Structural X-chromosome abnormality in a female with gonadal dysgenesis.

A patient with gonadal dysgenesis and 46 chromosomes is described. In the inactive X chromosome there seems to be a deletion of the short arms and an insertion of heterochromatin in the long arms. The most probable mechanism to explain this structurally abnormal X is a pericentric inversion, with breakage and union having occurred in the centromeric heterochromatin of the short arm and in band q23 of the long arm. An amplification of the centromeric heterochromatin left in the short arm is also supposed.