Christianson Syndrome: The Rare Genetic Condition That Affects Walking, Speaking, and Why It Mostly Affects Boys
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 14, 2026
Quick Answer
Christianson syndrome is a rare genetic disorder, mostly affecting males, that causes severe nervous system problems such as trouble walking and speaking, intellectual disability and balance issues. [1] [2] It is caused by a mutation in the SLC9A6 gene on the X chromosome and diagnosed with a blood test. [1] There is no cure, but supportive care can improve quality of life. [1]
What the research says
The type of gene change shapes how severe it is. In 5 boys with SLC9A6 variants, the 3 with null (loss-of-function) variants had hard-to-control epilepsy and severe developmental delay, while 1 boy with a milder missense variant became seizure-free. (Jiao et al., Orphanet Journal of Rare Diseases, 2025) [5].
The faulty gene leaves cells without the NHE6 protein. Lab tests on cells from 2 children with typical Christianson syndrome found sharply lower gene activity and no detectable normal NHE6 protein, along with damaged mitochondria and fat droplets. (He et al., CNS Neuroscience & Therapeutics, 2023) [6].
What Is Christianson Syndrome?
Christianson syndrome is a rare genetic disorder. It causes severe problems with your nervous system. [1] [4] It occurs when one or both biological parents pass down a specific gene change (mutation). This condition mostly affects males and leads to intellectual disability, balance issues or loss of speaking skills. [1] [2] These symptoms may improve for a period, then worsen over time. [1]
Key terms at a glance: A genetic disorder happens because of a change, or mutation, in a gene. An X-linked genetic disorder is caused by a mutation on the X chromosome — one of the chromosomes that determines biological sex. Microcephaly is an unusually small head. Ataxia is a problem with balance and movement. Hypotonia is low muscle tone.
Term | What It Means |
|---|---|
SLC9A6 gene | The gene in the X chromosome where the mutation that causes Christianson syndrome occurs |
X-linked genetic disorder | A condition caused by a mutation on the X chromosome |
Carrier | Someone who has the gene change but doesn't have symptoms of the condition |
Ataxia | Problems with balance and movement |
Microcephaly | An unusually small head |
Hypotonia | Low muscle tone |
Regression | When speaking or walking skills improve for a period and then worsen |
Cerebellar atrophy | When the part of the brain that controls posture and balance stops growing or gets smaller |
People with this condition have trouble walking and speaking. They typically also have developmental delays or intellectual disabilities. [1] [4] People with Christianson syndrome often start showing symptoms of the condition when they're infants. [1] [2] [4]
Who Does Christianson Syndrome Affect?
Christianson syndrome mostly affects males. [1] [2] The condition is an "X-linked genetic disorder." This means it occurs because of a change (mutation) in X chromosomes.
Females have two X chromosomes, while males have one X chromosome and one Y chromosome. If a female has the mutation that causes Christianson syndrome on one X chromosome, they still have one functioning X chromosome. Because of this, they aren't likely to develop Christianson syndrome. [1] [4]
If a male has the gene mutation, they have no other X chromosome to take over typical functions. They'll develop Christianson syndrome. For a female to develop Christianson syndrome, they'd have to have gene mutations on both X chromosomes, which is extremely rare. [1]
How Common Is Christianson Syndrome?
Experts don't know exactly how many people have Christianson syndrome. They do know it's extremely rare. [1] By some estimates, about 1 in 600 boys have an X-linked intellectual disability. [1] One study found Christianson syndrome in about 1 in 100 families who had a child with an X-linked developmental disability. [1] [2]
What Are the Symptoms?
Most people with Christianson syndrome who are male have balance and movement issues (ataxia); epilepsy; eye problems such as strabismus (crossed eyes); inability to speak; intellectual disability; and an unusually small head (microcephaly). [1] [2]
Some people also have autism spectrum disorder; cerebellar atrophy, when the part of their brain that controls posture and balance stops growing or gets smaller; gastrointestinal symptoms, such as gastroesophageal reflux disease (GERD); loss of walking skills; low muscle tone (hypotonia); and low weight or short stature. [1]
Common Symptoms (Most Males) | Additional Symptoms (Some People) |
|---|---|
Balance and movement issues (ataxia) | Autism spectrum disorder |
Epilepsy | Cerebellar atrophy — the brain area controlling posture and balance stops growing or shrinks |
Eye problems such as strabismus (crossed eyes) | Gastrointestinal symptoms, such as GERD |
Inability to speak | Loss of walking skills |
Intellectual disability | Low muscle tone (hypotonia) |
Unusually small head (microcephaly) | Low weight or short stature |
People with Christianson syndrome often have symptoms similar to those of Angelman syndrome. [1] [2] They may seem happy all the time or laugh often for no apparent reason. [1] [2]
Females who have the gene mutation often have learning disabilities. [1] But they typically don't have any other Christianson syndrome symptoms.
What Causes Christianson Syndrome?
Christianson syndrome is a genetic disorder, meaning it occurs because of a gene mutation. Christianson syndrome happens when someone is born with a mutation in their SLC9A6 gene, a gene in their X chromosome. [1] [4]
This gene mutation is passed down from parent to child. Usually, parents who pass down the mutation are carriers of Christianson syndrome, meaning they have the gene change but don't have any symptoms of the condition themselves. [1]
How Is Christianson Syndrome Diagnosed?
Your healthcare provider may suspect Christianson syndrome if you or your child has several of its symptoms. They use a blood test to diagnose or rule out Christianson syndrome. This blood test checks for the SLC9A6 gene mutation. [1]
How Is Christianson Syndrome Treated?
Christianson syndrome treatment focuses on decreasing symptoms and improving quality of life. You or your child's treatment plan may include eyeglasses, contact lenses or surgery to improve vision or correct crossed eyes; individualized education plans to help children with intellectual or learning disabilities; medications to decrease the number and severity of seizures; physical therapy to increase strength, muscle tone or walking skills; and speech therapy to improve language and communication skills. [1]
Treatment | What It Helps With |
|---|---|
Eyeglasses, contact lenses or surgery | Improve vision or correct crossed eyes |
Individualized education plans | Help children with intellectual or learning disabilities |
Medications | Decrease the number and severity of seizures |
Physical therapy | Increase strength, muscle tone or walking skills |
Speech therapy | Improve language and communication skills |
What Is the Outlook for Christianson Syndrome?
With supportive treatments, people with Christianson syndrome can live a higher quality of life. [1] Research about Christianson syndrome is ongoing, and experts don't have significant data on life expectancy. [1]
Many people with Christianson syndrome live a typical lifespan, although they may experience regression. [1] In regression, speaking or walking skills improve for a period and then worsen.
How Can I Prevent Christianson Syndrome?
There's no way to prevent Christianson syndrome or the gene mutation that causes it. [1] If you suspect you have or are a carrier for Christianson syndrome, you may choose to have genetic testing.
In genetic testing, you give a blood sample to look for certain gene mutations. A genetic counselor reviews the blood test results with you. They help you understand the implications of gene mutations, including your chances of having a child with Christianson syndrome. [1]
What is the bottom line on Christianson syndrome?
Christianson syndrome is a rare, incurable X-linked genetic disorder caused by a mutation in the SLC9A6 gene on the X chromosome. It causes severe nervous system problems — most notably trouble walking and speaking, developmental delays or intellectual disability, and balance issues — and it mostly affects males, because boys with the mutation have no second X chromosome to compensate while girls usually have a functioning backup copy. Symptoms typically appear in infancy and can include ataxia, epilepsy, crossed eyes, inability to speak, microcephaly, and, in some cases, autism spectrum disorder, cerebellar atrophy, GERD, loss of walking skills, hypotonia, and low weight or short stature; some children may also resemble Angelman syndrome in their frequent happy laughter. Skills can follow a pattern of regression — improving for a period and then worsening. Diagnosis is straightforward with a blood test for the SLC9A6 mutation, often prompted by genetic testing of suspected carriers. While there's no cure, a combination of seizure medications, physical and speech therapy, vision correction, and individualized education plans can meaningfully improve quality of life, and many people with the condition live a typical lifespan.
Frequently Asked Questions
What is Christianson syndrome?
A rare genetic disorder. It causes severe problems with your nervous system. It occurs when one or both biological parents pass down a specific gene change (mutation). This condition mostly affects males and leads to intellectual disability, balance issues or loss of speaking skills.
Who does Christianson syndrome affect?
It mostly affects males. The condition is an "X-linked genetic disorder" — it occurs because of a change (mutation) in X chromosomes.
Why does it mostly affect males?
Females have two X chromosomes, while males have one X and one Y. If a male has the gene mutation, they have no other X chromosome to take over typical functions, so they'll develop Christianson syndrome. If a female has the mutation on one X chromosome, they still have one functioning X chromosome, so they aren't likely to develop it. For a female to develop it, they'd need mutations on both X chromosomes — extremely rare.
How common is it?
Extremely rare — experts don't know exactly how many people have it. By some estimates, about 1 in 600 boys have an X-linked intellectual disability, and one study found Christianson syndrome in about 1 in 100 families with a child who had an X-linked developmental disability.
What are the symptoms?
Most males have balance and movement issues (ataxia), epilepsy, eye problems such as strabismus (crossed eyes), inability to speak, intellectual disability, and an unusually small head (microcephaly).
What other symptoms can occur?
Some people also have autism spectrum disorder, cerebellar atrophy, gastrointestinal symptoms such as GERD, loss of walking skills, low muscle tone (hypotonia), and low weight or short stature.
What is ataxia?
Problems with balance and movement. Most males with Christianson syndrome have ataxia.
What is microcephaly?
An unusually small head.
What is hypotonia?
Low muscle tone.
What is regression?
A pattern in which speaking or walking skills improve for a period and then worsen. Many people with Christianson syndrome experience regression.
What is cerebellar atrophy?
When the part of the brain that controls posture and balance stops growing or gets smaller.
How is it similar to Angelman syndrome?
People with Christianson syndrome often have similar symptoms. They may seem happy all the time or laugh often for no apparent reason.
Can females have Christianson syndrome symptoms?
Females who have the gene mutation often have learning disabilities, but they typically don't have any other Christianson syndrome symptoms.
What causes Christianson syndrome?
A gene mutation. It happens when someone is born with a mutation in their SLC9A6 gene, a gene in their X chromosome.
Can parents pass it on?
Yes — the gene mutation is passed down from parent to child. Usually, parents who pass down the mutation are carriers, meaning they have the gene change but don't have any symptoms themselves.
What is a carrier?
Someone who has the gene change but doesn't have any symptoms of the condition.
How is Christianson syndrome diagnosed?
With a blood test that checks for the SLC9A6 gene mutation. Your provider may suspect the condition if you or your child has several of its symptoms.
When do symptoms start?
People often start showing symptoms when they're infants.
Is there a cure?
No. Although there's no cure, treatment can improve overall quality of life.
How is Christianson syndrome treated?
Treatment focuses on decreasing symptoms and improving quality of life: eyeglasses, contact lenses or surgery to improve vision or correct crossed eyes; individualized education plans; medications to decrease the number and severity of seizures; physical therapy to increase strength, muscle tone or walking skills; and speech therapy to improve language and communication skills.
What is the outlook?
With supportive treatments, people can live a higher quality of life. Many people live a typical lifespan, although they may experience regression. Experts don't have significant data on life expectancy, and research is ongoing.
Can Christianson syndrome be prevented?
There's no way to prevent it or the gene mutation that causes it.
What is genetic testing?
You give a blood sample to look for certain gene mutations. A genetic counselor reviews the results with you and helps you understand the implications, including your chances of having a child with Christianson syndrome.
What questions should I ask my healthcare provider?
Ask what tests diagnose Christianson syndrome, what causes it, what the treatment options are, what you can do to improve quality of life, and what the chances are that you'll pass it to your children.
Related Reading
References
Cleveland Clinic. Christianson Syndrome. Cleveland Clinic. Last updated January 20, 2023. https://my.clevelandclinic.org/health/diseases/24648-christianson-syndrome
Morrow E. What is Christianson Syndrome? Christianson Syndrome Association. Accessed October 14, 2026. https://csa-cares.org/what-is-christianson-syndrome/
Genetic and Rare Diseases Information Center. Christianson syndrome. GARD (National Institutes of Health). Last updated September 2026. https://rarediseases.info.nih.gov/diseases/10572/christianson-syndrome
National Library of Medicine. Christianson syndrome. MedlinePlus Genetics. Last updated April 1, 2012. https://medlineplus.gov/genetics/condition/christianson-syndrome/
Jiao JP, Zhang HW, Zhou XZ, et al. Missense variants in SLC9A6 cause partial epilepsy without neurodevelopmental delay. Orphanet J Rare Dis. 2025;20(1):380. PMID 40722028. https://doi.org/10.1186/s13023-025-03924-9
He H, Zhang H, Chen H, et al. Functional analysis of two SLC9A6 frameshift variants in lymphoblastoid cells from patients with Christianson syndrome. CNS Neurosci Ther. 2023;29(12):4059-4069. PMID 37381736. https://doi.org/10.1111/cns.14329
Medical disclaimer
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the guidance of a physician or other qualified health provider with any questions you have about a medical condition. Never disregard professional medical advice or delay seeking it because of something you read here. If you or your child shows several of the symptoms described, talk to a healthcare provider about whether genetic testing is appropriate.
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