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Chromosome 7
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Chromosome

Chromosome 7

Chromosome 7 is one of the 23 pairs of human chromosomes, spanning about 159 million DNA base pairs and containing 900 to 1,000 genes, with various structural or numerical changes linked to conditions such as 7q11.23 duplication syndrome, Williams syndrome, and certain cancers.

Overview

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 7, one copy inherited from each parent, form one of the pairs. Chromosome 7 spans about 159 million DNA building blocks (base pairs) and represents more than 5 percent of the total DNA in cells.

Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 7 likely contains 900 to 1,000 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.

Health Conditions Related to Chromosomal Changes

The following chromosomal conditions are associated with changes in the structure or number of copies of chromosome 7.

7q11.23 duplication syndrome

7q11.23 duplication syndrome, a condition that can cause a variety of neurological and behavioral problems, is a result of an extra copy of a region on the long (q) arm of chromosome 7. This region is called the Williams-Beuren syndrome critical region (WBSCR) because its deletion causes a disorder called Williams syndrome (described below), also known as Williams-Beuren syndrome. The region, which is 1.5 to 1.8 million DNA base pairs (Mb) in length, includes 25 to 27 genes.

Extra copies of several

Frequently Asked Questions

While both involve the 7q11.23 region, Williams syndrome (a deletion) typically presents with an overly friendly personality, specific facial features, cardiovascular problems, and mild to moderate intellectual disability. In contrast, 7q11.23 duplication syndrome often leads to developmental delays, autism spectrum disorder, anxiety, and speech difficulties, with individuals tending to be more introverted or shy.
Both 7q11.23 duplication syndrome and Williams syndrome are most often caused by a de novo (new) genetic change that occurs spontaneously during the formation of reproductive cells or early fetal development, meaning they are not inherited from a parent. However, there are rare instances where a parent might carry a balanced chromosomal rearrangement that increases the risk of passing on an unbalanced deletion or duplication.
These conditions are usually diagnosed through genetic testing. A chromosomal microarray (CMA) or FISH (fluorescence in situ hybridization) test can detect the specific deletion or duplication in the 7q11.23 region. This testing is often performed after a child presents with characteristic developmental or physical features.
Management for 7q11.23 duplication syndrome is typically multidisciplinary and focuses on early intervention. This often includes speech therapy for communication difficulties, occupational therapy for fine motor skills, physical therapy for gross motor delays, and behavioral therapy to address social and anxiety issues. Educational support tailored to their learning style is also crucial.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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