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HNRNPK gene

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

HNRNPK gene

The HNRNPK gene provides instructions for making a protein that regulates gene activity and protein production, playing a critical role in cellular growth, development, and neurological function.

Normal Function

The HNRNPK gene provides instructions for making a protein called heterogenous nuclear ribonucleoprotein K (hnRNP K). This protein attaches (binds) to DNA or its chemical cousin RNA and to other proteins. It acts as a docking site to bring together different molecules in the cell, which is important for relaying signals and controlling cellular functions.

By bringing certain proteins together with DNA or RNA, the hnRNP K protein helps control the activity of genes and the production of proteins. Through this regulation, it is involved in many cellular processes, including:

  • Growth and division (proliferation) of cells
  • Maturation of cells to take on specialized functions (differentiation)
  • Self-destruction (apoptosis) of cells when they are no longer needed

The hnRNP K protein also plays a role in the normal development or function of many body systems, particularly in the brain. It may be involved in synaptic plasticity—the ability of connections between neurons (synapses) to adapt over time, which is critical for learning and memory. It is also involved in the growth of nerve cell extensions called axons, which are essential for transmitting nerve impulses.

Health Conditions Related to Genetic Changes

Au-Kline syndrome

More than 20 mutations in the HNRNPK gene have been found to cause Au-Kline syndrome. This condition is characterized by weak muscle tone (hypotonia), intellectual disability, delayed development of speech and walking, and distinctive facial features. Other body systems, such as the heart, kidneys, and bones, may also be affected.

Mutations that cause this syndrome alter the blueprint for the hnRNP K protein, resulting in a shortage of the protein. This shortage disrupts normal gene activity and cell development, particularly in the brain, which likely contributes to the neurological features of the condition.

Cancers

Loss of the HNRNPK gene is thought to be involved in the development of a blood cancer known as acute myeloid leukemia (AML). In about 2 percent of AML cases, a mutation removes (deletes) DNA from the long (q) arm of chromosome 9, a region that includes the HNRNPK gene. Researchers suspect that a shortage of hnRNP K protein in these cases alters the activity of genes that control cell growth, leading to the uncontrolled cell growth that underlies AML.

Individuals with Au-Kline syndrome do not appear to have a higher risk of developing AML than the general population.

Frequently Asked Questions

Early signs often include weak muscle tone (hypotonia), which can make infants seem "floppy" and affect feeding or motor development. Developmental delays, particularly in reaching milestones like sitting, walking, and speaking, are also common. Distinctive facial features may be present from birth, and a healthcare provider might notice other systemic issues affecting the heart, kidneys, or bones during initial evaluations.
The hnRNP K protein is crucial for regulating gene activity and protein production, especially in the brain, where it supports synaptic plasticity (learning and memory) and axon growth (nerve impulse transmission). Mutations disrupt these vital processes, impairing normal brain development and function, which manifests as intellectual disability, delayed speech and walking, and other neurological issues.
Management is multidisciplinary and focuses on addressing specific symptoms. This often includes physical therapy for hypotonia and motor delays, occupational therapy for daily living skills, speech therapy for communication challenges, and educational support for intellectual disability. Regular medical monitoring for potential heart, kidney, or bone issues is also essential.
u-Kline syndrome is primarily caused by new (de novo) mutations in the HNRNPK gene, meaning the genetic change occurs spontaneously in the affected individual and is not inherited from either parent. In rare cases, a parent might have a very mild or mosaic form of the mutation, but most cases are sporadic. Genetic counseling can help families understand the recurrence risk.
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.