Neuroligins are post-synaptic, cellular adhesion molecules implicated in synaptic formation and function. NLGN2 is strongly linked to inhibitory, GABAergic signaling and is crucial for maintaining the excitation-inhibition balance in the brain. Disruption of the excitation-inhibition balance is associated with neuropsychiatric disease. In animal models, altered NLGN2 expression causes anxiety, developmental delay, motor discoordination, social impairment, aggression, and sensory processing defects. In humans, mutations in NLGN3 and NLGN4 are linked to autism and schizophrenia; NLGN2 missense variants are implicated in schizophrenia. Copy number variants encompassing NLGN2 on 17p13.1 are associated with autism, intellectual disability, metabolic syndrome, diabetes, and dysmorphic features, but an isolated NLGN2 nonsense variant has not yet been described in humans. Here, we describe a 15-year-old male with severe anxiety, obsessive-compulsive behaviors, developmental delay, autism, obesity, macrocephaly, and some dysmorphic features. Exome sequencing identified a heterozygous, de novo, c.441C>A p.(Tyr147Ter) variant in NLGN2 that is predicted to cause loss of normal protein function. This is the first report of an NLGN2 nonsense variant in humans, adding to the accumulating evidence that links synaptic proteins with a spectrum of neurodevelopmental phenotypes.
- synaptic function