Pathogenic nonsense variant in NFIB in another patient with dysmorphism, Autism Spectrum Disorder, agenesis of the corpus callosum, and intellectual disability.

The Nuclear Factor I (NFI) transcription family (NFIA, NFIB and NFIX) have been implicated in a range of developmental pathologies, including corpus callosum, craniofacial, urinary tract abnormalities, as well in the development of a number of neurodevelopmental developmental phenotypes including muscular hypotonia, motor and speech delay, attention deficit disorder, autism spectrum disorder, and behavioural abnormalities. NFIB haploinsufficiency has only recently been presented as a cause for macrocephaly-intellectual disability syndrome, with comparable phenotypes to NFIA related disorder. We add another patient with a previously reported nonsense variant in the NFIB who has Autism Spectrum Disorder level 2, agenesis of the corpus callosum, ADHD, obsessive compulsive Disorder and an intellectual disability. A clinical exome analysis identified a nonsense variant, c.265C > T, p.(Arg89*) involving exon 2 of NFIB (ClinVar variation ID: 424,344). A brain MRI demonstrated agenesis of the corpus callosum.