Novel biallelic multi-exon duplication in the PIGN gene associated with multiple congenital anomalies–hypotonia–seizures syndrome 1

Multiple congenital anomalies–hypotonia–seizures syndrome type 1 (MCAHS1) is a rare autosomal recessive disorder caused by PIGN variants affecting glycosylphosphatidylinositol (GPI) anchor biosynthesis. Exon-level duplications are exceptionally uncommon. We describe a male neonate with multiple congenital anomalies, including auricular malformation, submucous cleft palate, accessory nipple, cryptorchidism, microphallus, clubfoot, and digital hypoplasia, accompanied by hypotonia and poor sucking. Whole-exome trio sequencing identified a biallelic duplication spanning exons 4–22 of PIGN , with an apparent four-copy state in the proband. This report expands the mutational spectrum of PIGN -related disorders and emphasizes the diagnostic value of trio-based exome sequencing in neonates with multiple congenital anomalies and hypotonia.