Biallelic loss-of-function variants inNEMFcause central nervous system impairment and axonal polyneuropathy

We aimed to detect the causative gene in five unrelated families with recessive inheritance pattern neurological disorders involving the central nervous system, and the potential function of theNEMFgene in the central nervous system. Exome sequencing (ES) was applied to all families and linkage analysis was performed on family 1. A minigene assay was used to validate the splicing effect of the relevant discovered variants. Immunofluorescence (IF) experiment was performed to investigate the role of the causative gene in neuron development. The large consanguineous family confirms the phenotype-causative relationship with homozygous frameshift variant (NM_004713.6:c.2618del) as revealed by ES. Linkage analysis of the family showed a significant single-point LOD of 4.5 locus. Through collaboration in GeneMatcher, four additional unrelated families' likely pathogenic NEMF variants for a spectrum of central neurological disorders, two homozygous splice-site variants (NM_004713.6:c.574+1G>T and NM_004713.6:c.807-2A>C) and a homozygous frameshift variant (NM_004713.6: c.1234_1235insC) were subsequently identified and segregated with all affected individuals. We further revealed that knockdown (KD) ofNemfleads to impairment of axonal outgrowth and synapse development in cultured mouse primary cortical neurons. Our study demonstrates that disease-causing biallelicNEMFvariants result in central nervous system impairment and other variable features.NEMFis an important player in mammalian neuron development.

Automated summary

This study identified causative gene variants related to central nervous system disorders, particularly focusing on the NEMF gene's function in neuron development. Through various analyses, it was found that biallelic NEMF variants can result in impaired axonal outgrowth and synapse development in neurons. Additionally, other pathogenic variants of NEMF were identified, further emphasizing the gene's importance in mammalian neuron development.