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GENATLAS PHENOTYPE
last update : 23-01-2018
Symbol DEL15Q13
Location 15q13.3
Name chromosome 15q13.3 microdeletion
Other name(s) monosomy 15q13.3
Corresponding gene CHRNA7
Main clinical features
  • incomplete penetrance/variable expressivity with highly variable intra- and inter-familial phenotype
  • mild to moderate mental retardation
  • epilepsy and/or abnormal EEG findings
  • mild facial dysmorphism : hypertelorism, upslanting palpebral fissures, prominent philtrum with full everted lips
  • minor skeletal and/or joints defects of the hand
  • absence epilepsy accompanied by intellectual disability may represent a common phenotype, PMID: 22050399
  • Genetic determination chromosomal
    genomic disorder
    Prevalence . ~0.3 percent in MR or autism, ~0.2 percent in schizophrenia, 1 percent in IGE patients . approximately 25 percent of 15q13.3
    Related entries DUP15Q13
    Function/system disorder psychiatry disorder
    mental retardation
    Type MCA/MR
    Gene product
    Name CHRNA7 encodes a synaptic ion channel protein mediating neuronal signal transmission and has been suggested to be a possible candidate gene in the pathogenesis of epilepsy, schizophrenia, and bipolar disorder
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
      deletion   recurrent deletion between BP4 and BP5 (1.5 Mb), or BP3 and BP5(3.95 Mb)
      deletion   an homozygous microdeletion associated with a severe neurodevelopmental disorder (LePichon 2010)
      deletion   small deletions including only the CHRNA7 gene, PMID: 22775350
    Remark(s) most prevalent known genetic risk factor for epilepsia (Mefford, 2009); inversion polymorphism between BP4 and BP5 in the normal population
    Genotype/Phenotype correlations reciprocal duplication events between BP4-BP5 or BP3-BP4 may represent benign CNV or are associated with milder phenotypic abnormalities; for the IGE component of the phenotype in multiplex families the odds ratio is 68 (95% confidence interval 29-181), indicating a pathogenic lesion predisposing to epilepsy with complex inheritance and incomplete penetrance (Dibbens,2009); homozygous 15q13.3 microdeletion with a complex neurodevelopmental disorder characterized by severe visual impairment, hypotonia, profound intellectual disability, and refractory epilepsy (LePichon 2010)