The SYCE1 gene helps the body make eggs and sperm by supporting the careful pairing of chromosomes during meiosis, the special cell division used for reproduction. If it does not work, eggs or sperm may not form properly, which can lead to infertility. Some people with pathogenic variants in both copies of the SYCE1 gene may be diagnosed with primary ovarian insufficiency or with very low or absent sperm production. SYCE1 is mainly known in fertility medicine rather than popular culture.
What is a gene?
Genes are stretches of DNA that hold information your cells use to make molecules or regulate processes in the body. Some genes provide the instructions for making proteins, the parts of cells that do the work. Others mainly help determine when certain processes happen, where they occur, and how strongly they operate. Taken together, genes affect how the body develops and works, and they can influence how you respond to food, stress, or medications. More on this topic is available in the LearnHub.
Overview
SYCE1Gene function
What if the gene works
The SYCE1 gene helps reproductive cells line up matching chromosomes during meiosis, the special cell division that makes eggs and sperm. This supports normal chromosome exchange and separation.
Risk
What if the gene does not work
Variants in the SYCE1 gene can disrupt egg or sperm formation and often lead to infertility. In men, this is usually little or no sperm production; in women, it can cause primary ovarian insufficiency. Effects may vary with variant severity.
Treatment
What does that mean for your treatment
Pathogenic variants in the SYCE1 gene do not currently change medication choices, and no SYCE1-specific treatment or management approach is established.
Conditions associated with SYCE1
Gene function
What if the gene works
Your body uses the SYCE1 gene during the special cell division that makes eggs and sperm. Its protein becomes part of a temporary structure that helps matching chromosome pairs line up closely. This careful setup supports normal exchange of genetic material before reproductive cells are formed.
The SYCE1 gene helps matching chromosome pairs align closely during the cell division that makes eggs and sperm. This close pairing lets each pair stay organized while the cell prepares to separate them.
Its protein forms part of a bridge between chromosome pairs. This temporary support keeps the paired chromosomes connected in an orderly way during an important stage of reproductive cell formation.
When chromosome pairs are held together properly, they can swap small sections of DNA. This normal mixing step helps create healthy genetic variety in sperm and egg cells.
What is a variant?
A genetic variant is a small difference in the DNA sequence of a gene. These differences are common and help shape normal human diversity, including variation in appearance, metabolism, and how the body responds to environmental influences. Many have no noticeable effect and are simply part of natural genetic variation. In some cases, however, a variant can change 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 SYCE1 gene can alter the SYCE1 protein's shape or stability, reduce how much is made, or create a shortened protein that cannot join the chromosome pairing structure cells use during egg and sperm formation. In terms of how SYCE1 gene variants affect function, milder changes may leave activity, while more severe biallelic variants that stop the gene from working can block meiosis (the cell division that makes eggs and sperm) and are linked to complete infertility.
How variants are linked to conditions
Pathogenic variants in the SYCE1 gene are linked to inherited infertility. In females, variants in both copies of the SYCE1 gene can cause primary ovarian insufficiency, which may lead to absent or irregular periods and trouble getting pregnant. In males, SYCE1 gene variants linked to infertility have been associated with nonobstructive azoospermia and severe sperm production problems. These findings mainly involve rare variants inherited from both parents.
A variant is not necessarily a diagnosis
Variants in genes are a usual part of human biology and are widespread in the general population. Most do not directly affect health and instead reflect normal human variation. For many genes, having a variant associated with a condition suggests a possible link rather than a confirmed diagnosis, particularly when several genes and environmental factors play a role. In some situations, though, a single well-characterized variant in a specific 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 risk related to the SYCE1 gene. For many living with a SYCE1 gene change, risk depends most on the exact variant and whether one or both copies of the gene are affected.
Inheritance of SYCE1 variants
The inheritance of the SYCE1 gene variants linked to known SYCE1 related fertility conditions is autosomal recessive. This means a person usually inherits one SYCE1 gene variant from each parent, and both copies need to carry a disease causing change for the condition to be present. Parents who each carry one variant are typically unaffected carriers, and with each pregnancy they have a 25% chance of having a child with the condition, a 50% chance of having a child who is also a carrier, and a 25% chance of having a child with no inherited variant in that gene.
What does my SYCE1 result mean for my family?
For SYCE1, family implications are usually most relevant in brothers and sisters, because this gene is linked to inherited fertility conditions that often run in families in a recessive pattern. That means siblings may also have the condition or be carriers, even if parents have never had symptoms. Parents are often healthy carriers, and children of someone with a SYCE1-related condition will usually be carriers unless the other parent also carries a SYCE1 change.
Genetic information
Genetic testing
How you find out about variants
To look for changes linked to infertility, SYCE1 genetic testing usually examines DNA from a blood or saliva sample. A lab reads the SYCE1 gene and checks for variants by comparing your sequence with the usual reference sequence. Results may show no relevant variant, a benign variant, or a variant that can help explain reduced fertility.
When should I consider getting a genetic test?
Testing for the SYCE1 gene may be worth considering as part of an infertility workup, especially for men with no sperm in the semen because sperm development stops early, or for women whose ovaries stop working much earlier than expected. It can also be relevant when similar fertility problems run in the family.
A genetic result is only one part of your health story
A genetic result can be informative, but how much it explains varies by the condition and the specific type of variant. Over time, many other factors also influence how the body works, including lifestyle, environment, age, and medical history. For some conditions, especially those shaped by many genes, genetic information provides context rather than certainty and is most useful when viewed together with other parts of care. In other situations, a genetic result can give a clear answer. In areas such as medication response, genetic results may also help put a person’s experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in genes can change how the body breaks down a drug, moves it through the body, or responds to it at its target. This is one reason the same medication may work well for one person, seem less effective for another, or cause more side effects in someone else.
What is Pharmacogenetics?
Pharmacogenetics examines the ways genetic differences affect how people respond to medicines. By studying links between genes and drugs, it helps explain why the same treatment can work differently in different people. With many medications, genes can influence both how much effect a drug has and how the body handles it. This information can support treatment decisions that are more informed and more tailored to the individual. More on this topic is available in the LearnHub.
Drugs influenced by the SYCE1 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting medication response, so any concerns about your health, fertility, or possible medicine side effects are best discussed with your doctor.
History
Research on the SYCE1 gene grew out of efforts to understand how eggs and sperm form correctly during meiosis, the special cell division used to make reproductive cells. In recent decades, awareness of this gene’s role has grown as scientists mapped the proteins that build the synaptonemal complex, a structure that helps chromosomes pair up. SYCE1 was identified as one of the central parts of that structure in the 2000s, which gave researchers a clearer picture of why meiosis can fail. From these first observations, research expanded steadily, linking changes in the SYCE1 gene with some cases of infertility in both women and men. This work helped move the field from microscope based descriptions to a more precise genetic understanding.