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KLLN gene

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

KLLN gene

The KLLN gene provides instructions for making the killin protein, which acts as a tumor suppressor by regulating cell division and maintaining genetic stability.

Normal Function

The KLLN gene provides instructions for making a protein called killin. The activity of the KLLN gene is controlled by a protein called p53 (which is produced from the TP53 gene). Little is known about the function of killin, although it is thought to trigger cells to self-destruct (undergo apoptosis) when they are damaged or no longer needed. In this way, killin helps to prevent abnormal cells from growing and dividing unchecked to form tumors. Through its role in regulating cell division, killin helps maintain the stability of a cell's genetic information. Based on these roles, killin is thought to be a tumor suppressor.

Health Conditions Related to Genetic Changes

Cowden syndrome

Some cases of Cowden syndrome and a similar condition called Cowden-like syndrome result from a change involving the KLLN gene. These conditions are characterized by multiple tumor-like growths called hamartomas and an increased risk of developing certain cancers. When Cowden syndrome and Cowden-like syndrome are caused by KLLN gene mutations, the conditions are associated with a particularly high risk of developing breast and kidney cancers.

The genetic change associated with these conditions is known as promoter hypermethylation. The promoter is a region of DNA near the gene that controls gene activity (expression). Hypermethylation occurs when too many small molecules called methyl groups are attached to the promoter region. The extra methyl groups reduce the expression of the KLLN gene, which means that less killin is produced. A reduced amount of killin may allow abnormal cells to survive and proliferate inappropriately, which can lead to the formation of tumors.

The promoter region of the KLLN gene is shared with another gene, PTEN. The single promoter controls the expression of both genes. However, specific hypermethylation of the KLLN gene promoter only affects the expression of the KLLN gene; people with this type of genetic change have normal expression of the PTEN gene. Other types of mutations in the PTEN gene can cause Cowden syndrome and Cowden-like syndrome.

Other Names for This Gene

  • KILIN_HUMAN
  • KILLIN
  • killin
  • killin, p53-regulated DNA replication inhibitor

Frequently Asked Questions

Mutations that hypermethylate the KLLN promoter reduce killin production, which is thought to increase the risk of hamartomas and certain cancers, particularly breast and kidney cancers, in individuals with Cowden or Cowden‑like syndrome.
The test is a DNA methylation assay performed on a blood sample. It is considered when a patient has clinical features of Cowden syndrome but no pathogenic variants in the more common PTEN gene, or when there is a strong family history of related cancers.
Patients should follow intensified surveillance: annual breast MRI and mammography starting at age 30, colonoscopy every 1–2 years starting at age 35, and renal imaging (ultrasound or MRI) every 1–2 years. Prophylactic mastectomy or nephrectomy may be discussed in high‑risk cases.
While genetics play a major role, maintaining a healthy weight, limiting alcohol, avoiding tobacco, and ensuring adequate vitamin D and calcium intake can support overall health. Regular exercise and a balanced diet may also help reduce inflammation and support immune function, though they cannot replace formal surveillance.
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.