title: Unmasking a novel disease gene NEO1 associated with autism spectrum disorders by a hemizygous deletion on chromosome 15 and a functional polymorphism.
abstract: BACKGROUND
  Autism spectrum disorders (ASD) are neurodevelopmental disorders with a high degree of heritability, but the genetic basis is exceedingly heterogeneous. Microdeletions of chromosome 15q24 have been demonstrated to be recurrent genomic alterations in ASD patients. Of interest, neuronal migration genes are of particular relevance to the pathogenesis of ASD. NEO1 is located in 15q24 and encodes for neogenin, a membrane receptor involved in cortical interneuron migration and axon guidance. We postulated that the ASD patient has one copy of the NEO1 gene deleted and the other copy disrupted by intragenic mutation.
  
  
  RESULTS
  We identify genetic changes in both alleles of NEO1 in two individuals from a cohort of 66 Han Chinese patients with ASD. In one patient, we detected a hemizygous 1.97-Mb deletion at 15q23q24.1 encompassing the NEO1 gene, a missense variant in NEO1, c.3388C>T (p.Arg1130Cys), and a duplication, c.2204-14_2204-2dup, in the acceptor splice site of intron 14 of NEO1. Furthermore, we identified a second patient was a compound heterozygote for NEO1. A novel missense variant in NEO1, c.302G>A (p.Arg101His), in addition to c.3388C>T and c.2204-14_2204-2dup was detected in the second patient. The c.3388C>T is a single nucleotide polymorphism with allele frequency of 0.045 in Han Chinese individuals. In silico and functional analyses indicated that p.Arg1130Cys, located at the nuclear localization signal (NLS) domain of neogenin led to defective nuclear translocation of neogenin.
  
  
  CONCLUSIONS
  The hemizygous 15q deletion unmasks the recessive functional polymorphism in NEO1 which plays a pivotal role in cortical interneuron development. Our study provides the first evidence linking NEO1 with ASD in humans.
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, China; Kowloon West Cluster Laboratory Genetics Service, Department of Pathology, Princess Margaret Hospital, Hong Kong, China.
authors.forename: Wai-Kwan
authors.initials: WK
authors.lastname: Siu
authors.affiliation: Department of Pathology, The University of Hong Kong, Hong Kong, China. Electronic address: ching-wanlam@pathology.hku.hk.
authors.forename: Ching-Wan
authors.initials: CW
authors.lastname: Lam
authors.affiliation: School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Gao
authors.affiliation: School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.
authors.forename: Hei-Man
authors.initials: HM
authors.lastname: Vincent Tang
authors.affiliation: School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.
authors.forename: Dong-Yan
authors.initials: DY
authors.lastname: Jin
authors.affiliation: Kowloon West Cluster Laboratory Genetics Service, Department of Pathology, Princess Margaret Hospital, Hong Kong, China.
authors.forename: Chloe Miu
authors.initials: CM
authors.lastname: Mak
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics; D000067877:Autism Spectrum Disorder / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002681:China; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D005808:Genes, Recessive; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: C000611758:NEO1 protein, human; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface
keywords: Autism spectrum disorders; Functional polymorphism; NEO1