Achondroplasia is a condition where the bones do not grow as much as usual. People with achondroplasia are usually healthy but short. About 1 in 25 000 babies born in the UK has achondroplasia. Sometimes scans during pregnancy will have picked up that the baby’s bones are shorter than usual. Often, once a baby is born a problem with their bones is suspected. X-rays and a genetic test will usually be done to make the diagnosis.
Achondroplasia can be caused by several different medical conditions. Some children with restricted growth may be eligible for treatment with human growth hormone.
There are two main types of restricted growth:
If someone has PSS, the length of their trunk (abdomen and chest) will be in normal proportion with the legs, but they will have a general lack of height. The most common cause of PSS is being born to small parents. PSS can also occur when the body does not produce enough growth hormone.
DSS occurs when there is a problem with the way joints and bones grow. Certain limbs may be shorter, or the trunk may be particularly short. Generally, there may be a severe lack of height. Conditions associated with DSS are usually caused by a faulty gene. Many children born with DSS have parents of average height and the faulty gene occurred by chance. Girls with Turner syndrome and children with a genetic abnormality known as SHOX gene haploinsufficiency have a mild form of DSS. Around 30,000 people in the UK have a restricted growth condition that causes DSS. Treatment will depend on the cause of short stature and is likely to involve many different types of healthcare professionals. If the legs are particularly short, DSS can be treated with a leg-lengthening procedure, although there is uncertainty about the safety and effectiveness of this.