The STAR gene helps the adrenal glands and gonads turn cholesterol into steroid hormones, including cortisol, aldosterone, and sex hormones. This gene plays an important role in moving cholesterol to the place inside cells where hormone production starts. If both copies have harmful variants, the body may make too little of these hormones, which can lead to congenital lipoid adrenal hyperplasia. Babies may develop vomiting, dehydration, low blood pressure, poor weight gain, and differences in sex development.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or regulate activities in the body. Some genes provide the directions for producing proteins, the parts of cells that do the work. Others mainly control when certain processes happen, where they take place, and how strong they are. As a group, genes influence how the body develops and functions, and they can shape how you respond to food, stress, or medications. For a deeper look at this topic, you can find more in the LearnHub.
Overview
STARGene function
What if the gene works
The STAR gene helps move cholesterol inside certain cells so they can make steroid hormones. These hormones include cortisol, aldosterone, and sex hormones, which support stress response, salt balance, and sexual development.
Risk
What if the gene does not work
Variants in the STAR gene can reduce or block hormone production. More severe variants often cause congenital lipoid adrenal hyperplasia with adrenal insufficiency, salt loss, and sex development differences, while milder variants may appear later with less severe hormone problems.
Treatment
What does that mean for your treatment
A pathogenic or loss-of-function variant in the STAR gene usually means treatment centers on lifelong steroid hormone replacement rather than a targeted gene-specific drug. This often includes glucocorticoids, often mineralocorticoids and salt in infancy, with extra stress-dose steroids during illness, injury, or surgery. Some people also need sex hormone replacement later, depending on age, sex development, and remaining hormone production.
Conditions associated with STAR
Gene function
What if the gene works
Some cells rely on the STAR gene to turn cholesterol into key hormones your body uses every day. In the adrenal glands and gonads, its protein moves cholesterol to the right place inside the cell. This is an early step in how your body makes steroid hormones.
The STAR gene helps steroid making cells move cholesterol into mitochondria (small structures inside cells). This places the raw material where hormone production can begin.
By guiding cholesterol to the right spot, this gene starts one of the first steps in steroid hormone production. That process helps your body make hormones such as cortisol, aldosterone, estrogen, progesterone, and testosterone.
STAR activity lets the adrenal glands and gonads increase hormone making when the body sends a signal. This helps daily needs like stress response, salt balance, puberty, and reproduction be met in a controlled way.
What is a variant?
A genetic variant is a minor change in the DNA sequence of a gene. These changes are common and help create 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, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the STAR gene can reduce or block cholesterol transfer into mitochondria, the cell compartments where steroid hormones begin to be made. The functional effect of STAR gene variants on steroid production often depends on how much protein activity remains. Milder variants may leave partial activity, while more severe variants can disrupt protein folding, stability, or mitochondrial targeting and nearly abolish activity. That difference can influence whether symptoms appear later or begin in infancy.
How variants are linked to conditions
Pathogenic variants in the STAR gene cause congenital lipoid adrenal hyperplasia, a rare inherited form of adrenal insufficiency. This STAR gene condition may begin in infancy or, in milder nonclassic forms, later in childhood or adulthood. Some people, especially those with 46,XY chromosomes, also have differences in sex development linked to STAR-related disease.
A variant is not necessarily a diagnosis
Genetic variants are common across the general population and are a normal feature of human biology. Most do not directly affect health and simply contribute to natural human variation. For many genes, having a variant associated with a condition points to a possible link rather than a confirmed diagnosis, particularly when several genes and environmental influences play a role. In some 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?
For STAR, risk is mostly determined by inheritance: a child is at higher risk only if they inherit harmful changes in both copies of the STAR gene, usually from two carrier parents. This chance can be higher when parents are related by blood. Lifestyle factors are not known to meaningfully change the chance of this condition.
Inheritance of STAR variants
STAR-related conditions are inherited in an autosomal recessive pattern. This means a child usually needs to inherit one STAR gene variant from each parent to be affected, while parents with one variant are typically carriers. When both parents carry a variant in the STAR gene, each pregnancy has a 25% chance of an affected child, a 50% chance of a carrier child, and a 25% chance of a child with neither variant. This is the key point behind how STAR gene variants are inherited in families.
What does my STAR result mean for my family?
Changes in the STAR gene usually matter for family members in a recessive way, which means parents are often healthy carriers. Brothers and sisters may also be affected or may be carriers, so the result can be relevant beyond one person in the family. Other close relatives, such as future children of siblings, may also want to know there is a carrier pattern in the family.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for STAR gene variants usually uses a blood or saliva sample to read the STAR gene and look for changes in its DNA code. This kind of STAR gene genetic testing can confirm whether a person carries a disease-causing variant, show if they are a carrier, or sometimes find a variant of uncertain significance, which needs clinical interpretation.
When should I consider getting a genetic test?
Consider STAR testing if a baby or child has unexplained adrenal gland failure, repeated low-salt dehydration, or problems making stress hormones. It can also help when there is a family history of this condition or a baby is born with differences in sex development.
A genetic result is only one part of your health story
A genetic finding can provide valuable insight, but how much it explains depends on the condition and the type of variant involved. Many factors, including lifestyle, environment, age, and medical history, influence how the body works over time. In some conditions, especially those shaped by many genes, genetic information provides context rather than certainty and is most useful when viewed alongside other parts of care. In other situations, a genetic result can offer a clear answer. In areas such as medication response, genetic results may help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small inherited differences can change how the body breaks down a drug, moves it through the bloodstream, or responds at the target the drug is meant to act on. This helps explain why the same medication may work well for one person, do little for another, or cause more side effects in someone who is more sensitive to it.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences affect the way people respond to medications. It focuses on connections between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes can influence how strongly a drug works or how the body handles it. This information can support more informed, more individualized treatment decisions. You can read more about this topic in the LearnHub.
Drugs influenced by the STAR gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting how medicines will work. If you have concerns about side effects, hormone treatment, or changes to any of your medicines, talk with your doctor or pharmacist.
History
The STAR gene came into view in the 1990s as researchers worked to explain a rare inherited form of adrenal failure that affected babies soon after birth. In 1995, scientists identified harmful variants in the STAR gene as the cause of congenital lipoid adrenal hyperplasia, a landmark finding for hormone genetics. Initially understood only through visible traits, later recognized as tied to a specific gene, this condition helped connect long-standing clinical observations with a clear genetic cause. Building on this early work, scientists uncovered more about the STAR gene in steroid producing tissues such as the adrenal glands and ovaries or testes. That discovery helped shape modern understanding of inherited problems with steroid hormone production and remains an important part of endocrine genetics today.