For the purposes of this chapter, NFIA-related disorder is defined as heterozygous inactivation or disruption of only NFIA without involvement of adjacent or surrounding genes. NFIA-related disorder comprises central nervous system abnormalities (most commonly abnormalities of the corpus callosum) with or without urinary tract defects, such as unilateral or bilateral vesicoureteral reflux and hydronephrosis. Additional features include macrocephaly, seizures, developmental delay and/or cognitive impairment, nonspecific dysmorphic features, ventriculomegaly, and hypotonia, which can exacerbate motor delay and feeding issues in infancy. Rarer features may include strabismus, cutis marmorata, or craniosynostosis of the metopic, lambdoid, or sagittal suture. [from GeneReviews]