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KAT6B gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

KAT6B gene

The KAT6B gene provides instructions for an enzyme that regulates gene activity during early development, and mutations in this gene are linked to several developmental syndromes and cancers.

Normal Function

The KAT6B gene provides instructions for making a histone acetyltransferase enzyme. These enzymes modify histones—structural proteins that bind to DNA and give chromosomes their shape. By adding an acetyl group to histones, these enzymes control the activity of certain genes. The enzyme produced by KAT6B is active throughout the body and appears to regulate genes important for the development of the skeleton and nervous system.

Health Conditions Related to Genetic Changes

Genitopatellar syndrome

Mutations in the KAT6B gene near the end of the gene (exon 18) cause genitopatellar syndrome. This condition is characterized by genital abnormalities, missing or underdeveloped kneecaps (patellae), intellectual disability, and other physical abnormalities. These mutations lead to a shortened enzyme that may function differently, altering gene regulation during development; these are described as "gain-of-function" mutations.

Ohdo syndrome, Say-Barber-Biesecker-Young-Simpson variant

Mutations throughout the KAT6B gene, including many in exon 18, cause the Say-Barber-Biesecker-Young-Simpson (SBBYS) variant of Ohdo syndrome. These mutations likely prevent the production of functional enzyme from one copy of the gene, leading to a "loss-of-function" that impairs gene regulation during early development.

Cancers and Tumors

Somatic genetic changes (acquired during a lifetime) involving KAT6B are associated with:

  • Acute myeloid leukemia (AML): A cancer of blood-forming cells.
  • Therapy-related myelodysplastic syndrome: A blood disorder that can occur after chemotherapy.
  • Uterine leiomyomas: Noncancerous growths in the uterus (uterine fibroids).

These changes often involve chromosomal translocations that disrupt the KAT6B gene, potentially impairing histone modification and allowing abnormal cells to divide uncontrollably.

Frequently Asked Questions

Most cases of KAT6B-related developmental syndromes, such as genitopatellar syndrome and Ohdo syndrome, are caused by de novo mutations. This means the genetic change occurs spontaneously in the egg or sperm cell, or very early in the embryo, and is not inherited from a parent. Consequently, these conditions often appear in families with no prior history of the disorder. However, in rare instances, a parent may carry the mutation with mild or undiagnosed symptoms, which can then be passed to the child.
In the context of cancer, KAT6B changes are somatic, meaning they occur in non-germline cells during a person's lifetime rather than being inherited. These changes often involve chromosomal translocations that disrupt the KAT6B gene. Since KAT6B regulates gene activity by modifying histones, its disruption can lead to abnormal cell division and growth. In acute myeloid leukemia, these genetic alterations can cause blood-forming cells in the bone marrow to become cancerous, leading to the production of abnormal white blood cells that crowd out healthy cells.
Parents and clinicians should look for a combination of skeletal and genital abnormalities. Key signs include missing or underdeveloped kneecaps (patellae), which may be detected during a physical exam or imaging. Genital abnormalities, such as undescended testicles in boys or labial fusion in girls, are also common. Additionally, developmental delays, particularly in speech and motor skills, and distinct facial features such as a broad nasal bridge or low-set ears, may be present. Early genetic testing is recommended if these specific physical traits are observed alongside developmental concerns.
The distinction often lies in the specific location and type of mutation within the KAT6B gene. Genitopatellar syndrome is typically caused by mutations in the final exon (exon 18) that result in a shortened but still partially functional enzyme, which is considered a gain-of-function change. In contrast, the Say-Barber-Biesecker-Young-Simpson variant is usually caused by mutations that prevent the production of a functional enzyme entirely, resulting in a loss-of-function. While both conditions share features like intellectual disability and skeletal abnormalities, the specific genetic mechanism influences the precise clinical presentation and severity.
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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