[The human genome--chromosome Y].

The Y chromosome, the only chromosome present only in the male karyotype, is one of the smallest human chromosomes. Its content of protein-forming genes is, as compared with other chromosomes, greatly reduced and if we omit the part homologous with the X chromosome it is really minimal. For normal development the area occupied by locus TDF or SRY can be considered essential. The antigenic locus HY is also associated with male sex. Well known are also the amelogenin locus which is in the pseudoautosomal area, the locus conditioning Kallmann's syndrome and locus ASMTY for hydroxyindole-O-methyltransferase--the last enzyme of the metabolic route to the pineal hormone melatonin. With regard to the presence of many highly polymorphous areas the Y chromosome is predestined for population studies where it supplements aptly investigations of the mitochondrial genome, and for investigations of cellular chimerism after allogeneic transplantations.