Children's Hospital Colorado

The eXtraordinarY Babies Study

November 01, 2018
XXY/Klinefelter syndrome, XYY, XXX and other sex chromosome variations
6 weeks to 12 months old
COMIRB number

Purpose of the study

The eXtraordinarY Babies Study is designed to research the natural history of neurodevelopment, health and early hormonal function in infants with XYY, XXX and others in an effort to identify early predictors of developmental and health outcomes. We will also evaluate different developmental screening tools in infants with sex chromosome variations so we can develop recommendations for pediatrician caring for infants and young children with XXY/Klinefelter syndrome, XYY, XXX and other sex chromosome variations.

Research details

Children age 6 weeks to 12 months old, who have a prenatal diagnosis of XXY, XYY, XXX, XXYY and other sex chromosome variations are eligible. There will be four to eight study visits over a period of two to four years, depending on age and timing of enrollment.

Assessments will include:

  • Measures of skills in different areas of development including problem solving, language, social, motor and life skills
  • Physical exam
  • Blood, urine and stool testing for hormone levels, metabolic functioning and DNA banking
  • Scans for body composition (muscle and fat mass, bone density)
  • Quality of life outcomes
  • Questionnaires and surveys to be completed by parents or caregivers

You will be paid for each visit in this study, dependent upon how many visits are completed. You will help us gain valuable information about sex chromosome variations. The results of this study will help plan for future studies in sex chromosome aneuploidies.


To learn more about this study, email us at