Study of human Y chromosome polymorphism in Taiwan.

The Y chromosome is one of the human chromosomes carrying significant amount of constitutive heterochromatin. To investigate the prevalence of Y chromosome polymorphism and its clinical significance in Taiwan, we analyzed the Y chromosome among 6,286 unrelated males by G-banding and, if necessary, fluorescence in situ hybridization studies. The prevalence of the Y chromosome variants were: large Y (Yq+) 3.6%, pericentric inverted Y [inv(Y)] 0.27%, and small Y (Yq-) 0.59%, respectively. More than 99% of those variants were from their biological fathers. The incidence of the Y polymorphisms was similar in three groups: children with mental retardation, other chromosomal aberrations or multiple congenital anomalies, and normal controls. The Yq12 heterochromatin region may contribute to the variation in Y chromosome length. The prevalence of inv(Y) and Yq+ was higher than those in the white population. Our results conclude that there are no indications that Yq+, inv(Y) and Yq- are connected with any deviations in intelligence or with an increased risk of physical malformations or other chromosomal disorders, which is of great help for genetic counseling.