Types of EDS
The Ehlers-Danlos syndromes are a group of genetic connective tissue disorders which are currently classified in a system of thirteen types. Despite this grouping and their common name, each type is a distinct condition caused by a different gene mutation. This means that a child cannot inherit a different type of EDS to the one their parent has. It also means that one type cannot later turn into another; and there is no increased risk of having another type just because you have one – they are simply not connected. It is also extremely unlikely that one person would have more than one type, given the rarity of most of these illnesses.
Recently some of the criteria used to diagnose the Ehlers-Danlos syndromes and some of the terminology describing them changed, in order to reflect scientific research from the past twenty years. The 2017 EDS International Classification recognises thirteen types of EDS and defines for the first time some related conditions, the hypermobility spectrum disorders (HSD) which have similar symptoms to hypermobile EDS (hEDS). The term joint hypermobility syndrome (JHS) is no longer used.
The most common type of EDS is thought to be the hypermobile type (formerly known as the hypermobilty type or type 3) although the exact prevalence of this condition is not currently known. The medical literature states that it affects 1 in 5,000 people however this statistic is based on research that is out-of-date and hEDS/HSD frequently go undiagnosed or are misdiagnosed as other conditions. HSD and possibly hEDS are likely to be common. The classical and vascular types are rare, with other types being rarer still. It is probable that all the types are underdiagnosed to some degree.