Five hundred and ten students of the Universidad Nacional Autónoma de México were tested to determine the distribution of ABO, MN, Rr-Hr blood groups, and serum haptoglobin, albumin, and Factor Bf types. Based on the results we found that the proportion of Indian and White genes are of 56.16 and 43.84%, respectively in the dihybrid model and 2.93, 56.22, and 40.85% for Blacks, Indians, and Whites in the trihybrid one. The present study reveals a higher proportion of Indian genes in the Mexico City population than estimated in previous publications. Reasons why the present results apply to a much larger group of Mexico City mestizos than the previous ones are given.

Three hundred ninety-three individuals from the Universidad Autónoma de Puebla and its University Hospital were studied to determine the distribution of ABO, MN, Rh-Hr, Duffy, and Diego blood groups; red cell hemoglobin and glucose-6-phosphate dehydrogenase variants; and serum haptoglobins, albumins, and factor Bf types. With the results we estimated that the proportions of black, indian, and white genes are 10.7%, 56.3%, and 33.0%, respectively, in a trihybrid model. Reasons are given as to why the black ancestry may be artifically high, and it is pointed out that independent confirmation with other markers is needed before the figure can be accepted as a true value.

A 16-year-old Mexican male of Japanese ancestry was found to have a new glucose-6-phosphate dehydrogenase (G-6-PD) deficient variant, named Gd(-) Tepic after the birthplace of the maternal grandmother. A younger brother was also affected and the two sisters were heterozygous. The mother, an obligatory heterozygote, did not show the abnormal variant and the possible explanation of this phenomenon is discussed. From the clinical standpoint, the propositus has had three mild hemolytic episodes while his siblings are so far asymptomatic.

The distribution of ABO and Rh (antigen D) blood groups and of serum albumin, haptoglobin and transferrin variants, in a group of mothers of malformed newborns was investigated. In the first phase of the study, the results showed borderline statistical differences in the distribution of the transferrin types between the study group and a suitable control population. The second phase of the research, where only transferrin phenotypes were studied, showed the same trend as in the first one, but the results were not statistically significant. We conclude that probably there are no true distribution differences, but that it would be desirable to study this problem in a different ethnic group.

The frequency of the serum atypical pseudochloinesterase variant was significantly higher (p less than 0.005) in a group of 115 lepromatous leprosy patients than in a comparison group of 133 healthy individuals. This finding corroborates the results obtained in the group of patients from India, and supports the contention that the serum atypical pseudocholinesterase is one of the possible genetic factors involved in susceptibility to leprosy.