This study is designed to research the natural history of neurodevelopment, health and early hormonal function in infants with XXY/Klinefelter syndrome, XYY, XXX and other sex chromosome variations in an effort to identify early predictors of developmental and health outcomes. The Investigators will also evaluate different developmental screening tools in infants with sex chromosome variations so the investigators can develop recommendations for pediatrician caring for infants and young children with XXY/Klinefelter syndrome, XYY, XXX, and other sex chromosome variations.
Prenatal diagnosis of sex chromosome aneuploidy (by cfDNA, chorionic villi sampling, and/or amniocentesis)
Postnatal confirmatory karyotype of XXY, XYY, XXX, XXYY, XYYY, XXXY, XXXX, XXXXX, XXXXY, XXXYY, XXYYY, XYYYY (including any mosaicism with <80% 46,XX or 46,XY cell line)
English or Spanish speaking
Age 6 weeks to 12 months 30 days on enrollment
Previous diagnosis of a different genetic or metabolic disorder with neurodevelopmental or endocrine involvement
Prematurity less than 34 weeks gestational age
Complex congenital malformation not previously associated with sex chromosome aneuploidy
History of significant neonatal complications (ie intraventricular hemorrhage, meningitis, hypoxic-ischemic encephalopathy)