Centromere inactivation in a case of Turner variant with two dicentric iso-long arm Y chromosomes.

A 6-year-old girl of small stature and with some features of Turner's syndrome was found to have a karyotype with two-thirds of the cells possessing one, and one-third with two dicentric iso-long arm Y chromosomes. In metaphases with 46 chromosomes the majority of the abnormal Ys exhibited two primary constrictions. In cells with 47 chromosomes both isochromosomes prevalently had only one active centromere.