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last update : 30-05-2012
Symbol DEL17Q21
Location 17q21.31
Name chromosome 17q21.31 microdeletion syndrome
Other name(s) KANSL1-Related Intellectual Disability Syndrome; monosomy 17q21
Corresponding gene MAPT , CRHR1 , KANSL1
Main clinical features
  • characteristic facial features: long face, tubular or pear-shaped nose with bulbous tip, friendly/amiable behavior
  • low birth weigtht (<3rd centile), neonatal hypotonia, feeding problems in infants, developmental delay/mental retardation
  • easily controlled seizures, heart defects and kidney/urologic anomalies
  • ectodermal structures (skin, hair and teeth) frequently affected
  • two families with sibling recurrence due to low-grade mosaicism, PMID: 22293690
  • Genetic determination chromosomal
    genomic disorder
    Prevalence 1 in 16 000 births
    Function/system disorder multisystem/generalized
    mental retardation
    Type MCA/MR
    Gene product
    Name the KANSL1 protein is an evolutionarily conserved regulator of the chromatin modifier KAT8, which influences gene expression through histone H4 lysine 16 (H4K16) acetylation
    Gene mutationChromosome rearrangementEffectComments
      deletion haploinsufficiency microdeletion with a critical region of 424kb
    various types   haploinsufficiency in the KANSL1 gene PMID: 22544367, PMID: 22544363
    Remark(s) several low-copy repeats, recently associated with a 900 kb inversion present in up to 20 percent of European subjects, are present in 17q21.31; this inversion is present in all examined parent originating the deletion ; the deleted region contains the MAPT gene, implicated in late onset neurodegenerative disorders, and other genes; haploinsufficiency of KANSL1 is sufficient to cause the classical 17q21.31 microdeletion syndrome phenotype PMID: 22544367,, PMID: 22544363 ;
    Genotype/Phenotype correlations patients carrying larger or non-overlapping deletions in this region have also been described with different manifestations