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Population and familial studies on the variability of the heterochromatic and euchromatic segments of the human Y chromosome

Jeanete M.S. Agostini^{I, II}; I.J. Cavalli^II; B. Erdtmann^III; Margarete S. Mattevi^III

^IDepartamento de Biologia, Universidade Federal de Santa Catarina, 88041 Florianópolis, SC, Brasil. send correspondence to J.M.S.A.
^IIDepartamento de Genética, Universidade Federal do Paraná, 81504 Curitiba, PR, Brasil
^IIIDepartamento de Genética, Universidade Federal do Rio Grande do Sul, 90001 Porto Alegre, RS, Brasil

ABSTRACT

The variability of the heterochromatic and euchromatic segments of the human Y chromosome was studied by a quantitative method of densitometric measurements in 60 normal and unrelated subjects (30 Caucasians and 30 Japanese) living in Brazil. The length of the Y chromosome depends on the heterochromatic as well as the euchromatic segment. In both comparisons the regression coefficient values were positive and statistically significant. The larger size of the Y chromosome in Japanese than in Caucasian individuals was due only to the heterochromatic segment. Heritability of the length of heterochromatic and euchromatic segments and of the total length of the Y chromosome was studied in 30 father-son pairs (15 Caucasians and 15 Japanese). Although all the father-son comparisons were statistically significant, the points related to the euchromatic segments of father-son regression showed central dispersion, with only a few outlying data, whereas the data for the heterochromatic segments of chromosome Y presented the expected distribution along the regression line.

Keywords: population; familial; variability; heterochromatic; euchromatic; segments; chromosome.

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