Neuroscience Institute

The eXtraordinarY Kids Clinic Research Program at Children’s Hospital Colorado

Contact Info

Can my child participate in a research study?
If you are interested in learning more about our current research studies and seeing if your child is eligible for a research project, please contact Susan Howell at 720-777-8361 or susan.howell@childrenscolorado.org.

X&Y Chromosome Variations Research
(720) 777-8361


Research in the eXtraordinarY Kids Clinic

Since 2007, our eXtraordinarY Kids Clinic team has been conducting clinical research in X&Y chromosome variations in order to learn more about how people with X&Y chromosome variations think, feel and solve problems. Our research studies span many areas, including learning, language, emotions and motor skills. Through research, we hope to better understand the strengths and weaknesses in these areas for individuals with X&Y chromosome variations, as well as how genes on the X&Y chromosomes may influence these different areas.  

Research goals

The three main goals of our research include:
  1. To study the development, learning, behaviors, emotions and motor skills in children and young adults with X&Y chromosome variations.
  2. To study different genetic factors of the X and Y chromosomes to determine if they are associated with the strengths and weaknesses in learning, behavior and motor skills and to develop new laboratory tests to identify X&Y chromosome variations.
  3. To study the physical appearance and other medical problems common in children and adults with different forms of X&Y chromosome variations.

Our current research also includes learning more about changes that occur with hormone replacement (testosterone) in a subgroup of adolescent or young adult males with an extra X chromosome (XXY, also known as Klinefelter Syndrome). We are looking at changes in learning, behavior, emotions and motor skills before and after testosterone therapy, and in comparison to males with an extra X chromosome who do not receive testosterone.

Our current research for sex chromosome variations

We are currently recruiting subjects for our clinical trial: “The Effects of Testosterone Therapy in Young Adolescents with Klinefelter Syndrome.”

This study investigates the effects of testosterone therapy on behavior, mood, problem solving, attention span and motor skills in adolescent males with Klinefelter syndrome in early puberty. During this period in early puberty, there is much variability in how and when doctors start testosterone therapy. This study will evaluate if there are benefits to starting testosterone therapy in early puberty.  

Participants with Klinefelter syndrome in early puberty (around ages 10 to 15) will be treated with either testosterone gel or a placebo (inactive) gel and followed for one year. Participants will be followed for changes in behavior, emotions, cognitive abilities, executive functioning, motor skills (strength, balance, coordination) and physical features (pubertal development, body habitus, gynecomastia).  

This study is conducted in Denver and includes 5 visits over 1 year. Study assessments include IQ and executive function assessment, motor skills assessment and behavioral questionnaires completed by the participant and caretakers. The testing is conducted in two sessions of approximately 3 ½ hours each over 1 to 2 days during select visits. Participants are provided with the study medication and gift cards as a token of appreciation. Travel to Denver, Colorado may be provided.

Assessments are completed as part of the research study, and a summary of research testing results will be provided. This study is funded by the National Institutes of Health (NIH).

Can my child participate in a research study?

If you are interested in learning more about our current research studies and seeing if your child is eligible for a research project, please contact Susan Howell at 720-777-8361 or susan.howell@childrenscolorado.org

Learn about symptoms, tests and treatments for X&Y chromosome variations.