James E. Bowman

Population Studies in Cameroon

: Examination of blood samples from 1,183 individuals from Cameroon indicates that sickle cell trait frequencies and G6PD deficiency frequencies were heterogeneous among villages as well as within geographic areas and ethnic groups. Mean parasite counts were significantly correlated with Hb AS frequencies for children 6 years of age and under, although no correlation was found for mean parasite counts and G6PD deficiency frequencies. The mean age of sickle cell trait individuals was found to be significantly greater than the mean age of Hb AA individuals. The mean age of G6PD-deficient males did not differ from the mean age of G6PD-normal males. Hb AA and Hb AS children did not differ significantly in mean positive parasite counts. Falciparum malaria appears to be a selective pressure keeping Hb S frequencies high; yet it may not be the major selective force maintaining the G6PD polymorphism.Examination of blood samples from 1,183 individuals from Cameroon indicates that sickle cell trait frequencies and G6PD deficiency frequencies were heterogeneous among villages as well as within geographic areas and ethnic groups. Mean parasite counts were significantly correlated with Hb AS frequencies for children 6 years of age and under, although no correlation was found for mean parasite counts and G6PD deficiency frequencies. The mean age of sickle cell trait individuals was found to be significantly greater than the mean age of Hb AA individuals. The mean age of G6PD-deficient males did not differ from the mean age of G6PD-normal males. Hb AA and Hb AS children did not differ significantly in mean positive parasite counts. Falciparum malaria appears to be a selective pressure keeping Hb S frequencies high; yet it may not be the major selective force maintaining the G6PD polymorphism.

The demonstration of asymmetric hemoglobin hybrids by polyacrylamide electrophoresis.

A simpler, more economical technique than previously reported, that of conventional polyacrylamide gel electrophoresis alone, is described for the detection of asymmetric hemoglobin hybrids of the forms alphaXalphaYbeta2 and alpha2betaXbetaY when bloods from individuals with alpha and beta chain variants were examined. The presence of alpha chain variant hybrids, never before reported, is further evidence that hybrid formation is a more widespread phenomenon than has previously been thought of. Hybrids were found in artificial mixtures of hemoglobins and more importantly, are also reported here for the first time in bloods of individuals heterozygous for hemoglobin variants. These hybrid tetramers were as stable as the parent hemoglobins when examined under anaerobic conditions. The involvement of HbF in the formation of hybrids of the type alpha2betagamma is reported, and an analysis of the possible role of these as well as alpha2betaAbetaS hybrids in the sickling process is presented.

Interaction of Sickle Cell Trait and Glucose-6-Phosphate Dehydrogenase Deficiency in Cameroon

The prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency and sickle cell trait was determined in 371 Cameroonian males and 668 male blood donors in Chicago. The number of males with both sickle cell trait and G6PD deficiency was significantly greater than expected (p less than 0.05) in Cameroon. The number of males with both sickle cell trait and G6PD deficiency in the Chicago population also exceeded the exptected number, although this was not statistically significant (p greater than 0.30). A young red cell population associated with the sickle cell gene leading to elevated G6PD levels in G6PD-deficient males suggests that sickle hemoglobin may exert a beneficial effect on G6PD deficiency, rather than the opposite, as had previously been proposed. These red cells may be better able to deal with oxidative stress, which can precipitate severe hemolytic disease in G6PD deficiency.

Minority Health Issues and Genetics

The Federal government has had many conferences on ethical guidelines involving minorities in research and in genetic testing. Examples of governmental violation of its own ethical precepts will be given with respect to invasion of privacy of employees, dissimulation about the role of abortion in genetic testing, and in sponsoring research abroad that would not be countenanced at home.

Theoretical evidence for an autosomal modifying gene pair in glucose‐6‐phosphate dehydrogenase‐deficient families

1 Various glucose‐6‐phosphate dehydrogenase‐deficient pedigrees from the literature violating classical patterns of sex‐linked inheritance are reviewed and discussed. 2 It is suggested that anomalous phenotypes observed in these families may be the result of epistatic reactions between the effects of abnormal sex‐linked genes or gene and an autosomal pair.

Genetic variation in Cameroon: thermostability variants of hemoglobin and of glucose-6-phosphate dehydrogenase.

The technique of heat denaturation was used in addition to electrophoresis for the detection of thermostability variants of hemoglobin and glucose-6-phosphate dehydrogenase in an attempt to measure the amount of genetic variability present in villages in the United Republic of Cameroon, Equatorial Africa. A minimum of three to a maximum of 13 thermostability variants were estimated for HbA and HbS, and a minimum of two to a maximum of ten thermostability variants were estimated for GdA, GdB, and GdA —. It is suggested that hemoglobin and glucose-6-phosphate dehydrogenase thermostability variants are genetically determined and that the sites of these variants are at the hemoglobin and glucose-6-phosphate dehydrogenase structural loci. The evidence for the existence of these hidden variants and their importance in the neutralist v. selectionist controversy are discussed.