HLA-DQa allelic frequencies detected with PCR in a variety of human populations.

Polymerase chain reaction (PCR) amplification and oligonucleotide probe hybridization may be used to detect DNA polymorphisms rapidly in large samples. In this study, 475 individuals from thirteen human populations were allelotyped at the human leukocyte antigen (HLA) DQa (DQA1) locus. A 242 or 239 bp fragment was amplified from each individual's DNA. Each of six alleles was detected by hybridization to allele specific oligonucleotide probes (ASOs). Allelic frequencies varied between populations, but the measure of gene frequency variation among populations, the FST value, was relatively low. Most populations had genotypic frequencies in agreement with Hardy-Weinberg equilibrium expectations. Principal component analysis was performed on the populations, and results are presented in graphic form. The heterozygosity at this locus is high in all populations; the average (74%) is close to the theoretical maximum (83%) for a 6 allele system. It is likely that this system is affected by stabilizing selection, which makes it less than optimal for the study of random evolutionary divergence between populations.

Education and birth control.

PIP: Focus is on the demographic transition in Italy in relation to education. An analysis of the data of the Italian 1961 census in 3 provinces reveals a strong stratification of the transition to lower birthrates according to degree of education. A 50-year lag exists in the transition in the highest and lowest educational classes. Adjustment to a lower number of children occurred, on average, by a decrease in the age at last childbirth. However, the more literate classes begin reproduction at a later age. Educational differences explain only about 1/2, approximately, of the rural-urban difference in birthrates; different geographical areas show additional, independent retarding factors. The relationship of mean to variance of number of children ever had in postreproductive women, evaluated on relatively homogenous strata (by cohort and educational class), is practically linear (or at most, with a slight concavity downward) with a negative intercept. The relationship during reproductive age is instead concave upward. The observed mean-variance relationship in postreprductive women is in agreement with the hypothesis of the diffusion of the Malthusian ideal through the population, if the decision in favor of a Malthusian behavior in reproduction is not limited to reproductive age, but can occur at any age. Naturally, the conversion to a Malthusian ideal in a family after some children are already born would cause only a small reduction in the fertility of that family, thus introducing an element of gradualness in the change from the "natural" fertility behavior to the Malthusian one. The beginning of the transition is different in different educational strata for a variety of reasons.^ieng