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Chromosome 17
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Chromosome

Chromosome 17

Chromosome 17, one of the 23 pairs of human chromosomes, contains 1,200 to 1,300 genes, and alterations to its structure or number are associated with a range of health conditions.

Overview

Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 17, one copy inherited from each parent, form one of the pairs. Chromosome 17 spans about 83 million DNA building blocks (base pairs) and represents between 2.5 and 3 percent of the total DNA in cells.

Identifying the 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 17 likely contains 1,200 to 1,300 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 17.

17q12 deletion syndrome

17q12 deletion syndrome is a condition that results from the deletion of a small piece of chromosome 17 in each cell. Signs and symptoms of 17q12 deletion syndrome can include abnormalities of the kidneys and urinary system, a form of diabetes called maturity-onset diabetes of the young type 5 (MODY5), developmental delays, intellectual disabilities, and behavioral or psychiatric disorders. Some people with this chromosomal change have Mayer-Rokitansky-Küster-Hauser syndrome, which is characterized by the underdevelopment or absence of the vagina and uterus. The features that are associated with 17q12 deletion syndrome vary widely, even among affected members of the same family.

Most people with 17q12 deletion syndrome are missing about 1.4 million base pairs (1.4 megabases or Mb), on the long (q) arm of the chromosome at a position designated q12. This is the same region of chromosome 17 that is abnormally copied (duplicated) in people with a 17q12 duplication (described below). This chromosome segment is prone to rearrangement during cell division.

The segment that is most often deleted in people with 17q12 deletion syndrome includes 15 genes. Some of the features associated with the condition likely result from the loss of two of these genes, HNF1B and LHX1. Studies suggest that the loss of one copy of the HNF1B gene in each cell causes kidney and urinary tract abnormalities and diabetes. Missing one copy of LHX1 is thought to contribute to intellectual disabilities, behavioral and psychiatric conditions, and Mayer-Rokitansky-Küster-Hauser syndrome. The loss of other genes in the deleted region may also influence the signs and symptoms that can occur in people with 17q12 deletion syndrome.

17q12 duplication

17q12 duplication is a chromosomal change in which a small piece of chromosome 17 is abnormally duplicated. This duplication can cause a variety of signs and symptoms, even among members of the same family. Some individuals with the duplication have no apparent signs or symptoms, or they have features that are very mild. Other individuals can have intellectual disabilities, developmental delays, and a wide range of physical abnormalities.

Most people with 17q12 duplications have an extra copy of about 1.4 Mb of DNA at position q12 on chromosome 17. It is the same region of chromosome 17 that is deleted in people with 17q12 deletion syndrome.

The duplicated segment of 17q12 includes at least 15 genes. Because some people with this duplication have no obvious signs or symptoms, researchers suspect that additional genetic factors may play a role.

Acute promyelocytic leukemia

A type of blood cancer known as acute promyelocytic leukemia is caused by a rearrangement (translocation (t(15;17))) of genetic material between chromosomes 15 and 17. This translocation fuses part of the PML gene from chromosome 15 with part of the RARA gene from chromosome 17. This genetic change is somatic, which means it is acquired during a person's lifetime and is present only in certain cells.

The t(15;17) translocation is called a balanced reciprocal translocation because the pieces of chromosome are exchanged with each other and no genetic material is gained or lost. The protein produced from this fused gene is known as PML-RARα.

The PML-RARα protein functions differently than the proteins produced from the normal PML and RARA genes. The RARA gene on chromosome 17 provides instructions for making a transcription factor called the retinoic acid receptor alpha (RARα). A transcription factor is a protein that binds to specific regions of DNA and helps control the activity (transcription) of particular genes.

Normally, the RARα protein controls the activity of genes that are important for

Frequently Asked Questions

17q12 deletion syndrome is often a de novo (new) mutation, meaning it occurs spontaneously in the affected individual and is not inherited from a parent. However, it can also be inherited in an autosomal dominant pattern, meaning only one copy of the altered chromosome 17 is needed to cause the condition. If a parent has the deletion, there is a 50% chance with each pregnancy that their child will inherit it. Genetic counseling and testing for parents can help determine the risk of recurrence in a family.
Diagnosis usually involves genetic testing, such as chromosomal microarray analysis (CMA) or fluorescence in situ hybridization (FISH), which can detect the small missing piece of chromosome 17. Because symptoms vary widely, diagnosis often occurs after a person presents with a combination of features like kidney abnormalities, developmental delays, or a diagnosis of MODY5 diabetes, prompting genetic evaluation.
Management is multidisciplinary and tailored to the individual's specific symptoms. This often includes regular monitoring of kidney function, management of diabetes (if present), developmental therapies (physical, occupational, speech), educational support for intellectual disabilities, and psychiatric care for behavioral issues. For females with Mayer-Rokitansky-Küster-Hauser syndrome, gynecological care and potential reconstructive surgery may be necessary.
MODY5 (Maturity-Onset Diabetes of the Young type 5) is a specific form of diabetes caused by the deletion of the HNF1B gene within the 17q12 region, leading to impaired insulin production and often kidney problems. It is managed with diet, medication, or insulin, similar to other forms of diabetes, but with careful attention to kidney health. Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, also linked to the 17q12 deletion, involves the underdevelopment or absence of the vagina and uterus. Management typically includes psychological support, gynecological care, and may involve surgical creation of a vagina (vaginoplasty) for sexual function, though fertility is generally not possible due to the absent uterus.
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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