Cerebral germ cell tumor and XXY karyotype.

Metaphases from a cultured cerebral germ cell tumor (CGCT) in a boy with a 46,XY constitutional karyotype had 47 chromosomes with an additional X chromosome and a translocation (1;21)(q11;p11). CGCT appear to be nonrandomly associated with Klinefelter syndrome, and a supernumerary X chromosome and trisomy of the 1q21-->1qter region may be clonal abnormalities in these tumors. The predisposition of Klinefelter patients to develop CGCT may be due to the pathogenetic relevance of the extra X chromosome both as an acquired and a constitutional abnormality.