The CIT gene helps control the last step of cell division, when one cell splits into two, and this is especially important in the developing brain. This gene plays an important role in helping young brain cells multiply in an organized way. If the CIT gene does not work properly, brain growth can be reduced before birth, which can lead to primary microcephaly, developmental delay, and sometimes seizures. CIT is mainly known in rare disease genetics rather than in popular culture.
What is a gene?
Genes are stretches of DNA that hold instructions your cells use to make molecules or manage processes throughout the body. Some provide the directions for building proteins, which do much of the cell’s work. Others are mainly involved in regulating when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body grows and works, and they can influence your response to food, stress, and medications. More detail on this topic is available in the LearnHub.
Overview
CITGene function
What if the gene works
The CIT gene helps cells finish dividing. It is especially important in the developing brain, where it supports the final separation of new cells and steady brain growth.
Risk
What if the gene does not work
More disruptive variants in the CIT gene can impair brain cell division, causing primary microcephaly with a small head size, developmental delay, and intellectual disability. Milder variants may lead to later onset or less marked features.
Treatment
What does that mean for your treatment
For pathogenic variants in the CIT gene, no treatment or management approach specific to the CIT gene is currently established. Care is supportive and guided by the person's needs rather than by a gene directed drug choice. The CIT gene is being studied in early research as a possible biomarker or drug target in some cancers.
Conditions associated with CIT
Gene function
What if the gene works
At its core, the CIT gene function is to help cells complete the final stage of division. Its protein supports the pinching and separation steps that turn one cell into two organized new cells.
The CIT gene helps a dividing cell complete cytokinesis, the last step where one cell becomes two. Its protein gathers at the narrow bridge between the new cells and supports a clean separation.
Its protein helps organize actin and myosin, proteins that tighten like a drawstring during cell division. This gives the cell controlled force and shape as it pinches inward.
CIT also acts as a kinase (an enzyme that adds small chemical tags to proteins) during cell division. These signals help coordinate the timing and position of the final separation steps.
The CIT gene supports the midbody, a temporary structure that guides the last cut between two new cells. This helps each new cell keep clear boundaries as division wraps up.
What is a variant?
A gene variant is a small difference in the DNA sequence of a gene. These differences are common and help explain normal human diversity, including differences in appearance, metabolism, and the way the body reacts to environmental influences. Many variants do not cause any noticeable effect and are simply part of natural genetic variation. In some situations, though, a variant can change how a gene functions more significantly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Pathogenic variants in the CIT gene can change the protein’s shape, shorten it, or make it unstable, which may weaken its enzyme activity and disrupt cell division, especially in developing brain cells. In explaining how variants in the CIT gene affect protein function, milder missense variants may leave some activity, while more severe loss of function variants often lead to little or no working protein. This difference can influence when signs appear and how microcephaly and developmental difficulties become.
How variants are linked to conditions
Pathogenic variants in the CIT gene are linked to a rare inherited condition called primary microcephaly 17, which affects brain development. Babies are usually born with a much smaller head size, and many later have developmental delay, intellectual disability, seizures, or short stature. Among the conditions linked to CIT gene variants, this early onset neurodevelopmental condition is the best established and follows an autosomal recessive pattern, meaning both gene copies are affected.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are common across the general population. Most have no direct impact on health and simply reflect natural human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a certain 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?
There isn't broadly confirmed evidence on specific factors that increase or reduce health risk related to the CIT gene. For families with a known CIT gene change, personal risk depends mainly on the exact genetic finding and family history, and a doctor or genetic counselor can help explain what that means.
Inheritance of CIT variants
CIT gene variants linked to disease are inherited in an autosomal recessive pattern. This means a person usually inherits one altered copy of the CIT gene from each parent. Parents who each carry one CIT gene variant are often unaffected, but with each pregnancy there is a 25% chance of having a child with the condition, a 50% chance of having a child who is a carrier, and a 25% chance of having a child with two typical copies. In practical terms, CIT gene inheritance usually appears only when both parents pass on the same condition-related gene change.
What does my CIT result mean for my family?
For families with a disease-causing change in the CIT gene, the pattern is usually recessive, which means close relatives may also carry the same change without having symptoms. Brothers and sisters could be affected or be carriers, and other blood relatives may also carry it. Because of that, family members may want to discuss whether genetic testing is relevant for them, especially when planning a pregnancy.
Genetic information
Genetic testing
How you find out about variants
CIT gene genetic testing usually uses a blood or saliva sample to read your DNA and look for variants in the CIT gene. Labs often use sequencing (reading the DNA code), sometimes with checks for missing or extra pieces, and the result can clarify whether a CIT gene variant is present.
When should I consider getting a genetic test?
Consider testing for the CIT gene if a child has a much smaller head size than expected, major delays in development, seizures, or brain scan findings that suggest this rare inherited condition, especially when similar problems run in the family. Testing can help confirm whether a change in CIT is the cause.
A genetic result is only one part of your health story
A genetic finding can provide valuable insight, yet how much it explains varies based on the condition and the type of variant involved. Many factors, including lifestyle, environment, age, and medical history, shape how the body works over time. 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 can give a clear answer. In areas such as 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. A treatment that works well for one person may work less well for another, or may cause more side effects, because the body can absorb, break down, or respond to the drug differently. These differences are common and are one reason medication response is not the same for everyone. In some cases, a person’s genetic makeup can help explain why they are more sensitive to a medicine or why a standard treatment has a smaller effect.
What is Pharmacogenetics?
Pharmacogenetics examines the ways genetic variation shapes a person’s response to medicines. By studying links between genes and specific drugs, it helps explain why the same treatment can affect people differently. With many medications, genes influence both how the body handles the drug and how strong its effects may be. This information can support treatment decisions that are more informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the CIT gene
When should I seek medical advice?
There is no widely accepted evidence that changes in this gene should guide medicine choices, so any concerns about treatment, side effects, or new symptoms are best discussed with your doctor.