Variants in nuclear factor I genes influence growth and development.

Area of Science:

• Genetics
• Neuroscience
• Developmental Biology

Background:

• Nuclear Factor One (NFI) proteins are transcription factors vital for organ system development, particularly the brain.
• Overlapping expression and knockout phenotypes of Nfia, Nfib, and Nfix in mice suggest shared roles in brain development.
• Human haploinsufficiency of NFIA, NFIB, and NFIX presents with overlapping neurodevelopmental deficits, macrocephaly, and brain anomalies.

Purpose of the Study:

• To explore the overlapping functions and distinct clinical manifestations of NFI gene variants in human neurodevelopmental disorders.
• To highlight the clinical relevance of considering NFI gene variants in individuals with intellectual disability and brain overgrowth.

Main Methods:

• Review of existing literature and clinical data on human phenotypes associated with NFIA, NFIB, and NFIX gene variants.
• Comparative analysis of mouse models and human conditions to understand gene function and phenotypic overlap.
• Clinical characterization of distinct NFI-related disorders, including Marshall-Smith syndrome and NFIX duplication phenotypes.

Main Results:

• Haploinsufficiency of NFIA, NFIB, and NFIX leads to shared neurodevelopmental deficits, macrocephaly, and brain anomalies.
• Specific NFIX variants acting in a dominant-negative manner cause Marshall-Smith syndrome, characterized by severe cognitive impairment and bone dysplasia.
• NFIX duplications result in phenotypes opposite to haploinsufficiency, including short stature and microcephaly.

Conclusions:

• NFI genes play critical, partially overlapping roles in human brain development.
• Genetic testing for NFI variants should be considered in patients with unexplained intellectual disability and brain overgrowth.
• Distinct clinical features aid in differentiating between various NFI-related disorders, expanding the spectrum of known genetic conditions.