Deletion of FMR1 results in sex-specific changes in behavior.

Fragile X Syndrome (FXS) is a neurodevelopmental disorder caused by excessive trinucleotide (CGG) repeats in the FMR1 gene coding for fragile x mental retardation protein (FMRP). In humans, this disorder is characterized by intellectual disability, as well as other behavioral abnormalities, such as hyperactivity and social behavior abnormalities. Mutations in the FMR1 gene are found in 2 - 6 % of individuals with Autism Spectrum Disorder (ASD), making it the single largest genetic contributor to ASD. Mouse models of FXS disorder are commonly touted as preferred models for understanding ASD. Furthermore, few studies to date have examined the role of sex in the FMR1 phenotype. In the present study, we used a systemic FMR1 knockout in an FVB background strain. We examined the effects of this genetic mutation in males and females homozygous for an FMR1 mutation on measures sociability, repetitive behaviors, vocalization patterns, anxiety and fear-related learning.