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Genetic and Rare Diseases Information Center (GARD)

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Chromosome 1q21.1 duplication syndrome


Other Names for this Disease

  • 1q21.1 microduplication syndrome
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Overview

What is chromosome 1q21.1 duplication syndrome?

What causes chromosome 1q21.1 duplication syndrome?

What is chromosome 1q21.1 duplication syndrome?

Chromosome 1q21.1 duplication syndrome is a rare condition caused by the presence of an extra copy of a small piece of chromosome 1 in the cells of the body. Signs and symptoms can vary widely among affected individuals. Some individuals have no symptoms, while others may have features such as a large head size (macrocephaly); mild to moderate developmental delay and learning difficulties; autism or autistic-like behavior; heart problems; seizures; and/or and distinctive facial features.[1][2] This condition can occur sporadically as a de novo mutation (by chance) or can be inherited in an autosomal dominant manner from a parent. Treatment depends on the signs and symptoms present in each individual.
Last updated: 8/15/2013

What causes chromosome 1q21.1 duplication syndrome?

Chromosome 1q21.1 duplication syndrome can occur sporadically (by chance) from a de novo mutation or can be inherited in an autosomal dominant manner from a parent that has the same duplication. When the condition occurs sporadically, it is caused by a random error during the formation of the egg or sperm cell, or during the early days after fertilization.[2] The duplication occurs when part of chromosome 1 is copied (duplicated) abnormally, resulting in the extra genetic material from the duplicated segment.[3] If the condition is inherited from a parent, it means that one of the parents also has the extra piece of genetic material. In these cases, the parent with the duplication has a 50% chance with each pregnancy to pass the duplication on to his/her child. The only way to know if it has been inherited from a parent is for the parents to have genetic testing. A parent with the duplication may not have any signs or symptoms. In both cases, nothing that either parent does, or does not do, can cause this syndrome to occur.

Individuals who are interested in genetic testing for themselves or family members should speak with a genetics professional.
Last updated: 8/15/2013

References
  1. Hamoush A. Chromosome 1q21.1 duplication syndrome. OMIM. June 10, 2009; http://www.ncbi.nlm.nih.gov/omim/612475. Accessed 11/4/2010.
  2. 1q21.1 Microduplications. Unique. June 2011; http://www.rarechromo.org/information/Chromosome%20%201/1q21.1%20microduplications%20FTNW.pdf. Accessed 8/15/2013.
  3. Chromosomal duplication. Genetics Home Reference. August 12, 2013; http://ghr.nlm.nih.gov/handbook/illustrations/chromosomalduplication. Accessed 8/15/2013.


Other Names for this Disease
  • 1q21.1 microduplication syndrome
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.