PNKP and Intellectual disability: More recently, in 2025, Xie et al. [23] and Sorrentino et al. [24] further expanded the genetic landscape of PNKP variants, linking the homozygous c.976G>A (p.Glu326Lys) and the homozygous splicing variant c.1448+1G>A to microcephaly, intellectual disability, and complex neurological phenotypes.