Trisomy 1q


What is trisomy 1q?

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differs between males and females and determine our gender. Each of these chromosomes has 2 parts, called the long arm and the short arm. The long arm is referred to as "q" and the short arm is abbreviated "p". Both arms of all chromosomes are further divided into light and dark colored bands that are labeled by numbers. The further away from the centromere (connecting part between p and q arm) the higher the number. The labeled bands help everyone stay consistent in discussed specific parts of the chromosome.

In trisomy 1q, some or all of the cells in the body have extra parts of the long arm of chromosome 1. Cells of the body are called "trisomic" when they have an extra chromosome 1q. When only some cells of the body have an extra 1q and others do not. This is called "mosaic".

An extra chromosome 1q can cause a range of health and developmental problems. The severity of problems depend on how much and what parts of the chromosome are duplicated. Some individuals have developmental delay, intellectual disability, birth defects and unique facial features. Depending on the extent of the duplication, affected pregnancies could be miscarried or infants could pass away shortly after birth. If only small amounts of the chromosome are duplicated, then the infant/child may be more mildly affected. This is a very diverse condition whose features are very dependent on what parts of the 1q chromosome are extra.

Unique - the support group for Rare Chromosome Disease - has a brochure publication from 2005 discussing some common features in children who have Chromosome 1q duplications. It is separated out by what parts and how much of the q arm is duplicated. While it is helpful to read what other children with these duplications have, it is important to understand the exact location and amount of duplicated information make big differences of what a family could expect. The brochure can be accessed here. This brochure also has a great picture of the q arm of Chromosome 1q to better understand the numbering system.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • • DATE UPDATED: 2016-06-08


“Chromosome 1q Duplication” Genetic and Rare Disease Information Center.

"Duplication 1q" Unique Publication. 2005.

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