Abstract
BACKGROUND: Duplications involving Xp22.33, particularly within the pseudoautosomal region 1 (PAR1), are rare. While copy number variants (CNVs) involving SHOX, a dosage-sensitive gene in PAR1, are known to cause growth disorders, large duplications encompassing the entire PAR1 region and beyond show variable associations with skeletal and neurodevelopmental abnormalities. Duplication of the near-complete, isolated PAR1 with a comprehensive clinical description has not been reported. CASE PRESENTATION: We report a male patient with a 2.49 Mb duplication encompassing nearly the entire PAR1 region (chrX:200854-2692897, GRCh37). Clinical features included global developmental delay (GDD), autism spectrum disorder (ASD), recurrent seizures, hypotonia with joint hypermobility, dysmorphic features, and proportionate tall stature. The duplicated segment contains 30 genes, including 15 protein-coding genes that escape X-inactivation. Among these, SHOX, DHRSX, ASMT, and CSF2RA are notable candidates contributing to the observed phenotype. CONCLUSIONS: This report presents a detailed clinical characterization of a rare, near-complete, isolated PAR1 duplication in a male individual. The co-occurrence of tall stature, GDD, ASD, and seizures raises the possibility of a dosage-related phenotypic effect involving one or more genes within the duplicated interval. While causality cannot be definitively established, these observations contribute to the emerging understanding of the functional consequences of Xp22.33 duplications and suggest that increased copy number within this region may be associated with a clinically significant neurodevelopmental phenotype.