Achondroplasia

Achondroplasia is the most common form of disproportionate short stature (height). It affects about 1 in 25,000 births.

The condition is caused by a change in a gene called FGFR3. In achondroplasia, the change in this gene is in every cell of the body but particularly affects the growth of the skeleton.

More commonly, achondroplasia is not inherited from parents (the child is the first in their family to have achondroplasia). A person with achondroplasia has a 50% (1 in 2) chance of having a child who also has achondroplasia.

Most cases of achondroplasia are diagnosed shortly before or at birth. This is because the features of the condition cannot be seen on ultrasound before the third trimester of pregnancy.

The features vary from child to child. Typically, children have an average sized body, but shorter limbs.

Bowing of the legs can appear as your child gets older.

Your child may have a larger head with a prominent forehead and a flatter bridge of the nose.

Joints in children with achondroplasia are very flexible, except for the elbows, which may not fully straighten.

The spine often develops a curvature or kink in the lower back. This is called a gibbus, lumbar spine kyphosis or lordosis.

In general, children with achondroplasia can achieve independence and success in everyday life.

Some health problems can develop at different stages of life.

Professional guidance and intervention can help reduce and/or manage complications.

Some infants with achondroplasia have compression of the spinal cord at the top of the neck. This is caused by a narrowing of a channel in the base of the skull called foramen magnum stenosis. It is a serious condition that can cause breathing difficulties and, in some cases, sudden infant death if not detected early enough.

A lie flat car seat is important to reduce the risk of respiratory arrest.

Babies with foramen magnum stenosis are referred to a neurosurgeon as they might need an operation to correct it.

Lower back curvature can get worse if a baby is encouraged to sit upright before they are ready, and the clinical team will offer advice and guidance around managing this.

Due to the shape of the passage between the mouth and middle ear, ear infections and problems such as glue ear are more common in children with achondroplasia.

All infants and children with achondroplasia will have an MRI scan (this uses a magnetic field to take pictures of your child’s body) of the brain and spine.

Your medical team will arrange a sleep study (a test to record what happens to the body when it is asleep) to assess for breathing problems.

A referral to the ENT (Ear, Nose, and Throat) team may be needed if your child is experiencing ear problems.

Early motor milestones are different from other children, because of differences in the way the bones develop, and the head size and shape.

We will give you and your health visitor achondroplasia charts to record growth and development.

Due to the risk of breathing difficulties, it is important that you have training in basic child life support from your local care team.

Do not encourage your child to sit upright too early, even with support, as this can make the spinal gibbus worse. Lots of floor play is recommended until your child is strong enough to sit without support.

While your baby is gaining strength, the recommended positions whilst awake are tummy, side or back. These positions can help the gibbus to resolve on its own.

‘Tummy time’ is recommended for your baby as it will help strengthen their back. It might take time for them to get used to this position and to be able to lift their head, so a small towel placed under their chest as it will give them some support. Practising tummy time frequently but for very short periods of time is recommended to start with.

When being handled and moved between positions, your baby should be held in a supported position with a flat spine, avoiding a 'C' shaped curve.

When lifting and carrying your baby, support the head, neck, and lower back. When your baby needs winding, hold them upright against your chest and avoid putting them in a seated position.

Activity that puts a strain on the neck must be avoided, so please do not use infant bouncers,

swings and trampolines. Do not use soft canvas baby rocker or bouncer chairs, carriers, strollers, or baby walkers as they do not provide enough neck and spine support.

When your baby reaches the weaning stage, seating that reclines to 30 degrees (30°) from upright should be used.

Make sure there is firm support for your baby’s back to help maintain a flat and elongated spine. If a high

chair is not fully supporting the spine, rolled up towels, cushions or pillows can be used to fill gaps.

Seating should only be used at mealtimes for up to 20 minutes and not for any other activity until your baby can sit up by themselves.

At bath time, please support your baby to lie flat in the bath. If seating is used, it must recline to 30 degrees (30°) from upright. Never leave your baby unattended in or near water.

All children with achondroplasia are cared for by a dedicated specialist consultant. Our approach is multi-disciplinary, which means you will have access to a range of specialists who can offer appropriate advice and treatment.

Children with achondroplasia benefit from occupational therapy and physiotherapy to help with their development and participation in everyday life.

Our clinical nurse specialist will support you to make informed choices about your child’s care.

Children, young people and families have access to our psychology services to support many aspects a child’s wellbeing whilst growing up with achondroplasia.

Neurosurgery may be recommended to correct spinal stenosis (narrowing in the spine). Corrective or reconstructive orthopaedic surgery can benefit children with significant problems curvature with the spine, arms or legs.

ENT surgery can help with repeated ear infections, glue ear (a build-up of fluid in the middle ear that can cause hearing loss) or hearing difficulties.

Your child may need to be seen by other specialists outside the multidisciplinary clinic. These referrals can be made if your child needs them.

Different drug therapies have been used internationally which are not yet available on the NHS. Some centres in the UK will be participating in drug trials for achondroplasia.

Some families find it helpful to link in with support groups for meeting up and sharing experiences with other parents, carers and children with achondroplasia and restricted growth. Please ask us for more information about these groups if you would like to know more.

NHS.UK has more information about the condition, symptoms, and treatments.