Impact of Early Hormonal Therapy (EHT) on the Neurobehavioral Profile of Boys with 47, XXY (Klinefelter Syndrome) at 9 Years of Age. C. Samango-Sprouse1,2,3,4, D. C. Gibbs3, E. Stapelton3, T. Sadeghin1, A. L. Gropman2,4 1) Neurodevelopmental Diagnostic Center for Young Children, Davidsonville, MD; 2) George Washington University School of Medicine, Washington, DC; 3) The Focus Foundation, Davidsonville, MD; 4) Children's National Medical Center, Washington, DC.

   47, XXY is associated with frontal lobe dysfunction and language-based learning difficulties contributing to a complex behavioral phenotype that may include ADHD and atypical social skills. Recent studies have shown the positive effects of early hormonal treatment (EHT) on the neurodevelopmental outcome of boys with 47, XXY in early childhood, but the effects of EHT on behavioral and social development have not been explored at later ages. 59 prenatally diagnosed 47, XXY boys [22 who received EHT (3 injections of 25 mg testosterone enanthate) and 37 who received no treatment] were evaluated at 9 years of age using the Behavior Rating Inventory of Executive Function (BRIEF), Social Responsiveness Scale (SRS-2) and Child Behavior Checklist (CBCL). Significant differences between group scores were tested using appropriate biostatistics. The EHT treatment group had significantly improved Global Executive Functioning (p=0.038), Monitoring (p=0.027) and Initiation (p=0.0023) on the BRIEF, significantly fewer Aggressive Behaviors (p=0.039) Affective Problems (p=0.002) and Total Problems (p=0.006) on the CBCL and improved social cognition (p=0.0045), social communication (p=0.0175) and fewer autistic features (p=0.0005) on the SRS-2. These results provide further evidence of the sustained and positive effects of EHT on the neurodevelopmental outcome and phenotypic presentation of boys with 47, XXY. The significant improvements in social and behavioral skills and executive functioning after EHT presented in this study support the need for continued research and earlier biological treatment interventions for 47, XXY boys.

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