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ABO segregation analysis of sib-pairs in two brazilian samples^*

P.H. Cabello; M.F. Feitosa; H. Krieger

Departamento de Genética, Instituto Oswaldo Cruz, Av. Brasil, 4365, 21040 Rio de Janeiro, RJ, Brasil. Send correspondence to H.K.

ABSTRACT

Two Brazilian samples of more than 1000 sib-pairs each were analyzed for ABO segregation to test discrepancies of the equilibrium proportions reported by Cifuentes and Valenzuela (Rev. Brasil. Genet. IX: 727-734, 1986) for a Chilean sample. In contrast to the Chilean findings, no significant differences were detected either in the entire sample or when the sample was divided according to the mother's phenotype.
The pooled observations made on the present Brazilian samples and on the Chilean sample do not support the existence of a mechanism of "tolerance" as postulated by Cifuentes and Valenzuela (op. cit.).
The need for complete information about nuclear families is stressed in order to avoid inconsistent or spurious results.

Keywords: ABO; segregation; sib-pairs.

REFERENCES

Cabello, P.H. (1972). Freqüências gênicas e coeficiente de endocruzamento em uma população rural brasileira. Masters Thesis. Instituto de Biociências, Universidade de São Paulo.

Cifuentes, L. and Valenzuela, C.Y. (1986). Sib-sib segregation distortion for the ABO system. The influence of maternal phenotype. Rev. Brasil. Genet. IX: 727-734.

Krieger, H., Morton, N.E., Mi, M.P., Azevedo, E., Freire-Maia, A. and Yasuda, N. (1965). Racial admixture in Northeastern Brazil. Ann. Hum. Genet. 7: 308-316.

Li, C.C. and Sacks, L. (1954). The derivation of joint distribution and correlation between relatives by the use of stochastic matrices. Biometrics 10: 347-360.

Morton, N.E. (1964). Genetic studies of Northeastern Brazil. Cold Spring Harbor Symp. Quant. Biol. 29:69-79.

Morton, N.E., Krieger, H. and Mi,M.P. (1966). Natural selection on polymorphisms in Northeastern Brazil. Am. J. Hum. Genet. 18: 153-171.

Penalva da Silva, F. (1975). Incompatibilidade ABO no Nordeste Brasileiro. Aspectos formais e populacionais. Doctoral Thesis, Instituto de Biociências, Universidade de São Paulo.

Penalva da Silva, F. and Krieger, H. (1981). The maintenance of ABO polymorphism. Rev. Brasil.Genet. IV: 705-712.

* This paper is dedicated to Prof. Newton-Freire-Maia, Brazilian pioneer in human genetic research, in celebration of his 70th birthday