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Genetic and Rare Diseases Information Center (GARD)

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1q21.1 microdeletion syndrome

Other Names for this Disease
  • 1q21.1 microdeletion
  • Chromosome 1q21.1 microdeletion syndrome
  • Monosomy 1q21.1
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1q21.1 microdeletion syndrome is a newly described chromosome abnormality where a segment of genetic material on the long arm (or q arm) of chromosome 1 at position 21.1 is missing (or deleted). It has been described in 46 patients to date. Some people with this deletion have no observable features; while others have variable features that can include small head, developmental delay (speech and motor delays), mild intellectual disability, distinctive facial features, and eye abnormalities. Other findings can include seizures as well as abnormalities of the heart, skeleton, and urinary system. Psychiatric and behavioral features can include autism spectrum disorders, schizophrenia, attention deficit hyperactivity disorder and sleep disorders. This syndrome is caused by a deletion in a specific region of 1q21.1, which is distinct from the deletion region that causes TAR syndrome.[1][2]
Last updated: 8/8/2011


  1. 1q21.1 microdeletion syndrome. Orphanet. March 2011; Accessed 8/8/2011.
  2. Haldeman-Englert C & Jewett T. 1q21.1 Microdeletion. GeneReviews. February 2011; Accessed 8/8/2011.
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Basic Information

  • Genetics Home Reference (GHR) contains information on 1q21.1 microdeletion syndrome. This website is maintained by the National Library of Medicine.
  • Unique is a source of information and support to families and individuals affected by rare chromosome disorders. Click on the link to view information about 1q21.1 microdeletion syndrome.

In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.