Anomalies of development in a girl with unusual sex chromosomal mosaicism.

Morphological abnormalities of the X chromosome are well documented and have been extensively reviewed and discussed by Ferguson-Smith (1965). They include isochromosome of the long arm, deletions of the long and short arms, ring chromosomes, and chromosomal fragments. Other types of abnormality are rare. Engel and Forbes (1965) described a chromatin negative girl (Patient No. 27) with a mosaicism of an XO line and an X large metacentric stem, which could have been an isochromosome. Mann, Valdmanis, Capps, and Puite (1965) described a girl with primary amenorrhoea who had an abnormality deduced to be due to a reciprocal translocation between an X and a B autosome, and Wie Lie, Coenegracht, and Stalder (1964) studied a mentally retarded girl with Turner's syndrome and a large metacentric chromosome replacing an X-6-12 chromosome in all cells. We here present a patient with some features of gonadal dysgenesis who was found to have mosaicism with an XO line and a 46 line, with a morphological abnormality, probably of an X chromosome. In addition, there were unusual radiological and electroencephalographic features.