CEREBRAL GERM-CELL TUMOR AND XXY KARYOTYPE

Metaphases from a cultured cerebral germ cell tumor (CGCT) in a boy wi th a 46,XY constitutional karyotype had 47 chromosomes with an additio nal X chromosome and a translocation (1;21)(q11;p11). CGCT appear to b e nonrandomly associated with Klinefelter syndrome, and a supernumerar y X chromosome and trisomy of the 1q21-->1qter region may be clonal ab normalities in these tumors. The predisposition of Klinefelter patient s to develop CGCT may be due to the pathogenetic relevance of the extr a X chromosome both as an acquired and a constitutional abnormality.