The FAM111B gene gives your cells instructions for a protein that helps support normal cell growth and tissue maintenance. This gene plays an important role in keeping changes in the skin, muscles, tendons, and lungs more controlled. When a harmful variant disrupts this job, it can cause an inherited condition marked by mottled skin changes, muscle weakness, tightening of tendons or joints, and sometimes lung scarring. Most people hear about the FAM111B gene through genetic testing for these symptoms rather than through public news or celebrity stories.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or regulate activities in the body. Some genes provide the information needed to produce proteins, which are the working parts of cells. Others mainly help direct when certain processes take place, where they happen, and how strongly they run. Together, genes affect how the body develops and works, and they can also shape how you respond to food, stress, or medications. To explore this topic in more detail, you can learn more in the LearnHub.
Overview
FAM111BGene function
What if the gene works
The FAM111B gene makes a protein that works mainly in the cell nucleus. It helps control protein breakdown and supports normal DNA copying and cell growth.
Risk
What if the gene does not work
Variants in the FAM111B gene can cause skin color changes, tight tendons, muscle weakness, and sometimes lung scarring. Effects can range from milder to more severe, which may influence when symptoms begin and which features appear.
Treatment
What does that mean for your treatment
No FAM111B-specific treatment or drug selection approach is currently established for people with pathogenic variants in the FAM111B gene. The FAM111B gene is being studied in early cancer research as a possible biomarker and drug target.
Conditions associated with FAM111B
Gene function
What if the gene works
FAM111B helps cells stay organized as they grow and copy their DNA. It makes a protein-cutting enzyme that is most active in the nucleus, where DNA is stored. Understanding how the FAM111B gene works helps explain how cells manage routine growth and division.
FAM111B makes an enzyme that trims selected proteins. This controlled cutting helps cells adjust protein activity during everyday cell work.
Inside the nucleus, the FAM111B protein supports the cell systems involved in copying DNA before a cell divides. This helps normal cell growth move forward in an orderly way.
Activity from this gene rises as cells prepare to divide. That timing helps coordinate protein control with routine cell cycle steps.
What is a variant?
A genetic variant is a minor change in the DNA sequence of a gene. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many variants have no noticeable effect and are simply part of natural genetic variation. In some cases, however, a variant changes how a gene functions more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the FAM111B gene often change the protein’s protein-cutting region, which can make its activity too strong or less tightly controlled. This helps explain how FAM111B gene variants affect protein function at the cell level. Some changes seem to disturb other proteins and interfere with how cells copy DNA before they divide. Variants with larger functional effects are often linked with earlier onset or a broader range of features.
How variants are linked to conditions
Pathogenic variants in the FAM111B gene cause a rare inherited condition called hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis, often shortened to POIKTMP. This FAM111B gene condition can affect the skin, muscles, joints, and lungs. Some people also have poor growth, liver changes, or pancreas problems.
A variant is not necessarily a diagnosis
Variants in genes are a normal feature of human biology and are widely found across the general population. Most do not directly affect health and instead reflect the natural range of human variation. For many genes, having a variant associated with a condition points to a possible link rather than a clear diagnosis, particularly when several genes and environmental influences play a role. In other situations, though, one well-understood variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the FAM111B gene. In families with a disease-causing FAM111B change, the main factor is usually whether that genetic change is present, rather than lifestyle or environmental exposures. Anyone worried about their personal or family risk should speak with a doctor or genetic counselor.
Inheritance of FAM111B variants
FAM111B-related conditions are inherited in an autosomal dominant pattern, which means a person usually needs one altered copy of the FAM111B gene to have the condition. If a parent carries a disease-causing variant in the FAM111B gene, each child has a 50% chance of inheriting it. This is the main answer to how FAM111B gene variants are inherited in families. Some people with a FAM111B variant are the first in their family to have it because the variant arose new (de novo) and was not inherited from either parent.
What does my FAM111B result mean for my family?
For FAM111B, family implications usually follow a dominant pattern, so close relatives such as a parent, brother, sister, or child may also carry the same gene change. Each child of someone with a disease-causing FAM111B variant has a 50% chance of inheriting it. Some FAM111B changes happen for the first time in one person, so a parent is not always the source.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a change in the FAM111B gene, doctors use FAM111B genetic testing on a blood sample or saliva sample. The lab reads the gene's DNA code to look for variants and may report whether a finding helps confirm a genetic diagnosis or is unlikely to explain symptoms.
When should I consider getting a genetic test?
Genetic testing for the FAM111B gene may be worth considering if you or a close relative has a mix of early skin changes, tightening of the fingers or other joints, muscle weakness, or lung scarring that seems to run in the family. A disease-causing change in FAM111B can confirm an inherited condition and help guide follow-up for the lungs, muscles, and skin.
A genetic result is only one part of your health story
A genetic finding can be informative, but how much it explains varies depending on the condition and the specific type of variant. Many factors, including lifestyle, environment, age, and medical history, influence how the body functions over time. For some conditions, especially those shaped by many genes, genetic information provides context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result may offer a clear answer. In areas like medication response, genetic results can also help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. This helps explain why the same medication may work well for one person but less well for another, or why some people are more sensitive to side effects. Small differences in the genes involved in how the body absorbs, breaks down, or responds to a drug are common, and they can influence how strongly a treatment works.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences affect a person’s response to medications. By looking at connections between genes and drugs, it helps explain why the same treatment may work differently from one person to another. For many medicines, genes influence both how strongly a drug works and how the body processes it. This understanding can support treatment decisions that are more informed and more individualized. If you want to explore this topic further, you can learn more in the LearnHub.
Drugs influenced by the FAM111B gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choice or dose. Questions about medicines, side effects, or changes in your health are best discussed with your doctor or pharmacist.
History
The FAM111B gene entered the medical literature relatively recently, after clinicians recognized a rare inherited pattern of skin changes, muscle weakness, and scarring in the lungs across several families. In 2013, researchers linked this pattern to variants in the FAM111B gene, helping define a condition now called poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis. Initially understood only through visible traits, later recognized as tied to a specific gene, this finding gave families a clearer explanation for symptoms that had previously been hard to group together. From these first observations, research expanded steadily. Over time, descriptions became more precise as additional families were reported and the range of features associated with FAM111B became clearer.