Noonan syndrome

Noonan syndrome (NS) is a complicated genetic condition. Diagnosing NS has been described as doing a jigsaw puzzle without knowing what the final picture is. This is because there are many different signs and symptoms which point to NS but every patient has a different combination.

It is thought that between one in 1,000 and one in 5,000 people have NS

What causes Noonan syndrome and who can get it?

Genetic problems cause NS. In around half the cases, these faulty genes are inherited from your parents. In the other half, the genetic code, which tells your body’s cells how to grow, makes a bad copy of itself. This can happen without any family history of the condition.

NS affects girls and boys equally and occurs in all races and areas of the world. People with NS are born with the condition.

What are the signs and symptoms of Noonan syndrome?

Some of the signs and symptoms of NS are a bit like a pick and mix – there are many different ones and each patient has their own unique combination. However, heart complaints are common to 90 per cent of people with NS.

It is also worth remembering that the signs and symptoms change over time and usually become much less noticeable as you get older.

Some of the possible signs and symptoms are:

Heart problems – people with NS often have a heart condition as well – usually pulmonary stenosis.
Eyes – large, round and downward sloping with heavy eyelids (ptosis). Sometimes there is a large gap between the eyes.
Ears – set low on the head and may be twisted so earlobes point forward.
Nose and forehead – wide forehead and a flat bridge of the nose.

Neck – short with tight skin or ‘webbing’ on the sides. This can make the shoulders look rounded.
Hair – coarse, curly hair with a low hairline on the back of the neck and a ‘trident’ hairline on the forehead is quite common.
Feeding – babies with NS often struggle to suck and take a long time to start eating solid food. Vomiting is common, as well as a strong dislike for certain foods.
Speech – development can be delayed.
Vision – short-sightedness, squints and astigmatisms are fairly common.
Growth – people with NS are often quite short and light for their age.
Puberty – boys often have undescended testicles and puberty is delayed for boys and girls.
Bruising and bleeding – there can be problems with blood clotting which leads to easy bruising.
Skin – dry patches of skin are common. There might also be raised brown freckles.

The signs and symptoms are usually obvious from birth or early childhood. They usually soften over time, and older children and adults with the condition don’t normally stand out in a crowd or look different in any way.

How is it normally diagnosed and treated?

NS is often diagnosed over time as the signs are spotted and linked together by doctors. However, there is a test for one of the genes which is responsible for causing the conditions (PTPN11). This is a very specialised blood test and the results take one month to come through.

If there is a history of NS in a family, doctors can test a baby before it is born. This can tell them if the faulty gene is there but it can’t predict how severe the case will be. An ultrasound scan on the unborn baby will be able to check for any heart problems.

Treatment involves a combination of surgery, medicine and therapy. Exactly what is done varies from case to case. Many of the problems become less noticeable as the patient gets older.

When should I seek medical help?

Treatment will start early in life and it is important to have regular check-ups as you get older. In particular, heart problems should be carefully monitored.

Looking forward

Many of the signs and symptoms soften over time and older teenagers and adults with NS don’t stand out. However, teenagers with NS go through puberty later than their friends and this can make them feel isolated or insecure.

It is important that boys with undescended testicles are treated as early as possible to reduce the risk of infertility.

As people with NS get older they can develop arthritis. Also, heart problems might mean that the immune system is weak and so people with NS might be more likely to catch colds or the flu.

Life expectancy for people with NS is the same as normal.

For more help and information

The charity BDF Newlife has factsheets and support services for people with Noonan syndrome and their families. Visit their website at www.bdfnewlife.co.uk

You can speak to a BDF nurse on 08700 70 70 20.

Last reviewed by St Georges Hospital medical school: 30 November 2007