Dwarfism: what it is, types, causes and support in the UK

The Restricted Growth Association (RGA), the UK charity for people with restricted growth, says dwarfism is commonly described as having a final adult height of 4 feet 10 inches or less due to a medical condition. It is not one condition but a result of many different conditions, most of them genetic. The RGA uses both the terms restricted growth and dwarfism, and estimates that around 6,000 people in the UK live with a restricted growth condition.

The RGA says most people with restricted growth conditions have normal intelligence and normal life expectancy, although health problems linked to a specific condition may need monitoring.

The RGA divides restricted growth into two broad groups. In proportionate short stature the trunk stays in normal proportion with the legs but there is a general lack of growth throughout the body. In disproportionate short stature there is a problem with the way joints and bones grow, so certain limbs may be shorter or there may be a severe lack of all-over body growth. Disproportionate conditions are usually caused by a genetic condition.

The signs depend on the underlying condition. GOSH describes the features of achondroplasia, which vary from child to child.

• An average-sized body but shorter limbs.

• Bowing of the legs that can appear as the child gets older.

• A larger head with a prominent forehead and a flatter bridge of the nose.

• Very flexible joints, except for the elbows, which may not fully straighten.

• A curvature or kink in the lower back (gibbus, lumbar kyphosis or lordosis).

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

Most causes are genetic. GOSH says achondroplasia is caused by a change in a gene called FGFR3, present in every cell of the body but particularly affecting the growth of the skeleton. The RGA explains that the protein made by FGFR3 normally limits the formation of bone from cartilage, and in achondroplasia the receptor is overly active, which interferes with bone growth.

The RGA says many children with disproportionate short stature have average-height parents and the genetic change occurred spontaneously. GOSH says a person with achondroplasia has a 50% (1 in 2) chance of having a child who also has achondroplasia. Other conditions have different genes and different patterns of inheritance, so a specific diagnosis matters.

GOSH says most cases of achondroplasia are diagnosed shortly before or at birth, because the features cannot be seen on ultrasound before the third trimester of pregnancy. Other conditions are recognised later as a child fails to grow at the expected rate or shows disproportion.

Once a diagnosis is made, GOSH says all infants and children with achondroplasia have an MRI scan of the brain and spine, and a sleep study to assess for breathing problems. A referral to the ear, nose and throat (ENT) team may be needed for ear problems.

GOSH says children with achondroplasia can in general achieve independence and success in everyday life, but some health problems can develop at different stages, and professional guidance and treatment can help reduce or manage them.

• Compression of the spinal cord at the top of the neck (foramen magnum stenosis), a serious condition that can cause breathing difficulties and in some cases sudden infant death if not detected early. GOSH says a lie-flat car seat is important and affected babies are referred to a neurosurgeon.

• Lower back curvature that can get worse if a baby is encouraged to sit upright before they are ready.

• Ear infections and glue ear, which are more common because of the shape of the passage between the mouth and middle ear.

• Breathing problems during sleep, which are assessed with a sleep study.

There is no single treatment, because there are many causes. GOSH says children with achondroplasia are cared for by a specialist consultant in a multidisciplinary team. They benefit from occupational therapy and physiotherapy, a clinical nurse specialist and psychology support.

GOSH says neurosurgery may be recommended to correct spinal stenosis, corrective or reconstructive orthopaedic surgery can help with significant curvature of the spine, arms or legs, and ENT surgery can help with repeated ear infections, glue ear or hearing difficulties. It also says different drug therapies have been used internationally which are not yet available on the NHS, and some UK centres take part in drug trials for achondroplasia.

GOSH gives specific advice for babies. It says not to encourage a child to sit upright too early, even with support, as this can make the spinal curve worse, and recommends plenty of floor play, tummy time and supported positions until the baby is strong enough to sit unaided. Babies should be held with a flat spine, avoiding a C-shaped curve, and infant bouncers, swings, soft rockers, baby walkers and most carriers should be avoided.

For weaning, GOSH says seating should recline to 30 degrees from upright with firm back support, used only at mealtimes for up to 20 minutes. Because of the risk of breathing difficulties, it recommends that parents have training in basic child life support.

Because of the risk of breathing problems in some babies, GOSH says parents should have basic child life support training. The NHS advice on shortness of breath says to call 999 or go to A&E immediately if a child has difficulty breathing (they may make grunting noises or suck their stomach in under the ribcage), has lips or skin turning very pale, blue or grey, is suddenly confused, or is limp, floppy or not responding as normal.

For concerns about growth or development, speak to a GP or health visitor, who can refer your child to a paediatrician.

The RGA says its purpose is to ensure that all people affected by dwarfism are equal in society. It provides information for parents, a membership community and events. GOSH says some families find it helpful to link with support groups to share experiences with other parents, carers and children with achondroplasia and restricted growth.

On the NHS, a GP or health visitor refers concerns about growth to a paediatrician, and specialist skeletal and genetic services provide multidisciplinary care for conditions such as achondroplasia. Some people also seek private paediatric endocrinology or genetics opinions for diagnosis.

Whichever route you use, ask which condition has been diagnosed and whether genetic testing was done, because the specific diagnosis determines the monitoring needed and the chance of passing the condition on.