Henry Gershowitz

Specific Differences in the Inhibition Titers of the Anti‐H Lectins from Cytisus sessilifolius and Ulex europaeus*

Test of two commonly used anti‐H reagents (extracts from Cytisus sessilifolius and Ulex europaeus) demonstrated that group O secretors have the highest titer of H substance, with A2, A1, B, and AB followhing in that order. A comparison between the two extracts indicated that saliva belonging to persons of group A1 have about the same amount of both Hu and Hc (substances inhibiting the Ulex and Cytisus extracts respectively), A2 and O groups have a much higher titer of Hu substance than they do Hc, and B and AB groups demonstrate exactly the opposite qualities, with higher Hc than Hu titers. The most plausible explanation of the data seems to be that at least two different types of anti‐H specifities are involved (anti‐Hc and anti‐Hu); these extracts, then, differ not only quantitatively, but qualitatively as well.

Inheritance of quantitative expression of erythrocyte glucose-6-phosphate dehydrogenase activity in the Negro—a twin study

Studies have been conducted on eight sets of monozygous and nine sets of dizygous female Negro twins, both members of whom were heterozygous for G-6-PD deficiency. Twins were studied both by assay of erythrocytic G-6-PD activity and by the methemoglobin elution test (MET). The MET is a procedure which identifies histochemically cells with appreciable G-6-PD activity and permits accurate determination of the percentage of such cells in heterozygotes. Monozygous twins showed significantly less “within-pair” variation than dizygous twins with both the MET and G-6-PD assay.Concerning the significantly greater agreement in MET results in monozygous twins than dizygous twins, our present working hypothesis is that X-chromosomal inactivation in the Negro female is genetically controlled, rather than random. However, certain alternate hypotheses allowing for random X-inactivation have not been excluded; these include somatic cell selection after random X-inactivation, and cell exchange between identical twins in utero/it. Studies in nontwin related heterozygotes now underway should help differentiate among these various possibilities.In addition to the studies on 17 pairs of female twins heterozygous for G-6-PD deficiency, 26 pairs of nondeficient female Negro twins have been studied by G-6-PD assay. Within-pair variation in monozygous twins was significantly less than within-pair variation in dizygous twins in all cases. The genetic influences detected with the G-6-PD assay in the female twins could theoretically be due to nonrandom X-inactivation, to genetically determined quantitative differences in enzyme activity (e.g., isoalleles), or to both. By appropriate calculations, based on the MET results, we have factored out the effects of X-inactivation on overall enzyme activity in the heterozygous deficient twins. After removal of the effect of X-inactivation, monozygous twins heterozygous for enzyme deficiency continue to show significantly less within-pair variation than dizygous twins. This finding indicates significant genetic influences on quantitative G-6-PD activity other than X-inactivation and other than the deficiency allele. This conclusion has been strengthened by studies on male twins where X-inactivation is not present.

A pilot study of the use of placental cord blood samples in monitoring for mutational events

A pilot study exploring the examination of placental cord blood samples for mutant proteins with one-dimensional electrophoretic techniques is described. Although technical advances are such that the techniques employed in this study are now partially superceded, the practical problems encountered in this study would be typical of any monitoring program of this type. No mutations altering electrophoretic mobility among a battery of 51 different locus products were encountered in a total of 277,747 locus tests. When these data are combined with similar data from other studies, the mutation rate for electromorphs becomes 0.34 X 10(-5)/locus/generation.

Differences between families in the amount of salivary H substances

The saliva ABO inhibition titres of the members of twenty‐eight 0X0 and ten BxO mating types were determined. The results of the examinations suggest that: (1) A precursor ‘H’ substance is formed by all secretors which is converted into A, B, or AB depending on the individuals blood group. (2) the titres of the H substance secreted by members of the same sibship and of the same blood group are very uniform (high intra‐class correlation) indicating genetic control over the amount of the soluble ABO substances secreted. A genetic hypothesis was put forward to account for these findings.

The Evolutionary Relationships of Two Populations: A Study of the Guaymi and the Yanomama [and Comments and Reply]

A multidisciplinary study of the Guaymi of western Panama was undertaken to confirm or disprove their apparent similarity to the Yanomama of southern Venezuela and northern Brazil, inferred from allele frequencies for six polymorphic loci studied in the Guaymi by Matson and colleagues in 1965. Gene frequencies were estimated from the present sample of 484, which is more than twice as large as the previous sample and appears to be completely independent of the latter. The findings replicate the gene frequencies obtained earlier, within the terror of resampling after a decade. Leukocytes were typed for A and B locus specificities of the HLA system in 22 Guaymi. A specificity (HLA Bw15) absent from the Yanomama is present in high frequency in the Guaymi. Elsewhere we have reported that a polymorphism of serum albumin in the Yanomama is not present in the Guaymi but that the Guaymi possess polymorphisms of acid phosphatase and lactate dehydrogenase not present in the Yanomama. These findings make any close evolutionary relationship between the two tribes unlikely. Anthropometric data, though not extensive for other tribes, support the conclusion reached from gene frequencies. Of four tribes for which comparable measurements are available, three are more similar to the Guaymi than are the Yanomama, as judged by Mahalanobiss distance. Linguistic studies suggest that the Yanomama language (lexicon) has a larger fraction of cognates with Guaymi than does any other language compared here; however, two other languages in the series (Cashinahua and Shipibo) have higher cognate density with Yanomama than does Guaymi.

Further studies of Xh, a serum protein antigen in man.

Abstract. Xh has been identified as a serum protein antigen whose expression is both age and sex dependent, and is shown here to be identical with the antigen previously reported as Pa 1. On immunodiffusion, approximately 75% of randomly selected sera from females of all ages form a precipitin line with specific rabbit antiserum. Frequency of the antigen in females is correlated with age; 94% over 19 years of age are positive while only 55% under 19 are positive. Approximately 47% of male sera are positive; no significant changes in frequency associated with age of males were found. The mean level of the antigen in the sera of females over 19 years of age is approximately twice that in male sera. The heritability of Xh expression on the basis of a study of male twins was 0.66.

THE BLOOD GROUP POLYMORPHISMS: WHY ARE THEY THERE?*

Publisher Summary This chapter discusses the blood group polymorphisms and describes the ABO system. Formulation polymorphisms are of two chief types: (1) transitional and (2) balanced. In the case of the transitional polymorphism, a mutant gene replaces an established allele. Differences between the genotypes of a genetic system in viability and/or fertility of the order of 1 or 2% can, over a series of generations, be quite effective in stabilizing a polymorphism. The Rh system is the classic example of how blood group antibodies can act to effect selection. Selection is exercised when mother and child are of the proper Rh types, and the selective affect is greater when mother and child are of the proper ABO type.

Genetic Structure of the Garifuna Population in Belize

The Garifuna community is of particular interest to students of population genetics because it represents a group of people who have been relatively isolated, culturally and genetically, for the last 200 years. Their demographic and migratory patterns can be traced and a genetic profile constructed from exami¬nation of hemoglobins, red cell enzymes, and serum proteins.

Gm Allotypes in Mother-Father-Cord Trios

Abstract. When tested at a standard dilution (I:30), mother‐cord Gm phenotypes are identical. A more sensitive assay reveals that the fetus does possess paternal antigen, that is, does produce small amounts of autologous IgG. The paternal antigens, in both the mother and the cord plasma, appear in a mosaic, one that suggests the fetus has the ability to selectively transfer his own IgG subclasses to the mother.

Immunoglobulin (Gm and Km) allotypes in the Aymara of Chile and Bolivia

Immunoglobulin (Gm and Km) allotype and haplotype frequencies are presented for 1707 individuals from Northern Chile and Western Bolivia, subdividing them by ethnicity and altitude of residence. The haplotype distribution of Gm as well as Km loci in these populations suggest that in almost all of the ethnicity x altitude subdivisions of this population considerable admixture of Amerindian and Caucasian genes have occurred. The haplotype frequency heterogeneity and the analysis of departure from Hardy-Weinberg expectations demonstrate that while some local variation in haplotype frequencies at the Gm and Km loci exists in this region, there is no clear evidence suggesting that the pattern of variation is due to an adaptation to the hypoxia of altitude. We conclude that such differences in haplotype frequencies are probably due to random genetic drift and differential admixture of Amerindian and Caucasian genes that have occurred in the past.