Spondyloepiphyseal dysplasia (SED) is a rare, genetic condition that affects bone growth in the spine, arms and legs. It can also cause problems with eyesight and hearing.
There are two types of spondyloepiphyseal dysplasia:
- congenita – this is present from birth.
- tarda – where a child may appear normal at birth but show symptoms of the condition later in life; perhaps as late as when they go through puberty.
Approximately one in 100,000 babies are affected by spondyloepiphyseal dysplasia.
What causes spondyloepiphyseal dysplasia?
Spondyloepiphyseal dysplasia congenita is caused by a mutation (change) in the COL2A1 gene.
The COL2A1 gene helps produce a protein that is essential for the normal development of bones and connective tissues – without this protein, the bones and tissues will not develop properly. There is usually no history of spondyloepiphyseal dysplasia in the family.
Spondyloepiphyseal dysplasia tarda is hereditary – it may affect either the autosomal or sex chromosomes. In some families it only affects the boys.
What are the signs and symptoms of spondyloepiphyseal dysplasia?
Children with spondyloepiphyseal dysplasia usually have a shorter body, neck and limbs than other children their age. As an adult, they may only grow to be three or four feet tall.
They may also have other bone abnormalities, for example:
- a curve of the spine (scoliosis)
- flattened vertebrae (the bones around the spinal cord that make up the spine)
- a hip condition associated with an excessive bend in the upper part of the thigh bone which limits the amount of movement the hips have (coxa vara)
- a problem with the position of the feet at birth (a possible talipes equinovarus deformity may be seen)
- pain in the joints and bones (arthritis)
- a decreased range of movement
The face may also be affected, for example:
- flattened cheekbones and/or a characteristic facial appearance
- an opening in the roof of the mouth (a cleft palate)
- vision problems
- hearing loss
Boys with spondyloepiphyseal dysplasia tarda might experience back and hip pain as they go through puberty. They might also develop osteoarthritis (swollen or damaged joints) in their shoulders, hips or back and have difficulty walking.
How is spondyloepiphyseal dysplasia normally diagnosed?
Spondyloepiphyseal dysplasia may be picked up during pregnancy at one of the routine ultrasound scans.
After birth, or in early childhood if there are concerns, a doctor will examine a child and take relevant X-rays to confirm any suspected bone abnormalities.
How is spondyloepiphyseal dysplasia normally treated?
The child might need a back brace to support their spine, or surgery to correct curved bones. The doctor will talk through all the available treatment options with parents and their child.
Regular X-rays may be needed, to keep an eye on how the bones and joints and spine are developing.
Between check-ups, if the child complains of muscle pain, unexplained tiredness, difficulty controlling their bowels or a tingling sensation in their arms or legs, a doctor should be contacted. These symptoms may indicate that the spinal cord is becoming irritated or compressed.
What happens next?
The child may need to avoid weight-bearing activities such as football, skating or bowling if symptoms of pain and stiffness in the muscles and joints are to be kept to a minimum.
However, swimming can help strengthen their muscles which in turn will help support their bones and joints.
The child might need joint replacement surgery (hip, knee or shoulder) as early as age 30.