Kyphoscoliotic Ehlers-Danlos syndrome
Jessica Bowen & Judy Tocher, Genetic Counsellors, EDS National Diagnostic Service, Sheffield Children's Hospital
Please note: The following text cannot and should not replace advice from the patient's healthcare professional(s). Any person who experiences symptoms or feels that something may be wrong should seek individual, professional help for evaluation and/or treatment. This information is for guidance only and is not intended to provide individual medical advice.
The information in this article is based on the experience and expertise of the UK’s EDS National Diagnostic Service.
Kyphoscoliotic Ehlers-Danlos syndrome (kEDS) is one of the rarer types of EDS which was formerly known as EDS type VIa. As with all the rare types of EDS, the information available in the medical literature is based on a fairly small number of cases. Most doctors will never see a patient with this condition in their whole working lives.
What are the main features of kyphoscoliotic EDS?
Babies with kyphoscoliotic EDS are very floppy because of poor muscle tone. This means they may be late reaching their motor milestones such as sitting and walking. It is not unusual for young children to be investigated for neuromuscular disease because of the severity of floppiness. In older children there may be difficulties with walking.
The joints are very hypermobile and can be unstable leading to frequent dislocations.
The skin may be stretchy, soft and bruise easily. The skin may also be more fragile and form widened, atrophic scars.
The upper part of the spine develops a curve which may cause a hunched appearance and the chest may look asymmetrical. Medically this is termed a kyphoscoliosis. Typically this starts in childhood and slowly becomes more pronounced. It often requires orthopaedic surgery.
The transparent part of the eye at the front is called the cornea. In kyphoscoliotic EDS the cornea may be smaller than usual. Very rarely, the eyeball may rupture because of fragility of the wall of the eyeball.
Occasionally other features have been reported including:
- Individuals are tall and thin with long fingers and toes.
- Reduced bone mass (osteopenia) but with no increased occurrence of bone fractures.
- Fragile artery walls that may increase the risk of medium-sized arteries rupturing.
What is the cause of kyphoscoliotic EDS?
This type of EDS is caused by the lack of an enzyme called lysyl hydroxylase. This enzyme is needed in the formation of the protein collagen. Collagen is one of the proteins found in the connective tissues. These tissues act as a ‘glue’ in the body and provide support and add strength and flexibility. When the enzyme produced is faulty or there is not enough working enzyme, then cross-links between the individual collagen fibres are not made properly. This leads to unstable cross linking and weakened collagen which in turn weakens the connective tissues.
How can the diagnosis be made?
The diagnosis of kyphoscoliotic EDS is made by a multi-step process. Firstly, a thorough medical history and physical examination will be needed. Someone with signs and symptoms of kyphoscoliotic EDS can then have tests to confirm the diagnosis.
- Urinary cross-links: a urine sample is taken and analysed for the presence of collagen cross-links. Someone with kyphoscoliotic EDS will always have an abnormal result.
- Genetic test: a blood sample is taken to provide a sample of DNA (genetic material). This is then used in the laboratory to look for alterations in the PLOD1 gene. This gene is the instruction for making the enzyme lysyl hydroxylase.
When someone is suspected to have kyphoscoliotic EDS, it is important that they are seen in a specialist centre so that the appropriate examination and tests can be offered. Referrals may be made by an NHS hospital consultant to the EDS National Diagnostic Service.
Why does no-one else in my family have similar problems?
It is often the case that only one person in a family is diagnosed with this condition, but it can affect both girls and boys. This is because of the way the condition is inherited. We all have two copies of the PLOD1 gene. One copy is inherited from our mum and the second copy is inherited from our dad. In an affected person, both copies of the PLOD1 gene are altered (like having a spelling mistake in the gene) so that neither copy works properly to make the enzyme. An altered gene copy must be inherited from both parents, who are carriers of the condition. This is called autosomal recessive inheritance. Parents do not have the same condition because they each have a second fully working copy of the PLOD1 gene. In the general population it is rare to be a carrier for kyphoscoliotic EDS and so it is uncommon for both partners in a couple to be carriers. For the parents of an affected child there is a 25% chance of other children inheriting the condition, but the risks in the wider family are very low.
Peer reviewed by: Dr Glenda Sobey, Consultant Dermatologist, EDS National Diagnostic Service, Sheffield Children's Hospital and Carole Cummings, Genetic Counsellor, EDS National Diagnostic Service, Northwick Park and St Mark's Hospitals
Date of last review: 01/04/2016
Date of next review: 01/04/2019