In 1959, Down syndrome was shown to be associated with an extra chromosome in the G group1; Klinefelter syndrome was associated with an extra X chromosome2; and a case of double aneuploidy, a 48,XXY,G + male, was reported.3 In 1971, Erdtmann et al summarized 16 cases with this form of double aneuploidy.4 Two of the patients were adults, and these men had obvious phenotypic abnormalities. We report here results of endocrine, cytogenetic, and in vitro testicular steroidogenesis studies in a 19-year-old man with a 48,XXY,G + chromosome constitution, who lacked many of the classical features of Down or Klinefelter syndromes.
A white man aged 19 years 3 months was referred because of underdeveloped testes, incomplete sexual maturation, and obesity. He had the following history: The second of four children, he was born following an uncomplicated pregnancy and delivery. As he grew, obesity and a moderate degree