Clinical and hormonal status of infants with nonmosaic XXY karyotype

To compare our recent findings in a cohort of 77 nonmosaic XXY infants <2 years of age with clinical and biological features already reported.

The majority of reported XXY neonates had normal external genitalia. Only undescended testes and/or micropenis were identified reasons for referral. Delayed ambulation and speech skills were also indications for postnatally karyotyping. All subjects from our cohort (73 prenatally detected subjects, five postnatal diagnoses) had height and weight within the normal range, and were not dysmorphic. Insulin-like-peptide-3 and testosterone secretion by Leydig cells appeared normally sensitive to luteinizing hormone. In reported studies, inhibin B levels were within normal range, anti-Mullerian hormone levels were normal or high and follicle-stimulating hormone (FSH) levels were significantly higher than control values, data consistent with a relative resistance to FSH.

Early detection of Klinefelter syndrome is desirable for prospectively monitoring the apparition of developmental problems and the progressive decline in the tubular function of the testis, with the hope of designing future conservative interventions before germ cell degeneration is completed.