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NPM1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

NPM1 gene

The NPM1 gene provides instructions for making the nucleophosmin protein, which plays a critical role in cellular functions such as protein formation, DNA replication, and cell cycle progression.

Normal Function

The NPM1 gene provides instructions for making a protein called nucleophosmin, which is found in a small region inside the nucleus of the cell called the nucleolus. Nucleophosmin shuttles back and forth between the nucleus and the fluid surrounding it (the cytoplasm). It is thought to play a part in many cellular functions, including processes involved in protein formation, DNA replication, and the progression of the cell through the step-by-step process it takes to replicate itself (called the cell cycle). In the nucleolus, nucleophosmin attaches to another protein called ARF, keeping it in the proper location and protecting it from being broken down. The ARF protein is considered a tumor suppressor because it is involved in pathways that prevent cells from growing and dividing in an uncontrolled way.

Health Conditions Related to Genetic Changes

Acute promyelocytic leukemia

MedlinePlus Genetics provides information about Acute promyelocytic leukemia.

Cytogenetically normal acute myeloid leukemia

Mutations in the NPM1 gene are involved in a form of blood cell cancer known as cytogenetically normal acute myeloid leukemia (CN-AML). While large chromosomal abnormalities can be involved in the development of acute myeloid leukemia, about half of cases do not have these abnormalities; these are classified as CN-AML. Approximately 64 percent of people with CN-AML have a mutation in the NPM1 gene.

The NPM1 gene mutations involved in CN-AML are called somatic mutations; they are found only in cells that become cancerous and are not inherited. These mutations occur in a region of the gene designated exon 12. They change the blueprint used to make the nucleophosmin protein, leading to production of a protein with an altered sequence of protein building blocks (amino acids). The alterations change the amino acid tryptophan at protein position 290 and often the tryptophan at position 288. These two tryptophans are important for localization of the protein in the nucleolus. The new sequence also provides a signal (called the nuclear export signal) for the protein to be moved out of the nucleus. As a result, the nucleophosmin protein is found in the cytoplasm rather than the nucleolus.

It is not clear how abnormal localization of the nucleophosmin protein leads to acute myeloid leukemia. Research suggests that it affects the function of the ARF protein. Because of its interaction with the altered nucleophosmin, the ARF protein is also found in the cytoplasm in cells with these genetic changes. In addition, the altered nucleophosmin protein is unable to protect ARF from being broken down. A reduction of the tumor suppressor function of the ARF protein is believed to lead to the uncontrolled production of abnormal white blood cells that occurs in acute myeloid leukemia. Other effects of NPM1 gene mutations may also be involved in the development of leukemia.

Other cancers

A genetic rearrangement (translocation) involving the NPM1 gene is found in another blood cell cancer known as anaplastic large cell lymphoma (ALCL). In ALCL, white blood cells known as T cells grow and divide uncontrollably and often form tumors in the lymph nodes. The translocation involved in this cancer, known as t(2;5), fuses part of the NPM1 gene on chromosome 5 with part of another gene called ALK on chromosome 2. This rearrangement is a somatic mutation.

The protein produced from the fusion gene is called NPM-ALK. Like the normal activated ALK protein, NPM-ALK turns on signaling pathways that stimulate cell growth and division (proliferation) and maturation (differentiation). Unlike ALK, the NPM-ALK protein is active all the time, which causes uncontrolled cell proliferation and leads to ALCL.

Other Names for This Gene

  • B23
  • NPM
  • NPM_HUMAN
  • nucleolar protein NO38
  • nucleophosmin
  • nucleophosmin (nucleolar phosphoprotein B23, numatrin)
  • nucleophosmin/nucleoplasmin family, member 1

Frequently Asked Questions

mutation in the NPM1 gene is found in about 64% of cytogenetically normal AML cases and is generally associated with a favorable response to standard chemotherapy, especially when FLT3‑ITD is absent. Patients with an isolated NPM1 mutation often have higher remission rates and longer overall survival compared to those without the mutation.
NPM1 mutations in AML are somatic, meaning they arise only in the leukemia cells and are not inherited. Therefore, routine genetic testing of relatives is not indicated, and family members are not at increased risk because of this specific mutation.
Oncologists incorporate NPM1 status into risk stratification. If the mutation is present without a concurrent FLT3‑ITD high‑allele‑ratio mutation, many clinicians consider the patient “favorable risk” and may proceed with standard induction chemotherapy without immediate stem‑cell transplant. Conversely, if a high‑risk FLT3‑ITD is also present, the treatment plan may be intensified.
fter achieving remission, bone‑marrow or peripheral‑blood samples are often examined for minimal residual disease (MRD) using sensitive PCR assays that detect the NPM1 mutation. Detecting MRD can predict relapse earlier than morphology alone, so many centers perform this test at the end of consolidation therapy and then periodically (e.g., every 3–6 months) during remission.
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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