Biallelic loss-of-function variants in NEMF cause central nervous system impairment and axonal polyneuropathy

Hum Genet. 2021 Apr;140(4):579-592. doi: 10.1007/s00439-020-02226-3. Epub 2020 Oct 13.

Abstract

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 the NEMF gene 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) of Nemf leads to impairment of axonal outgrowth and synapse development in cultured mouse primary cortical neurons. Our study demonstrates that disease-causing biallelic NEMF variants result in central nervous system impairment and other variable features. NEMF is an important player in mammalian neuron development.

MeSH terms

  • Adolescent
  • Adult
  • Alleles
  • Animals
  • Antigens, Neoplasm / genetics*
  • Axons*
  • Brain / metabolism
  • Cells, Cultured
  • Central Nervous System Diseases / genetics*
  • Consanguinity
  • Exome Sequencing
  • Female
  • Gene Expression Profiling
  • Genes, Recessive
  • Homozygote
  • Humans
  • Loss of Function Mutation*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Nucleocytoplasmic Transport Proteins / genetics*
  • Pedigree
  • Polyneuropathies / genetics*
  • RNA-Seq
  • Young Adult

Substances

  • Antigens, Neoplasm
  • NEMF protein, human
  • Nucleocytoplasmic Transport Proteins