Professor Rodney Grahame, CBE, MD, FRCP, FACP, Rheumatology,
Hospital of St John & St Elizabeth, London
EDS is usually described as a ‘rare disease’, that is, a disease which probably occurs in under 1% of the population. Since ‘incidence’ in medical statistics tends to refer to the annual diagnosis rate, and diagnosis of EDS is still extremely difficult to get, there is a possibility that the number of people with EDS is actually greater. One of the complicated things about EDS is that joint hypermobility itself is a fairly common thing. Some estimate that 5% of all children have hypermobile joints. But it is important to realise that not all people with bendy and unusual joint movement therefore have EDS. It may be helpful to think of it in these terms:
Joint hypermobility + symptoms = Ehlers-Danlos Syndrome
In other words, joint laxity along with pain, subluxations (deliberate ‘out-of-jointness’ of various parts of the body), dislocations (of joints), unexplained aches and a whole host of other symptoms may constitute EDS. The disease is caused by an underlying genetically inherited connective tissue disorder. Collagen is such a connective tissue protein in the body and it acts as a ‘glue’ in connecting our tissue and keeping our bodies together. It is vital for skin elasticity and is found in skin, ligaments, tendons and bones as well as all the smooth muscle tissues, blood vessels, digestive tract, heart, gallbladder, kidneys and bladder, and holds the cells and tissues together. It is these connective tissues which seem to be affected in people with EDS and this results in the joints, muscles, tendons and ligaments being laxer and more fragile than in non-hypermobile individuals.
My daughter’s finger
(my fingers do the same)
Whilst it may be easy to recognise unusual joint movements in ourselves and others, it is not so easy to see the effect of connective tissue disorder throughout the rest of the body. EDS not merely about joints. It is systemic. That is, it can affect the whole of the body.
EDS is autosomal dominant. ‘Autosomal’ means that the gene in question is located on one of the numbered, or non-sex, chromosomes. ‘Dominant’ means that a single copy of the disease-associated mutation is enough to cause the disease. What that means is that, if one parent has the gene, it can be passed on to the next generation. There is a 50% chance of inheriting EDS. Both my children have EDS from me.
WHAT TERMS DO WE USE TO DESCRIBE THESE CONNECTIVE TISSUE DISORDERS?
IT ALL SEEMS SO CONFUSING.
This might help!
- JHM – Joint Hypermobility. A range of joint movement greater than is normal for most people. This is not a disease or a problem. It might well be a positive advantage for people such as ballet dancers.
- JHS – Joint Hypermobility Syndrome. The ‘syndrome’ gives it away. This means there is a pathology associated with the greater joint movement: pain and body instability. It used to be called Benign Hypermobility, until it was realised this did not properly describe the pain involved in the condition.
- Ehlers-Danlos Syndrome / EDS – There is quite some medical debate about the difference between JHS and Ehlers-Danlos. Many clinicians are now happy to equate JHS with Ehlers-Danlos type III. That is what I shall assume in this blog until more research persuades me otherwise.
TYPES OF EHLERS-DANLOS SYNDROME:
- Classical (EDS types I & II, faulty collagen V): Skin hyperextensibility, velvety skin, wounds slow to heal, joint hypermobility, prolapse, cervical insufficiency, and fragile skin can give hernias.
- Hypermobility (EDS type III): Joint hypermobility, dislocations, joint pains, skin hyperextensibility, POTS (autonomic dysfunction), uterine prolapse, mild mitral valve prolapse.
- Vascular (EDS type IV, faulty collagen III): Arterial/intestinal/uterine fragility or rupture; easy bruising; characteristic facial appearance. May be suggested by family history of early death from dissection or ruptured aortic aneurysm
- Kyphoscoliosis (EDS type VI, caused by abnormal production of the lysyl hydroxylase enzyme): Scoliosis present at birth and progressive; fragility of the sclera of the eye; arterial rupture; Marfanoid body shape; microcomea; skeletal osteopenia on X-ray, club foot at birth.
- Arthrochalasia (EDS type VII): Severe generalised joint hypermobility with dislocations; congenital bilateral hip dislocation.
- Dermatospraxis (part of EDS type VII): Severe skin fragility; sagging, redundant skin, large hernias.
- Tenascin-X Deficient (similar to Classical but without the scarring): Skin hyperextensibility, joint hypermobility, easy bruising, normal scarring. Cf ‘A Recessive Form of the Ehlers-Danlos Syndrome caused by Tenascin-X Deficiency’, Schalkwijk J1, Zweers MC, Steijlen PM, Dean WB, Taylor G, van Vlijmen IM, van Haren B, Miller WL, Bristow J. http://www.ncbi.nlm.nih.gov/pubmed/11642233
See: Ehlers-Danlos Support UK