Case Report: MECP2 and SH3KBP1 variants associated with autism spectrum disorder and immune dysregulation

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by impairments in social communication and restricted, repetitive behaviors. Increasing evidence suggests that immune dysregulation may be present in a subset of individuals with neurodevelopmental disorders, although its role in ASD remains incompletely understood. We report two male patients with ASD, neurodevelopmental delay, immune dysregulation, and congenital cardiac anomalies. Genetic analysis using chromosomal microarray (CMA) identified distinct copy number variants on the X chromosome in each case. In patient 1, a duplication of the Xq28 region encompassing the MECP2 gene was identified, consistent with MECP2 duplication syndrome, a well-established cause of neurodevelopmental impairment and recurrent infections. In this case, the clinical presentation was comparatively milder than typically described, highlighting phenotypic variability within this condition. In patient 2, a hemizygous deletion at Xp22.12 partially involving the SH3KBP1 gene was detected and classified as a variant of uncertain significance (VUS). The patient presented with recurrent respiratory infections, impaired humoral immune responses, reduced B-cell counts, and neurodevelopmental impairment. This observation broadens the limited clinical spectrum associated with SH3KBP1 variants and may aid future assessment of their clinical relevance, although a causal relationship remains unproven. Together, these observations emphasize the value of comprehensive genetic testing in individuals with complex neurodevelopmental and systemic presentations and support consideration of immunological evaluation in selected patients with ASD who present with recurrent infections, allergic disease, or additional phenotypic features suggestive of inborn errors of immunity.