Cohen Syndrome

Overview

Cohen syndrome is a rare genetic condition that is present from birth. It affects how the body and brain develop. People with Cohen syndrome usually have learning difficulties, weak muscle tone (called hypotonia), a small head size, and a tendency to gain weight around the middle of the body. Many also have eye problems that get worse over time, gum and teeth problems, and a low number of certain white blood cells — the cells that fight infection. The condition is caused by a change in a gene. It is not caused by anything a parent did or did not do.

It is very rare. Exact numbers are not known, but experts think it affects fewer than 1 in 100,000 people worldwide. It is more common in Finland and in a few communities where parents are more likely to share a common ancestor.

Cohen syndrome affects boys and girls equally and is present from birth. Signs often show up in infancy or early childhood. Because it is inherited, it can affect more than one child in the same family.

Symptoms

Common symptoms

• Learning difficulties (intellectual disability), usually mild to moderate
• Weak muscle tone (hypotonia), which can make sitting, walking and feeding take longer to learn
• A small head (microcephaly)
• Weight gain, especially around the tummy, that starts in childhood even when appetite is normal
• Loose, flexible joints
• Typical facial features, such as thick hair and eyebrows, a high bridge of the nose, and eyes that slant slightly downward
• Vision problems, including short-sightedness and changes to the retina at the back of the eye that get worse over time
• A low level of white blood cells called neutrophils (neutropenia), which makes infections more likely
• Gum disease and tooth decay, often starting in childhood
• Speech that develops late or is unclear
• A friendly, sociable manner, which is often a real strength

Symptoms in children

• Floppiness or poor feeding as a baby
• Rolling over, sitting, crawling and walking later than expected
• Frequent infections, such as chest, ear or skin infections
• Slow growth in the first year, followed by weight gain later in childhood
• Delayed speech and language
• Needing extra help at nursery or school

Symptoms in older adults

• Vision may keep getting worse, so regular eye check-ups matter
• Higher risk of weight gain, type 2 diabetes and joint strain
• Gum disease can lead to early loss of adult teeth
• Some adults need help with daily living, work and money matters
• Lifelong check-ups with a GP and specialist team remain important

Causes

Main causes

• Cohen syndrome is caused by changes (variants) in a gene called VPS13B. This gene helps cells sort and move materials inside themselves.
• It is inherited in an autosomal recessive pattern. That means a child needs to inherit one changed copy of the gene from each parent.
• Parents who each carry one changed copy are usually healthy themselves and often have no idea they carry it.

Risk factors

• Having a brother or sister with Cohen syndrome
• Parents who are blood relatives (for example, first cousins)
• Coming from a population where the condition is more common, such as Finland or some closely connected communities
• These factors raise the chance slightly, but the condition is still very rare

When to see a doctor

See a doctor urgently if:

• A fever in a child known to have neutropenia
• Gums that are red, swollen or bleeding, or a tooth that hurts
• New or quickly worsening vision problems
• Any infection that seems to be getting worse rather than better

Book a routine appointment if:

• Your child is not reaching milestones such as sitting, walking or talking at the expected age
• You have noticed unusual weight gain around the tummy
• You or your child's teacher have concerns about learning or speech
• You have a family history of Cohen syndrome and are planning a pregnancy

Diagnosis

Doctors suspect Cohen syndrome from the pattern of features: learning difficulties, weak muscle tone, a small head, weight gain around the tummy, typical facial features and eye problems. The diagnosis is confirmed with a genetic test that looks for a change in the VPS13B gene. A clinical geneticist (a doctor who specialises in inherited conditions) usually guides this process.

Tests that may be done

• A genetic test, usually on a blood or saliva sample, to look for a change in the VPS13B gene
• A full blood count to check the number of white blood cells, repeated over time
• A detailed eye examination, including looking at the retina
• A hearing test
• A developmental assessment to see what support is needed
• Sometimes a brain scan or other tests, depending on symptoms

What to expect at your appointment

Getting a diagnosis can take time, and you may be referred to several specialists. Genetic testing can take weeks to a few months. You should be told what is being tested and what the results might mean. Ask for the results to be explained in plain words, and ask what they mean for other family members.

Treatment

There is no cure for Cohen syndrome. Care focuses on helping the person stay healthy, learn and take part in daily life. Because the condition affects many parts of the body, a team approach works best. The team may include a GP, paediatrician, geneticist, eye doctor, dentist, physiotherapist, speech and language therapist and educational staff. Plans should be reviewed regularly as needs change.

Self-care at home

• Brush teeth twice a day and see a dentist regularly — gum care is especially important
• Wash hands often and keep vaccinations up to date to lower the risk of infection
• Follow the eye care plan and wear glasses or use low-vision aids as advised
• Keep a simple diary of fevers and infections to share with the medical team
• Build in regular physical activity that suits the person's abilities
• Keep a folder of reports and appointments to bring to each visit

Medical treatments

Treatment is put together to match each person's needs. It can include physiotherapy to build strength and movement, speech and language therapy, occupational therapy for daily skills, and extra learning support at school. Eye specialists monitor vision and provide glasses or low-vision help. Dentists treat gum disease and protect teeth. The medical team watches weight and blood sugar and checks white blood cell counts. When infections happen they are treated promptly. In some cases, doctors may suggest medicines that help the body make more white blood cells, or extra steps to prevent infection. All of this is decided together with the specialist team and reviewed over time.

When is surgery considered?

Surgery is not a routine part of treating Cohen syndrome. It may sometimes be needed for specific problems, such as dental treatment, eye conditions, or orthopaedic issues like a curved spine. Any operation needs careful planning with the specialist team, because of the higher risk of infection and the effects of anaesthesia.

Living with this condition

Day-to-day life usually means a steady routine and a team of people who know the person well. Visual schedules, clear simple instructions and plenty of time to practise skills can help a lot. School or work settings should be told about the condition, including the need to take infections seriously and to allow time for eye and dental appointments. As children grow, plans should be updated so that support matches what is needed.

Lifestyle tips

• Keep a calm, predictable routine where possible
• Encourage independence in small steps, such as dressing or making a snack
• Make sure everyone who cares for the person knows about the low white cell count and what to do if a fever appears
• Book eye and dental checks in advance and keep them
• Plan rest breaks, and avoid very crowded places during infection outbreaks if the doctor advises

Diet and exercise

A balanced diet with plenty of vegetables, fruit, wholegrains and protein helps with weight and general health. Because weight gain around the tummy is common, it helps to keep portion sizes steady and limit sugary drinks and snacks, especially for teeth. Regular movement is important too. Choose activities the person enjoys and can do safely, such as walking, swimming, cycling or dancing. A physiotherapist or dietitian can suggest a plan that fits.

Mental health and emotional wellbeing

A rare condition affects the whole family, not just the person with it. Parents often feel exhausted, worried or isolated, and siblings may feel overlooked. Children and adults with Cohen syndrome can feel frustrated when communication or daily tasks are hard. These feelings are normal and deserve support. Talking to a counsellor, joining a carers' group, or asking the specialist team for psychological support can help. If you or someone in your family is struggling to cope or having thoughts of self-harm, contact your local mental health service or a crisis helpline in your country straight away.

Prevention

Cohen syndrome cannot be prevented. It is written into a person's genes from the moment of conception, and nothing a parent did before or during pregnancy caused it. What can be done is to plan ahead. Genetic counselling can explain the chance of having another affected child and the options available, such as testing during pregnancy. Early support for development, vision and dental care cannot stop the condition, but it can reduce its impact.

Screening programmes

There is no routine screening for Cohen syndrome in the general population, because it is so rare. If a child in the family is diagnosed, parents may be offered genetic testing, and testing can be discussed for future pregnancies. Once someone is diagnosed, regular checks of vision, teeth, weight and white blood cell counts act like a screening programme and help catch problems early.

Complications

If left untreated

• Vision can get worse over time, and without eye care some people lose a lot of sight
• Gum disease can lead to early tooth loss and pain
• Infections can become serious in people with a low white cell count
• Weight gain can lead to type 2 diabetes and joint problems
• Without learning and communication support, daily life and schooling become much harder

Long-term outlook

Most people with Cohen syndrome live well into adulthood. Many need support with daily living throughout their lives, and some live more independently. The picture varies a lot from person to person. Early therapy, regular eye and dental care, and quick treatment of infections make a real difference. Families often say that with the right team around them, life is fuller and more positive than they first feared.

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