarcinomas

Several reports have suggested that a decrease or absence of adenosine deaminase complexing protein (ADCP) is consistently associated with cancer. However, in other studies, decreased as well as increased ADCP levels were found. In the present study, we investigated ADCP levels in 37 colorectal adenocarcinomas and correlated the results with clinicopathological characteristics in individual carcinomas. The levels of adenosine deaminase (EC 3.5.4.4) and soluble ADCP were determined in tissue samples by, respectively, a spectrophotometric assay and an ADCP specific radioimmunoassay. The values in the individual tumors were compared with their histological characteristics, such as degree of differentiation, nuclear grading, and the preoperative plasma carcinoembryonic antigen levels in the patients. It was found that ADCP was decreased in about a third of the tumors but unaltered or even increased in others. However, there was an overall 40% increase of the adenosine deaminase activity in the tumors compared to normal tissue. There seems to be no simple correlation between any of the clinicopathological parameters and the ADCP or adenosine deaminase levels. Methods detecting ADCP at single cell level might be helpful in exploring its potential use as a cancer-associated marker.

Electrophoretic characterization and genetics of human biliverdin reductase (BLVR; EC 1.3.1.24); assignment of BLVR to the p14 leads to cen region of human chromosome 7 in mouse-human somatic cell hybrids

A simple chromogenic staining procedure is described for the specific identification of biliverdin reductase (BLVR) after gel electrophoresis. Using this procedure a gene for BLVR was assigned to the p14 leads to cen region of human chromosome 7 in human-mouse somatic cell hybrids. Incidentally, the study indicated that the NADH-as well as the NADPH-dependent BLVR activities are due to one and the same enzyme and that, most probably, only one gene in the human genome codes for BLVR and the BLVR is a monomer in its functional configuration.

Glutathione S-transferase activity in human fetal and adult tissues

Quantitative estimations of glutathione S-transferase activities with 1-chloro-2,4-dinitrobenzene as the electrophilic second substrate, in 142 postmortem human tissue specimens derived from 34 different organs of one or more of 13 individuals belonging to various age groups, are presented. Collectively the data indicate: (1) all tissues examined have appreciable levels of enzyme activity; (2) liver, kidney, lung, muscle, heart, adrenal glands, pancreas, and stomach of fetal origin possess higher enzyme activities than those of the adults, and (3) there are wide interindividual variations in the tissue enzyme activities.