Marfan syndrome - Diagnosing Marfan syndrome

Marfan syndrome can be difficult to diagnose because the signs and symptoms can vary from person to person.

In most cases, a diagnosis will be based on a thorough physical examination and a detailed assessment of a person's medical and family history.

There are a number of criteria that your GP or geneticist (gene specialist) will measure your symptoms against.

Physical examination

Your GP will carry out a physical examination, which will include:

• listening to your heart
• checking your skin for stretch marks
• looking for any physical features of the syndrome, such as long, thin arms

As well as the varied symptoms of Marfan syndrome, it can sometimes be difficult to distinguish the syndrome from other syndromes that affect the body's connective tissue, such as Ehlers-Danlos syndrome or Beals syndrome.

The Marfan Foundation has more infomation about disorders that are related to Marfan syndrome.

Medical history

As well as carrying out a physical examination, your GP will have a detailed look at your:

• medical history – to find out whether you've had any symptoms or illnesses in the past that may be a sign of Marfan syndrome
• family history – if you have a close family member with Marfan syndrome, your chances of also having the syndrome are increased 

Children

Marfan syndrome can be particularly difficult to diagnose in children and it's very rare for it to be diagnosed in a young child. This is because most of the syndrome's signs and symptoms don't usually appear until the teenage years.

If Marfan syndrome is suspected, your child will be carefully monitored so that any developing symptoms can be detected and treated as soon as possible.

Ghent criteria

Your GP may compare the signs and symptoms against the Ghent criteria. This is a diagnostic tool that helps GPs and other healthcare professionals tell the difference between Marfan syndrome and other similar syndromes.

The Ghent criteria consist of major and minor criteria. The major criteria are features or symptoms that are common in people with Marfan syndrome and rare in people who don't have the syndrome.

Minor criteria are features or symptoms that are present in people with Marfan syndrome, but are also present in people who don't have it.

To be diagnosed with Marfan syndrome using the Ghent criteria, you must have a number of different symptoms.

If you have a family history of Marfan syndrome, you'll need to have one of the major criteria and one of the minor criteria.

If you don't have a family history of Marfan syndrome, you'll need to have two major criteria and one of the minor criteria. 

Some of the different criteria that your GP may use are outlined below.

Major criteria

Major criteria can include:

• an enlarged aorta (main artery)
• a tear in the aorta
• dislocation of the lens of the eye
• a family history of the syndrome
• at least four skeletal problems, such as flat feet or scoliosis (curved spine)
• dural ectasia (enlargement of the lining that surrounds part of the spinal cord)

Minor criteria

Minor criteria can include:

• myopia (short-sightedness)
• unexplained stretch marks
• loose joints
• a long, thin face
• a high, arched palate (roof of the mouth)

Further testing

Your GP may arrange for you to have some additional tests at a hospital or clinic. This will help detect any potentially serious symptoms, such as an enlarged aorta. Some of the tests that you may have include:

• an eye examination – this is carried out by an ophthalmologist (a doctor who specialises in eye conditions) to check for dislocation of the lens
• an echocardiogram – this uses sound waves to produce an image of your heart and can also check for any problems with your aorta
• a chest X-ray – an imaging technique that uses high-energy radiation to highlight abnormalities in bones and certain body tissue, such as the heart and lungs
• a magnetic resonance imaging (MRI) scan – this uses a strong magnetic field and radio waves to produce a detailed image of the inside of your body, and can be used to examine your aorta and other blood vessels and to detect dural ectasia

Genetic testing

Although the gene that causes Marfan syndrome has been identified, it can mutate (change) in more than 1,000 different ways. Genes are single units of genetic material.

A genetic test can be used to examine the gene responsible for Marfan syndrome. It is able to detect an error that causes the condition in 97% of patients.

However, the test is expensive and takes three months to complete.

In most cases, a diagnosis of Marfan syndrome will be made from the physical features and symptoms of the syndrome.

Read more about genetic testing and counselling.

Prenatal testing

If you have Marfan syndrome and you're going to become a parent, you may want to have your unborn baby tested to find out whether he or she also has the syndrome.

To do this, two possible tests can be used – chorionic villus sampling (CVS) or amniocentesis.

Chorionic villus sampling

Prenatal testing for Marfan syndrome can be carried out approximately 10 to 12 weeks into the pregnancy using chorionic villus sampling (CVS).

CVS involves taking a small sample of cells from the placenta (the organ that links the mother's blood supply with her unborn baby's) through the entrance of the womb. The sample can then be tested for genetic conditions.

Amniocentesis

Marfan syndrome can also be tested for using amniocentesis. This test is carried out about 16 to 18 weeks into the pregnancy. It involves taking a small sample of amniotic fluid for examination. Amniotic fluid surrounds the unborn baby in the womb.

Caution

It's important to remember that although prenatal tests may show whether your child has the defective gene, they won't give any indication as to how serious their Marfan syndrome will be.

The severity of Marfan syndrome in the parent is an indication of how severe it will be in the child. Your child may only experience very mild symptoms, despite having the genetic mutation. This is because the expression of the gene can vary, even within the same family. 

In some cases, the results of CVS or amniocentesis could be negative, suggesting that your child doesn't have the defective gene. However, your child may have a different genetic mutation that wasn't tested for that could still cause Marfan syndrome.