Restricted growth

What is restricted growth (dwarfism)?

Restricted growth means exactly what it says - it is a medical condition causing people to grow less than others, so that they are shorter than those of the same age. It is also called dwarfism, or referred to as 'short stature'. Dwarfism describes a person with an adult height of 4 ft 10 ins (147 cm) or less. You may see people with dwarfism referred to as dwarfs, little people, or people with short stature. These are generally used as descriptions rather than labels.

What causes dwarfism?

Dwarfism is due to a genetic or medical condition, and there are hundreds of causes. In a genetic cause there is a change (mutation) in the genes that form the code in our body's cells upon which all our physical characteristics are based. This can be a mutation inherited from our parents. More often in dwarfism, it happens as a one-off event in the sperm or egg cells from which a baby develops. So in most cases, a person with dwarfism has parents who are a normal height. Usually dwarfism has a genetic cause, but in some cases other medical conditions can cause a problem with growth. This may occur as a baby is developing in the womb or after birth in childhood.

Dwarfism is usually broadly grouped into two different types depending on the body proportions:

• Proportionate: there is a lack of growth in all of the body. All parts of the body are shorter than usual but are in proportion to each other. Other body functions are likely to be affected in addition to the growth process.

• Disproportionate: the main part of the body (the trunk) is a reasonably normal size but the arms and legs are shorter than average. There is usually a genetic cause. This is the type caused by the condition called achondroplasia, which is the most common cause of dwarfism. Usually people with disproportionate dwarfism do not have associated learning disabilities.

Because there are so many causes of dwarfism, it is not possible to list them all here. Some of the more common causes are:

• Achondroplasia. This is a genetic condition causing disproportionate short stature. Upper arms and legs are shorter than average. It usually comes with other typical features such as a prominent forehead and relatively large head, limited elbow movement, and a curved spine. Intelligence and lifespan are not generally affected.

• Diastrophic dysplasia (DTD). A rare genetic condition where limbs are shortened. It tends to be associated with other problems such as a cleft palate, club feet, chest abnormalities and abnormally shaped ears.

• Spondo-epiphyseal dysplasia (SED). This is a group of conditions where the trunk is affected more than the limbs, due to a problem in the connective tissues of the joints. There may be other abnormalities. This may not be obvious at birth and may be picked up as the child grows.

• Pseudoachondroplasia. This is an inherited condition and is likely to run in families. It is not usually apparent at birth, unlike achondroplasia. Limbs are shortened but other typical features of achondroplasia are not present. There is hypermobility of joints and there are often joint abnormalities and problems.

• Turner syndrome. This is a genetic condition affecting girls only. As well as short height, there are typical physical features, and ovaries do not work normally. See the separate leaflet called Turner Syndrome for more information.

• Prader-Willi syndrome. This is a rare genetic condition with many features including learning disability, obesity, muscle difficulties and behavioural problems. It may also cause short stature.

• Noonan syndrome. A rare genetic condition causing many problems as well as short stature. These include heart defects, excessive bleeding, and delays in development.

• Brittle bone disease (osteogenesis imperfecta). A rare genetic condition where bones are not properly formed and break very easily.

• Medical conditions affecting growth. Many medical problems can have an effect on growth. Disorders which affect hormones (particularly growth hormone), major organs (for example, kidney diseases), bones or the body's general functioning (metabolism) can slow growth.

How common is dwarfism?

It is estimated that dwarfism occurs somewhere between one in every 15,000 and one in every 40,000 children born. Achondroplasia is the most common cause. It is the cause in 7 out of 10 people with the condition.

How is dwarfism diagnosed?

This will partly depend on the reason for dwarfism. Babies born with achondroplasia are often diagnosed at birth, simply from their typical appearance. Genetic tests on blood samples may be done to look for other genetic conditions which might have other implications. X-rays may be helpful in some instances. Some people with dwarfism are diagnosed later in childhood, when it is noticed that they are not growing as much as other children of their age. In making a diagnosis, doctors will take into account the pattern of growth, family history, other problems or features, findings on examination, blood tests and sometimes X-rays. Often blood tests for genetic conditions will be needed.

Some genetic conditions are suspected from tests done while the baby is still in the womb, and can be checked by tests done even before birth.

What are the symptoms of dwarfism?

There are no symptoms of dwarfism as such, other than being shorter than others. This may cause practical difficulties throughout life, and may result in children being teased or bullied at school. Short height may affect self-esteem, leading to psychological issues.

If the short stature is part of a genetic condition, there may be associated symptoms, difficulties or medical problems. These vary widely depending on which of the many causes is the reason for the restricted growth.

Possible problems associated with achondroplasia (the most common cause of dwarfism) include:

• Recurring ear infections.

• Obstructive sleep apnoea.

• Crowding of teeth, needing dental treatment.

• Bowed legs causing walking difficulties or joint problems.

• Fluid around the brain (hydrocephalus).

• Back pain and/or numbness in the legs, due to excessive curving of the spine, or narrowed spaces for the nerves to pass through.

• Becoming overweight (obesity).

What is the treatment for dwarfism?

Dwarfism in itself is not a disease that needs a 'cure'. It is a condition which in some cases may be caused by a disease, so sometimes treatments may be needed. For most people with dwarfism, treatment for growth itself is not possible or helpful. Most people will adapt their way of life to cope with their less than average height, but otherwise lead entirely normal lives.

Treatment that might be relevant includes:

• Growth hormone. This is treatment with a hormone medicine which aims to replace the growth hormone normally produced by the body. This is only helpful in a few specific causes of dwarfism where the lack of growth is caused by a lack of growth hormone. It is not helpful for people with achondroplasia. It is a treatment recommended by and managed by a specialist doctor.

• Surgery. Rarely, an operation may be done to lengthen the bones of the legs. This is not commonly done as it involves breaking the leg bones and is a lengthy treatment with a number of risks. Other operations for bones are sometimes needed to correct associated problems. For example, for people with bow legs, operations are sometimes needed to straighten the legs. Operations on the back may be needed to give more space for the nerves to pass through and to relieve pain. Other operations are sometimes needed to correct other associated medical issues, such as to release the fluid around the brain in people with hydrocephalus.

• Team management. For a person with an unusual syndrome resulting in a number of medical problems, often a team of health professionals is involved to help. This might involve physiotherapists, occupational therapists, speech therapists, dieticians, nurses and specialist doctors, just to name a few.

• Support groups. In many countries there are websites for support groups with more information for people either with dwarfism or with the specific conditions causing it. Some of those in the UK are listed in the further reading section below. You can feel rather 'on your own' if you or your child have a very rare condition, and you may find this information and support network very helpful.

What is the outlook?

The outlook (or prognosis) entirely depends on the underlying condition. Overall, most people with dwarfism have no major medical problems, and live full and healthy normal lives. For achondroplasia, life expectancy is normal. However, some of the conditions which cause dwarfism can have associated medical issues which can significantly affect abilities and health.