CHAMP1 premature termination codon mutations found in individuals with intellectual disability cause a homologous recombination defect through haploinsufficiency.

CHAMP1 (chromosome alignment-maintaining phosphoprotein 1) plays a role in the repair of DNA double-strand breaks (DSBs) by homologous recombination (HR). The CHAMP1 gene is one of the genes mutated in individuals with intellectual disability. The majority of the mutations are premature termination codon (PTC) mutations, while missense mutations have also been reported.