Campomelic dysplasia is a type of skeletal dysplasia – a condition where the bones of the skeleton do not form properly before birth. In campomelic dysplasia, the leg bones are bowed – campomelic is the Greek for bent limb. It is a very rare condition, affecting around 1 in every 40,000 births.
As well as the leg bones, other parts of the body are also affected by this condition, some of which are severe enough to be life threatening.
What causes campomelic dysplasia?
Campomelic dysplasia is thought to happen as a result of a sporadic mutation (isolated change) on a particular gene – SOX9 on chromosome 17 – which controls production of the skeleton and reproductive system in the womb. On rare occasions where is it inherited or passed on from parent to child, it is passed on as an autosomal dominant condition. This means that a child has to inherit only one abnormal gene from either parent to have the condition.
What are the signs and symptoms of campomelic dysplasia?
The symptom that causes the most significant problems soon after birth is laryngotracheomalacia. This is a condition where the cartilage rings that hold the windpipe in place are floppy, so the windpipe collapses in on itself causing severe respiratory distress. Sometimes this is severe enough to lead to death.
There may also be confusion over the baby’s gender as the genitals may not look completely male or female. On further investigation, internal reproductive organs may not ‘agree’ with the external genitalia.
The legs are short and bowed; talipes (clubfoot) is also common as are problems with the hip joint. Children may have a small jaw and a cleft palate (Pierre Robin syndrome) and distinctive facial features. Later in life, as the child grows, scoliosis may develop, which can lead to breathing difficulties if untreated, and the bones in the neck can also become unstable. Hearing impairment in later life is also common.
How is campomelic dysplasia diagnosed?
Prenatal diagnosis of campomelic dysplasia is possible, if the bowed legs bones can be identified during an ultrasound scan. After birth, x-rays will be used to diagnose the extent of bone bowing, as will an all-round physical examination to check for any other symptoms associated with campomelic dysplasia. Genetic testing will be needed to determine the baby’s genetic gender.
How is campomelic dysplasia treated?
Initially, babies will need ventilation to deal with the severe respiratory distress caused by the laryngotracheomalacia. Some will need a tracheostomy (opening directly into the windpipe) to be able to breathe unaided.
Once stable, the other symptoms will be confirmed and treated as necessary. This may include surgery to reduce the bowing of the leg bones, correction of talipes with plaster casts and surgery, treatment of any hip problems with bracing and/or surgery and closure of the cleft palate. Once the genetic gender of the baby is known, genitourinary surgery may be suggested either during infancy or later in childhood.
Later in life, spinal surgery may be needed to treat scoliosis as well as to stabilise the neck bones. Hearing impairment will usually be improved using hearing aids.
What happens next?
Children with campomelic dysplasia will require regular long term monitoring, especially of the spine and neck. The numbers of children born with campomelic dysplasia surviving to adolescence and beyond is increasing as we get better at dealing with severe respiratory distress. However, we are now more aware of longer-term problems, such as the spine and neck problems.