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The eXtroardinarY Babies Study: Natural History of Health and Neurodevelopment in Infants and Young Children With Sex Chromosome Trisomy

Who can join

6 Weeks – 13 Months · All sexes

Inclusion Criteria:

1. Prenatal diagnosis of sex chromosome aneuploidy (by cfDNA, chorionic villi sampling, and/or amniocentesis)
2. 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)
3. English or Spanish speaking
4. Age 6 weeks to 12 months 30 days on enrollment

Exclusion Criteria:

1. Previous diagnosis of a different genetic or metabolic disorder with neurodevelopmental or endocrine involvement
2. Prematurity less than 34 weeks gestational age
3. Complex congenital malformation not previously associated with sex chromosome aneuploidy
4. History of significant neonatal complications (ie intraventricular hemorrhage, meningitis, hypoxic-ischemic encephalopathy)
5. Known complex Central Nervous System (CNS) malformation identified by neuroimaging

About the study

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.

What is being tested

• Assessments of Development and Growth (other)

Sponsor: University of Colorado, Denver · Participants: 300 · Started: Sep 29, 2017

Contact the study team

• Nicole Tartaglia, MD, MS · Phone: (720) 777-8087
• Susan Howell, MS, CGC, MBA · Phone: 720-777-8361

Official record on ClinicalTrials.gov — NCT03396562

Locations in the U.S.

Conditions

• Learning Disabilities

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.