The ASPM gene helps guide how brain cells divide during early development, which supports normal brain growth before birth. This gene plays an important role in building the developing cerebral cortex, the part of the brain involved in thinking, language, and movement. If you carry harmful variants in both copies of the ASPM gene, this can cause primary microcephaly, with a smaller head size and brain from birth. Many affected people also have developmental delay or intellectual disability, though the severity can vary.
What is a gene?
Genes are stretches of DNA that hold instructions your cells use to make molecules or guide processes in the body. Some genes carry the information needed to produce proteins, which do much of the work inside cells. Other genes mainly regulate when certain processes happen, where they take place, and how strongly they run. Taken as a whole, genes influence how the body develops and functions, and they can shape how you respond to food, stress, or medications. To go into this topic in more detail, you can find more in the LearnHub.
Overview
ASPMGene function
What if the gene works
The ASPM gene helps cells divide in an organized way. It is especially important during early brain development, where it supports the growth of the cerebral cortex.
Risk
What if the gene does not work
When the ASPM gene does not work properly, brain growth before birth is reduced, often causing primary microcephaly and developmental delay or intellectual disability. Milder to more severe variants can influence how early features appear and how marked they are.
Treatment
What does that mean for your treatment
No treatment or drug choice specific to pathogenic variants in the ASPM gene is currently established in clinical guidelines. Care is guided by a person's symptoms and developmental needs rather than by the variant itself.
Conditions associated with ASPM
Gene function
What if the gene works
When cells divide, timing and structure have to line up with care. The ASPM gene helps guide this process, especially in early brain development and other fast growing tissues. Its protein works at the poles of the mitotic spindle, the framework that pulls chromosomes apart, supporting orderly division from one generation of cells to the next.
ASPM helps organize the mitotic spindle, the framework that separates chromosomes during cell division. It gathers at the spindle poles so the pull on chromosomes stays balanced.
During division, the ASPM gene supports accurate chromosome movement into the two new cells. This helps each daughter cell receive a full set of genetic material.
The ASPM gene helps control the angle and symmetry of cell division. In developing tissues, this supports a healthy balance between making more precursor cells and making specialized cells.
In the developing brain, ASPM is active in neural precursor cells that divide many times. This is central to the ASPM gene’s role in brain development, helping maintain the cell supply needed to build the cerebral cortex.
What is a variant?
A genetic variant is a minor change in the DNA sequence within a gene. These changes are common and help shape normal human diversity, including differences in appearance, metabolism, or how the body reacts to environmental influences. Many variants do not cause any noticeable effect and simply represent natural genetic variation. In some cases, though, a variant can more clearly change how a gene works and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the ASPM gene often reduce how much working ASPM protein a cell can make. Many more severe variants create a shortened, unstable protein or stop production altogether, which disrupts how chromosomes are shared during cell division in developing brain cells and shows how ASPM gene variants affect brain growth. Milder variants may leave some protein activity, and in some families this is linked to later onset or less marked features than when both gene copies lose function.
How variants are linked to conditions
Pathogenic variants in the ASPM gene are a well-established cause of primary microcephaly, often called primary microcephaly 5. In ASPM gene and primary microcephaly, the main feature is a head size much smaller than expected from birth or early infancy, and some children also have developmental or learning difficulties. The condition usually occurs when a child inherits one disease-causing variant from each parent.
A variant is not necessarily a diagnosis
Across the general population, genetic variants are common and are a normal feature of human biology. Most do not have a direct effect on health and instead reflect natural human diversity. For many genes, carrying a variant linked to a condition indicates a possible association rather than a definite diagnosis, especially when several genes and environmental factors are involved. 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?
For ASPM, risk is mostly shaped by inheritance rather than lifestyle. The chance is higher when both parents carry a changed ASPM gene, and it can also be higher in families where blood relatives have children together. Once a child inherits changed copies from both parents, day-to-day habits are not known to meaningfully change whether the condition develops.
Inheritance of ASPM variants
ASPM-related primary microcephaly is inherited in an autosomal recessive pattern. This means a child usually inherits one altered copy of the ASPM gene from each parent. Parents who each carry one ASPM gene variant are usually unaffected carriers, and with each pregnancy there is a 25% chance the child will have the condition, a 50% chance the child will be a carrier, and a 25% chance the child will inherit neither variant. This ASPM gene inheritance pattern affects sons and daughters equally.
What does my ASPM result mean for my family?
For ASPM, family implications are usually those of a recessive condition affecting brain growth, including primary microcephaly. Brothers and sisters may also be affected or may be healthy carriers, and close relatives on both sides of the family may carry the same gene change without knowing it. Family members may want to learn whether the same result runs in the family, especially if there is a history of babies born with a much smaller head size than expected.
Genetic information
Genetic testing
How you find out about variants
Variants in the ASPM gene are found with genetic testing, usually by analyzing a blood sample or saliva sample to read the gene’s DNA code. ASPM genetic testing can confirm whether a person carries a variant, help clarify the cause of a related condition, and may also show whether close relatives carry the same change.
When should I consider getting a genetic test?
Genetic testing for the ASPM gene may be worth considering if a baby or child has a much smaller-than-expected head size from before birth or at birth, especially with developmental delays. It can also help when this pattern runs in the family or when pregnancy scans have raised concern.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, but what it can tell you varies with the condition and the kind of variant present. Over time, factors like lifestyle, environment, age, and medical history also shape how the body functions. For some conditions, particularly those shaped by many genes, genetic information offers context rather than certainty and makes the most sense alongside the rest of a person’s care. In other situations, it may give a clear answer. In areas like medication response, genetic results can also help frame individual experiences.
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, and move drugs differently based on inherited DNA changes. This kind of variation is common and can influence both how strongly a medicine works and how sensitive someone is to it.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape a person’s response to medications. By looking at links between genes and drugs, it helps explain why the same treatment may work differently from one person to another. For many medicines, genes affect both how strongly a drug works and how the body handles it. This information can support more informed, individualized treatment decisions. More detail on this topic is available in the LearnHub.
Drugs influenced by the ASPM gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in how medicines work, so any concerns about symptoms, side effects, or whether a treatment is right for you are best discussed with your doctor.
History
Researchers identified the ASPM gene in the early 2000s while studying families with primary microcephaly, a condition in which the brain and head are smaller than expected from early development. Its discovery helped explain a long-standing medical question about why this pattern can run in families. From these first observations, research expanded steadily. Soon after, the ASPM gene also drew attention in human evolution research because scientists explored whether changes in it might be linked to differences in brain size over time. That idea gained wide public interest, although later work showed the story is more complex than early headlines suggested. Today, ASPM is best known for its role in inherited microcephaly and for the debate it sparked about how genes are interpreted in evolution.