The Detection of Klinefelter's Syndrome at Birth

A total of 2,176 newborn boy babies were screened for the prospect of having Klinefelter's syndrome by comparing phenotypic sex and nuclear sex. A discrepancy between the phenotypic sex and the nuclear sex, suggestive of the presence of the aneuploid karyotype as sociated with Klinefelter's syndrome, was found in seven babies, and confirmed by chromosome analysis. Despite the essentially normal physical examination typically reported at birth in babies with Klinefelter's syndrome, phenotypic hints of the presence of the disease in the form of undescended or unusually hard or soft testes were noted in three of the seven infants. Genetic counseling of both the families and the pediatri cians was only moderately well received, because of the seeming normality of the babies. Pediatri cians should be aware that Klinefelter's syndrome can be recognized at birth, and that genetic counseling and long-term follow up are advisable.