Major karyotypic abnormality in a child born to a woman with untreated malignant melanoma.

The karyotype of a 7-month-old child had 46 chromosomes, including five abnormal chromosomes in cultured lymphocytes. G-banding indicated the presence of reciprocal translocation products between chromosomes 1 and 7 and between chromosomes 4 and 15. A probable third translocation involved the same chromosome 4p arm and 12q. All metaphases showed these changes. C-band markers and the presence of reciprocal exchange products indicated that the chromosome changes occurred in the zygote or a post-zygotic cell of the child. The mother developed malignant melanoma while carrying the child but did not receive therapy before its birth. The suggestion is made that an undetected common agent was involved in the aetiology of the mother's tumour and the clastogenic change to the child's chromosomes.