NFIA-Related Disorder

Excerpt

Clinical characteristics: 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.

Diagnosis/testing: The diagnosis of NFIA-related disorder is established in a proband by detection of one of the following: a heterozygous intragenic NFIA pathogenic variant; a heterozygous deletion of the 1p31.3 region that includes part or all of NFIA with surrounding genes intact; or a chromosome translocation/other rearrangement with a 1p31.3 breakpoint that disrupts NFIA.

Management: Treatment of manifestations: Standard treatment of seizure disorder, tethered spinal cord, recurrent urinary tract infections, hydronephrosis, strabismus, craniosynostosis, and developmental delays.

Surveillance: Affected individuals should be followed by the appropriate specialists (e.g., neurologist, urologist, and/or clinical geneticist) as needed based on their particular features.

Genetic counseling: NFIA-related disorder is inherited in an autosomal dominant manner. Each child of an individual with NFIA-related disorder has a 50% chance of inheriting the causative genetic alteration. The proportion of NFIA-related disorder caused by de novo variants is approximately 75%-80%. Prenatal diagnosis for a pregnancy at increased risk is possible if the causative genetic alteration in an affected family member is known.