1q21.1 Deletions

What does it mean to have a 1q21.1 deletion:

  • Genes provide our body’s instructions and are carried within structures called chromosomes. Sometimes individuals are born with extra or missing sections of chromosomes. A loss or gain of genetic material can impact health, learning, and behavior. The effects may vary based on the location and size of the changes, and the importance of genes there.
    • Individuals with 1q21.1 deletions are missing a specific section in one of their two chromosome 1's.
  • Individuals with 1q21.1 deletions appear to share an increased risk for developmental problems, which may or may not include autism. Depending on what genetic information is missing, this loss can impact a person’s health, learning and behavior. The information available about 1q21.1 deletions and duplications is limited and families and clinicians share a critical need for more information.

NEW: On June 11, 2015 a paper about individuals with 1q21.1 deletions and duplications was published in a medical journal called "Genetics in Medicine." Researchers used information collected through the Simons VIP Connect study to report new information about this genetic change (also called a "copy number variant.")

Read more about the article here: http://sfari.org/news-and-opinion/news/2015/diverse-features-found-for-autism-linked-chromosome-changes

Read the Simons VIP Summary here: VIP Summary #6: Clinical phenotype of the recurrent 1q21.1 copy-number variant

  • Children with the deletion tend to have...
    • a smaller-than-average head size
    • some degree of developmental delay
      • the most common feature is a fine motor delay or deficit; one example of this may be that people with a 1q21.1 deletion or duplication may take longer to insert a peg into a pegboard
      • the researchers also saw that people have some trouble understanding and articulating words
      • the majority of children have some level of cognitive challenge, but most people do not have intellectual disability
    • few child had a behavioral diagnosis like ADHD or autism
      • 2 of 19 kids in the study had a clinical diagnosis of autism
  • Importantly, the researchers didn't notice a distinct "pattern of features' or a "clinical picture," meaning, all of the kids with a 1q21.1 deletion were very different! There are a few key features shared by many of the 19 children studied by Raphael Bernier and his colleagues, but not a defined set of medical or behavioral concerns that doctors and parents can expect to see.

1q21.1 Deletions and Duplications Infographic

Download a .pdf copy

These resources all discuss Class 1 (distal) 1q21.1 deletions, as shown below.


For more detailed information, check out:



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