Study of Psychological and Motor Effects of Testosterone in Adolescents With XXY/Klinefelter Syndrome (TestoXXY/KS)

• Change from baseline on the Delis-Kaplan Executive Function System [ Time Frame: Visit 1 (baseline) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  A collection of subtests from the Delis-Kaplan Executive Function System will be used to evaluate different domains of executive functions including planning, problem solving, fluency, inhibition, and working memory.
• Change from baseline on the Bruininks-Oseretsky Test of Motor Development - 2 [ Time Frame: Visit 1 (baseline) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  This test evaluates many aspects of motor functioning including fine and gross motor skills, visual motor integration, motor planning, and motor coordination
• Change from baseline on the Conners' Parent Rating Scales [ Time Frame: Visit 1 (baseline), Visit 4 (6 months) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  This questionnaire allows parents to rate many aspects of behavior including attention, hyperactivity, anxiety, social skills, and emotional lability.

• Change from baseline on the Vineland Adaptive Behavior Scales [ Time Frame: Visit 1 (baseline) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  The Vineland is an interview evaluating adaptive skills in the areas of communication, daily living skills, social skills, and motor skills.
• Change from baseline on the Wechsler Intelligence Scale for Children - Fourth Edition [ Time Frame: Visit 1 (baseline) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  This standardized assessment of cognitive functioning allows for evaluation of verbal and nonverbal cognitive skills, working memory, and processing speed.
• Change from baseline on the Comprehensive Test of Phonological Processing [ Time Frame: Visit 1 (baseline) and Visit 5 (1 year) ] [ Designated as safety issue: No ]
  This standardized test evaluates reading and language skills.

The purpose of this study is to determine if testosterone replacement therapy leads to changes in psychological factors and/or motor skills in adolescent males with 47,XXY (also called Klinefelter syndrome). This study will also evaluate whether certain genetic factors of the X chromosome affect the psychological or motor features of XXY/Klinefelter syndrome.

Klinefelter syndrome (47,XXY) is the most common chromosomal abnormality in humans and occurs in approximately 1 in 650 males. Testosterone deficiency develops during adolescence in the majority of individuals with XXY. However, there are no previous studies that evaluate the psychological and motor effects of testosterone replacement therapy in adolescents with XXY.

The study researchers are interested in learning if testosterone therapy initiated in early puberty in XXY (KS) will lead to improvements in psychological and/or motor skills. They are also interested in learning if genetic variations of the androgen receptor gene or the parent-of-origin of the extra X chromosome influence the response to testosterone therapy.

Specific psychological factors to be studied include verbal and nonverbal cognitive skills, attention, executive function (organization, problem-solving skills, inhibition), anxiety, language, self-esteem, and other behavioral factors. Motor skills to be studied include gross and fine motor skills, motor coordination, and motor planning.

Participants in the study will be randomized to one of two treatment groups, receiving either testosterone gel or placebo, for 12 months. 60% of the study group will receive testosterone, and 40% will receive placebo.

The research participants, parents/caregivers, and the members of the study team will be blinded to the treatment group, and will not know whether they are receiving testosterone gel or placebo treatments.

The supervising endocrinologist for the study will not be blinded and will know which patients are in the testosterone and placebo groups. This will allow him to monitor results to determine if participants in the placebo group may develop a significant need for testosterone therapy during the study period. If this occurs, the patient will be switched to the testosterone group and will continue to be monitored in the study.

All participants will be evaluated at the beginning of the study and at 1, 3, 6, and 12 months. Travel costs are included. Evaluations will include a combination of psychological and motor skills testing, questionnaires completed by the parent/caregiver and study participant, physical examinations, and blood draws for safety monitoring and genetic studies.

Participation in the trial will last one year and includes 5 clinic visits to the eXtraordinarY Kids Clinic at Children's Hospital Colorado in Denver.

• Klinefelter Syndrome
• XXY Syndrome

• Drug: Testosterone gel 1%
  Testosterone gel will be administered on a daily basis. The gel will be dispensed in a syringe, and the specific amount of gel to be applied each day will be determined by the study endocrinologist after reviewing labs.
• Drug: Placebo gel
  The placebo gel will be administered on a daily basis. The gel will be dispensed in a syringe, and the specific amount of gel to be applied each day will be determined by the study endocrinologist.

• Experimental: Testosterone gel
  Intervention: Drug: Testosterone gel 1%
• Placebo Comparator: Placebo gel
  Intervention: Drug: Placebo gel

Inclusion Criteria:

• Males with 47,XXY
• Participants must be in early puberty (Tanner stage II-III)
• Age 8 - 18 will be considered, but eligibility will be determined by review of laboratory results, bone age X-ray, and physical examination to determine stage of puberty
• All racial and ethnic groups

Exclusion Criteria:

• Other genetic variations of Klinefelter syndrome (48,XXXY, 48,XXYY, 49,XXXXY). The investigator has other studies for these groups and we encourage interested individuals with these disorders to contact us about other available studies.
• 47,XXY plus another genetic disorder
• Non-English speaking individuals (because the psychological tests are administered in English)
• Participants with a medical history of blood clotting problems, blindness, deafness, or cancer

• Colorado Clinical & Translational Sciences Institute
• Children's Hospital Colorado
• National Institute of Neurological Disorders and Stroke (NINDS)