The STS gene makes an enzyme that helps break down sulfate-tagged steroid molecules, which supports normal skin shedding and hormone balance. This gene plays an important role in keeping the outer skin layer from building up too much. If the gene does not work, people may develop X-linked ichthyosis, which causes dry, dark, scaly skin, and in pregnancy it can reduce placental estrogen production and contribute to labor that starts later or progresses more slowly.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or guide processes throughout the body. Some genes provide the directions for producing proteins, which are the working parts of cells. Other genes mainly regulate when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body develops and works, and they can also influence how you respond to food, stress, or medications. More detailed information on this topic is available in the LearnHub.
Overview
STSGene function
What if the gene works
The STS gene helps cells convert certain sulfated steroids into active forms. This supports normal skin shedding and helps make hormones available in the skin, placenta, and other tissues.
Risk
What if the gene does not work
Reduced activity of the STS gene often causes X linked ichthyosis, with dry, scaly skin from birth or early childhood. Milder or larger, more disruptive variants can affect severity and may add undescended testes or attention differences.
Treatment
What does that mean for your treatment
For a pathogenic variant in the STS gene, no STS-specific treatment or drug choice is currently established in clinical guidelines. Care is usually guided by symptoms rather than the STS gene itself, and STS is also being studied as a possible drug target in some hormone-sensitive cancers.
Conditions associated with STS
Gene function
What if the gene works
This gene makes the steroid sulfatase enzyme, which helps your body turn stored steroid sulfates into forms that cells can use more easily. Your cells rely on the STS gene to keep some hormone signals available when needed. It also supports normal skin renewal.
The STS gene removes sulfate tags from steroid sulfates, a step that frees hormone precursors for use. This helps tissues draw on a steady supply of estrogen and androgen building blocks.
By converting stored forms of estrogen and androgen precursors, this gene helps control how much steroid signaling is available in each tissue. That allows cells to fine tune hormone activity for everyday needs.
In the outer skin layer, the STS gene helps process cholesterol sulfate, a molecule involved in how skin cells mature and separate. This supports normal shedding of older skin cells and helps maintain the skin barrier.
What is a variant?
A genetic variant is a minor change in a gene’s DNA sequence. These changes are common and help explain normal differences among people, such as appearance, metabolism, or the way the body responds to environmental influences. Many variants do not cause any 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
In X-linked ichthyosis, variants in the STS gene often reduce or eliminate steroid sulfatase, causing cholesterol sulfate to build up in skin cells and making normal shedding less efficient. Milder variants may leave some enzyme activity, while larger deletions or other more disruptive variants usually cause a stronger loss of function. This range can influence how early scaling appears and how noticeable it is.
How variants are linked to conditions
Pathogenic variants or deletions in the STS gene cause X-linked ichthyosis, so the STS gene and X-linked ichthyosis are closely linked in clinical genetics. This condition mainly affects the skin and often leads to dry, dark, tightly adherent scales. Some people also have corneal clouding or undescended testes. Larger deletions that include the STS gene and nearby genes can be linked to a broader set of findings, such as short stature or learning difficulties.
A variant is not necessarily a diagnosis
Variants are a normal feature of human biology and are common throughout the general population. Most have no direct impact on health and are simply part of natural human diversity. For many genes, carrying a variant associated with a condition points to a possible link rather than a definite diagnosis, especially when more than one gene and environmental factors are involved. In some situations, though, a single well-characterized variant in a specific gene can be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For STS, risk is driven mainly by the genetic change you inherit, so lifestyle factors are not known to meaningfully lower the chance of the related skin condition. Family history changes the chance of inheriting it, and sex matters too, because males are much more likely to have symptoms while many female carriers have few or no symptoms.
Inheritance of STS variants
Variants in the STS gene are inherited in an X linked pattern, most often X linked recessive, as seen in X linked ichthyosis. For families asking how STS gene variants are inherited, a mother who carries the variant can pass it to sons, who may be affected, and to daughters, who may be carriers. A father with an STS gene variant passes his X chromosome to all daughters and none of his sons, so sons do not inherit it from him. Because the STS gene is on the X chromosome, inheritance differs between males and females.
What does my STS result mean for my family?
A change in the STS gene can run through families in an X-linked pattern. This often means brothers, maternal uncles, or other male relatives on the mother’s side could also have the condition, while some female relatives may carry the gene change without clear symptoms. Family testing can help clarify who else may be affected or who may be a carrier.
Genetic information
Genetic testing
How you find out about variants
To look for changes in the STS gene, labs usually use STS genetic testing on a blood or saliva sample, with sequencing plus deletion and duplication analysis. This can detect common whole-gene deletions and smaller variants. Results may confirm a diagnosis or show whether someone carries an STS variant.
When should I consider getting a genetic test?
If there is a family history of X-linked ichthyosis, or a child, especially a boy, has ongoing dark, dry, scaly skin from infancy, testing the STS gene may help confirm the cause. It can also help clarify the chance of passing this condition on in future pregnancies.
A genetic result is only one part of your health story
Genetic findings can provide meaningful insight, but how much they explain varies based on the condition and the specific variant involved. Over time, factors such as lifestyle, environment, age, and medical history also shape how the body functions. For some conditions, especially those influenced by many genes, genetic information offers context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic results can 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 treatment works well for one person, has less effect in another, or causes more side effects in someone else. Differences in how the body breaks down, moves, or responds to a drug are common, and they can influence both benefit and sensitivity to treatment.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes can affect the way they respond to medicines. By studying links between genes and medications, it helps explain why the same treatment may work differently in different people. For many drugs, genes can influence how much effect a medicine has or how the body handles it. This information can support treatment decisions that are better informed and more individualized. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the STS gene
When should I seek medical advice?
There isn't yet a broadly confirmed role for this gene in predicting how most medicines will work. For questions about side effects, a new medicine, or changes in how you feel on treatment, speak with your doctor or pharmacist.