A fertile man with tdic(Y;22): how a stable neo-X1X2Y sex-determining mechanism could evolve in man.

We describe a normal man with the karyotype: 45,X,dic(Y;22)(Ypter----Yq11.23::22p11.2----22qter+ ++). A brother and father of the propositus also had 45 chromosomes with the same dic(Y;22). Carriers of this chromosome are of normal phenotype, and the carrier of reproductive age had apparently normal fertility. A neo-X1X1X2X2/X1X2Y sex-determining mechanism can be considered to be operating in this family.