Coffin Siris Syndrome

Overview

Coffin-Siris syndrome (CSS) is a rare genetic condition that affects how a child grows and develops. It is present from birth. Children with CSS often have developmental delay, speech difficulties, and particular physical features, such as sparse scalp hair, thick eyebrows, and small nails. The pattern and severity vary a lot from person to person. CSS is not caused by anything a parent did or did not do.

CSS is rare. Exact numbers are not known, but it is considered a very uncommon condition.

CSS can affect boys and girls and people of all ethnic backgrounds. It is usually found in babies and children, but it is a lifelong condition, so adults can have CSS too.

Symptoms

Common symptoms

• Developmental delay or intellectual disability, meaning learning and problem-solving may take more time
• Speech delay, limited speech, or no spoken words in some children
• Physical features such as thick eyebrows, long eyelashes, a wide mouth, full lips, and sparse scalp hair
• Small or missing nails, especially on the fifth finger or fifth toe
• Low muscle tone, which can make sitting, crawling, or walking later than expected
• Feeding difficulties, slow growth, or constipation
• Seizures in some children
• Hearing or vision problems
• Sleep problems and behavior differences

Symptoms in children

• Delays in rolling, sitting, crawling, walking, or using hands
• Speech and language delay; some children use signs, pictures, or communication devices
• Feeding problems, reflux, or trouble gaining weight
• Constipation and toilet-training difficulties
• Frequent ear infections or breathing infections in some children
• Dental problems, such as late teeth or crowded teeth
• Sensitivity to noise, touch, or busy places in some children

Causes

Main causes

• CSS is caused by changes in genes that help control how the body develops. These genes are part of a group called the SWI/SNF complex. The most common gene involved is ARID1B.
• In most children, the gene change happens randomly around the time of conception. This is called a new or de novo change. It is not caused by the parents' health, diet, or lifestyle.
• Less often, a gene change is inherited from a parent. A genetic counselor can explain the chance of this in your family.

Risk factors

• Having a family member with a known CSS gene change, which is uncommon
• No known preventable risk factors; most cases happen without any family history
• The gene change is present before birth, so nothing during pregnancy is known to cause it

When to see a doctor

See a doctor urgently if:

• Your child has a first seizure
• Your child is breathing quickly, struggling to breathe, or looks blue
• Your baby is not feeding, is very sleepy, or has signs of dehydration
• Your child has severe belly pain, vomiting, or no bowel movement for several days with swelling
• Your child loses skills they used to have

Book a routine appointment if:

• You are worried about your child's speech, learning, or movement
• Your child has feeding, growth, or constipation problems
• Your child has sleep problems, behavior changes, or frequent infections
• You notice unusual physical features or small nails and want advice
• You want to discuss genetic testing or family planning

Diagnosis

Doctors suspect CSS after looking at a child's development, health history, and physical features. A genetic test can confirm a change in one of the genes linked to CSS. A clinical geneticist or pediatrician usually leads this process.

Tests that may be done

• Genetic testing using a blood or saliva sample, such as a gene panel, exome sequencing, or genome sequencing
• A developmental and behavior assessment by a pediatrician or child development team
• Hearing tests and vision checks
• Brain imaging, such as an MRI, if seizures or unusual head size are present
• EEG, a painless test that records brain waves, if seizures are suspected
• Heart ultrasound and kidney ultrasound, as some children have structural differences
• Sleep study if sleep problems or breathing problems during sleep are suspected
• Blood tests to check growth, nutrition, and general health

What to expect at your appointment

You may be referred to a genetics team and a child development team. Test results can take several weeks. The results may help explain your child's needs, guide health checks, and connect you with the right support. A genetic result does not tell you exactly how severely your child will be affected.

Treatment

There is no cure for CSS. Treatment focuses on supporting development, treating health problems, and helping the child and family live well. Every child's plan is different and should be made with a team of health professionals.

Self-care at home

• Keep a simple routine for sleep, meals, and medicines prescribed by your child's team
• Follow advice from feeding and speech therapists about safe textures and positions for eating
• Set up a gentle constipation plan with your doctor, including fluids, fiber, and toilet routines
• Care for skin, hair, and nails gently, and check for ingrown nails or infections
• Use safety gates, helmets, or other aids if your child is prone to falls
• Keep a diary of seizures, sleep, eating, or behavior patterns to share with your doctor

Medical treatments

Treatment is tailored to your child's needs. It may include speech and language therapy, occupational therapy, physical therapy, special education support, and help with feeding and growth. Hearing aids or glasses may be offered if needed. Seizures, constipation, sleep problems, and infections are managed by the appropriate specialists using treatments they recommend. Regular checks with a pediatrician or family doctor help catch problems early. A genetic counselor can discuss family planning and testing options.

When is surgery considered?

Surgery is not a treatment for CSS itself. It may be considered for specific problems, such as a hernia, cleft palate, severe feeding problems that need a feeding tube, or other structural issues. Your child's specialist team will discuss benefits and risks if surgery is suggested.

Living with this condition

Daily life with CSS often involves therapy appointments, school planning, and health checks. A predictable routine, clear communication, and a team that knows your child can help. Many families find it useful to keep one folder or phone note with reports, medicines, and contact details.

Lifestyle tips

• Build a calm, predictable routine for meals, sleep, and activities
• Use visual schedules, simple words, or signs to help communication
• Encourage play and movement that your child enjoys and can do safely
• Plan breaks in busy or noisy places if your child is sensitive to stimulation
• Stay connected with school, therapists, and your support network

Diet and exercise

Offer a balanced diet with plenty of fluids and fiber, and ask your doctor or dietitian for advice if constipation or slow growth is a concern. Physical activity should be adapted to your child's abilities. Swimming, walking, dancing, and play can help strength, balance, and mood. A physiotherapist or occupational therapist can suggest safe activities.

Mental health and emotional wellbeing

Caring for a child with a rare condition can bring stress, worry, and grief, and that is normal. Children may also feel frustrated or left out. Talking to a counselor or joining a support group can help. If you or a caregiver have thoughts of harming yourself, contact your local emergency number or a crisis support service right away.

Prevention

CSS cannot be prevented. It is caused by a gene change that is usually present before birth and is not linked to anything a parent did during pregnancy.

Vaccines

No vaccine prevents CSS. Your child should receive routine vaccines as advised by your health team, just like any other child.

Screening programmes

Early developmental checks, hearing tests, vision tests, and regular health visits can help find problems early. If a family gene change is known, a genetic counselor can discuss testing options before or during pregnancy.

Complications

If left untreated

• Longer-lasting developmental and speech difficulties
• Seizures that are not controlled
• Feeding and growth problems, or dehydration
• Ongoing constipation and bowel problems
• More frequent infections, especially ear or chest infections
• Hearing or vision problems that are missed
• Heart or kidney problems that need monitoring
• Sleep problems and behavior challenges

Long-term outlook

The outlook varies widely. Some people with CSS live full, connected lives with support, while others have more complex health needs. Early therapy, regular health checks, and a strong support team can help your child reach their potential. Your healthcare team can give you a clearer picture based on your child's specific needs.

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