CIZ1-LOSS CAUSES FEMALE-SPECIFIC AUTOSOMAL NEURODEVELOPMENTAL DISORDER THROUGH DEFECTIVE X-INACTIVATION MAINTENANCE

We report an autosomal recessive neurodevelopmental disorder exclusively affecting females carrying biallelic loss-of-function variants in CIZ1, a gene encoding a nuclear matrix protein essential for the maintenance of X-chromosome inactivation. Eight unrelated affected females were identified, whereas male siblings with biallelic variants were asymptomatic. We showed that loss of CIZ1 compromises the maintenance of X-chromosome inactivation, leading to an abnormal overexpression of a subset of X-linked genes.