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C Y Valenzuela

Publications and source records attributed to C Y Valenzuela.

At least 55 records · Page 3Linked to original sources
PubMed1985

Selective interactions among Rh, ABO, and sex ratio of newborns.

The hypothesis that the Rh and ABO blood systems behave like the HLA system in relation to mother-conception tolerance-rejection mechanisms was tested in 25,501 mother-infant pairs. According to this hypothesis, heterozygotes carrying a paternal gene that is not present in their mothers should be better tolerated than homozygotes. Significantly more BO infants born to AO mothers. AO infants born to BO mothers, Rh(+) heterozygotes born to Rh(-) mothers, and less significantly AO infants born to OO mothers confirm the hypothesis. Fewer homozygotes occurred in Rh(-) infants born to Rh(+) mothers and in O infants born to non-O mothers. Deviations from the Hardy-Weinberg equilibrium found in the ABO system were modified by the Rh and sex of the infant. These data strongly support the hypothesis that at least two feto-maternal systems influence the destiny of pregnancies: the classical known incompatibility system which operates late in pregnancy and a new one which is based on the induction of maternal tolerance early in pregnancy: maternal tolerance seems to be better elicited by heterozygous eggs or embryos carrying a gene not present in the mother. The data also support the hypothesis that the sex ratio is influenced by feto-maternal tolerance-rejection mechanisms associated with the ABO and Rh systems.

ABO Blood-Group System↗
PubMed1983

Pubertal origin of the larger sex dimorphism for adult stature of a Chilean population.

Students aged 6 to 20 years attending the public schools in the Northern Area of Santiago, Chile, were examined to search for the developmental origin of the large sex dimorphism in adult stature found in this population. Stature, biacromial diameter, and signs of sexual maturation were studied and comparisons were made with European samples. All of the variables showed that Chilean females reach puberty earlier than, and cease growth before Europeans, while males mature at the same pace as Europeans. It is concluded that the large sex dimorphism in adult stature found in this sample is mainly due to this earlier cessation of growth in Chilean females.

Adolescent↗
PubMed1982

A mother-child segregation distortion for the Rh system. New evidence for another compatibility system associated with Rh.

In the maternity service of a private hospital in Santiago, Chile, 6,974 mother-infant pairs typed for the D-d alleles of the Rh system were collected. In our analysis, all the paris attended from October 1974 to December 1975 and from January 1977 to September 1979 were used. The segregation analysis, made by means of the T mother-child matrix, assuming Hardy-Weinberg equilibrium, reveals that: Rh(-) mothers have a higher rate of admission than do Rh(+) mothers; Rh(+) mothers produce fewer Rh(-) infants than expected; and, with less significance, Rh(-) mothers produce more Rh(+) infants than expected. This leads to a reduction in the proportion of dd individuals from mothers to their children. Ethnic subdivisions of the sample, the period considered, and the extension of the antiisoimmunization therapy do not seem to affect the general pattern of the distortion. The only plausible hypothesis to explain this finding is that selection is not related to the known Rh antigenic specificities. The reduction of the proportion of dd individuals in 1 generation leads us to review models on Rh polymorphism. It seems clear that no classical compensation is possible and d must disappear unless another mechanism maintains it in populations.

Blood Group Incompatibility↗
PubMed1982

A large phenotypic sib-sib discordance for the Rh blood system. A possible new feto-maternal compatibility system.

A large sib-sib phenotypic discordance for the Rh system has been found in a longitudinal follow-up study on growth and development. Sibs born no more than 3 years later than their respective indexes show a significant tendency to have a different phenotype from that of their indexes. The hypothesis that distortion is due to eggs or fetal loss finds support in the existence of increased time intervals between indexes' and sibs' births in those cases in which the losses were suspected. Two groups of index families made according to the presence or absence of the cde haplotype in their genotype show important differences in segregation and reproductive patterns. The observed distortions cannot be explained by the differences in known antigenic Rh specificities. The existence of a new feto-maternal compatibility system would better fit these facts and would also allow the reinterpretation of several distortions associated with Rh described in the literature that have never been satisfactorily explained.

Birth Intervals↗
PubMed1979

[A model for determination of the expected numbers of chromosome alterations and break points].

The assumption that the expected number of chromosome break points is simple and directly proportional to the length of chromosomes is criticized. Translocations and inversions imply two dependent break points in relation to their distribution on the whole karyotype, that is why, this assumption should be modified. A model is presented which takes the dependence into account and which provides the formulas for the calculations of probabilities of binary rearrangements and of their respectives break points. We apply the model to the human karyotype.

Chromosome Aberrations↗