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SMAD4 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SMAD4 gene

The SMAD4 gene provides instructions for a protein that acts as a tumor suppressor and a key component of the TGF-β signaling pathway, which regulates cell growth and development.

Normal Function

The SMAD4 gene provides instructions for making a protein involved in transmitting chemical signals from the cell surface to the nucleus. It is a key part of the transforming growth factor beta (TGF-β) signaling pathway. When a TGF-β protein binds to a cell surface receptor, it activates a group of SMAD proteins that bind to the SMAD4 protein. This complex then moves to the nucleus to control gene activity and regulate cell growth and division.

The SMAD4 protein functions as both a transcription factor, which controls gene activity, and a tumor suppressor, which prevents cells from growing or dividing too rapidly.

Health Conditions Related to Genetic Changes

Hereditary hemorrhagic telangiectasia

Mutations in the SMAD4 gene can cause a form of this disorder known as juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome. This condition involves:

  • Arteriovenous malformations: Abnormal connections between arteries and veins.
  • Telangiectases: Visible red markings on the skin caused by surface vessel abnormalities.
  • Increased risk of intestinal polyps that may become cancerous.

Juvenile polyposis syndrome

At least 78 mutations in the SMAD4 gene are associated with juvenile polyposis syndrome, characterized by multiple noncancerous (benign) growths called juvenile polyps. These mutations often result in a nonfunctional protein, preventing the SMAD complex from reaching the nucleus to regulate cell proliferation, leading to unregulated cell growth.

Myhre syndrome

At least four "gain-of-function" mutations in the SMAD4 gene cause Myhre syndrome. These mutations result in an abnormally stable protein that remains active longer than necessary. This leads to excessive TGF-β signaling, causing symptoms such as:

  • Intellectual disability
  • Fibrosis (buildup of scar tissue) in skin and internal organs
  • Problems affecting multiple body systems

Cancers and Other Disorders

Mutations in SMAD4 are linked to an increased risk of various cancers, particularly in the colon and pancreas. Additionally, some individuals with SMAD4 mutations may experience cardiovascular issues, including aortic dilation (weakening and stretching of the aorta), aneurysms, or mitral valve dysfunction.

Other Names for This Gene

  • DPC4
  • JIP
  • MAD (mothers against decapentaplegic, Drosophila) homolog 4
  • MADH4
  • SMAD, mothers against DPP homolog 4 (Drosophila)
  • SMAD4_HUMAN

Frequently Asked Questions

Red, blanching spots (telangiectases) on the lips, tongue, or fingertips are common early clues. New or worsening nosebleeds, shortness of breath, or unexplained fatigue can signal pulmonary AVMs. Gastrointestinal bleeding, iron‑deficiency anemia, or a sudden drop in oxygen saturation should prompt imaging (CT or MRI) to evaluate for visceral AVMs.
Testing is done with a blood or saliva sample analyzed by a clinical genetics laboratory. A targeted SMAD4 gene panel or whole‑exome sequencing can detect pathogenic variants. Because juvenile polyposis is inherited in an autosomal‑dominant pattern, a single abnormal copy is enough to raise risk, so testing is recommended if you have a family history of polyps, early‑onset colorectal cancer, or related skin/vascular findings.
Guidelines suggest colonoscopy (or flexible sigmoidoscopy) beginning at age 12‑15, or earlier if symptoms appear, and then repeated every 1‑2 years depending on polyp burden. Upper endoscopy is also advised every 2‑3 years to monitor for gastric or duodenal polyps, because SMAD4 mutations increase the risk of polyps throughout the GI tract.
Research is ongoing, but some clinicians use angiotensin‑II receptor blockers (e.g., losartan) off‑label because they can dampen TGF‑β activity and have shown modest benefit in related connective‑tissue disorders. Enrollment in clinical trials targeting TGF‑β pathway inhibitors is another option; discuss with a medical geneticist or a specialist familiar with Myhre syndrome.
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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