Autistic-like Behaviors Associated with a Novel Non-Canonical Splice-Site Variant: A Case Report of a Rare Clinical Syndrome.

Background. Heterozygous pathogenic variants in the DDX3X gene account for 1−3% of females with intellectual and developmental disabilities (IDD). The clinical presentation is variable, including a wide range of neurological and behavioral deficits and structural defects of the brain. Approximately 52% of affected females remain nonverbal after five years of age. Case presentation: We report a 7 year old nonverbal female with a likely novel de novo pathogenic heterozygous variant in the DDX3X gene affecting the non-canonical splice-site in the intron 1 (NM_001356:c.45+12G>A). The patient presents with features typical for the DDX3X phenotype, such as: movement disorders, behavioral problems, a diagnosis of autism spectrum disorder (ASD), and some other features uncommon for DDX3X such as: muscle hypertonia and spinal asymmetry evaluated through the scoliometer. Conclusions. Due to its rare occurrence, the clinical picture of DDX3X syndrome is yet to be fully determined. So far, behavioral disorders, including those from ASD, and neurological abnormalities seem to be the dominant features of this disorder.