In the spring of 2017, a large group of papers were published in the American Journal of Medical Genetics summarizing the state of knowledge of the connective tissue disorders known as Ehlers-Danlos Syndrome (EDS) and proposed changes in how one of those conditions, specifically Hypermobile EDS (hEDS), is defined [1, 2].

hEDS (formerly known as EDS, Hypermobile Type, or EDS Type III) is the most common type of EDS. While there are currently no good estimates, it is clearly not a rare disorder (“rare” meaning < 1:2,000 people) and it comprises the vast majority of the EDS population.

The new nosological changes are in and of themselves somewhat confusing, and I’m going to attempt to explain them so that the lay community can understand them better. However, more confusing is the fact that many individuals will still have diagnoses that are now obsolete and overlap several diagnostic categories, requiring re-assessment to determine which label is currently most appropriate.

Specifically, Joint Hypermobility Syndrome (JHS) is no longer in use. However, the new diagnostic substitute depends on whether the condition is “benign” (i.e., doesn’t involve musculoskeletal pain/instability). Individuals with “non-benign” forms of JHS will now receive the label, Generalized Hypermobility Spectrum Disorder (G-HSD). People whose primary symptom is generalized joint hypermobility (GJH) (Beighton ≥5 for adults under age 50) and don’t have chronic pain/instability will receive the diagnosis of Asymptomatic Generalized Joint Hypermobility (A-GJH). Obviously, this latter diagnosis can change with age, requiring occasional reassessments.

The criteria for hEDS have also become stricter, placing greater emphasis on collagen deficiency in organ systems in addition to that of the musculoskeletal (e.g., skin, prolapsed organs, heart defects, etc.). This means that many individuals who have diagnoses of EDS, Hypermobile Type or Type III, may no longer make cutoff for the new hEDS definition but would instead be grouped under G-HSD.

While these changes have certainly rattled and confused the hEDS/JHS community, the new nosology also expands the range of diagnoses that can be made, which may ultimately help us in acknowledging a wider range of affected people. Whether or not this new diagnostic scheme remains in longterm use or will continue to change as more research comes to light remains to be seen.

Since the relationship of hEDS, Hypermobility Spectrum Disorders, and generalized joint hypermobility behaves like a complex spectrum condition in that diagnosis can change with age and a range of these diagnoses occur within the same families, I suspect some day these conditions will all be subsumed under a larger umbrella diagnosis that includes the rare severe conditions at one end (Classical EDS, Vascular EDS, etc.), the severe but more common hEDS, followed by the HSDs, and finally benign hypermobility at the other end. Given that conditions such as Postural Orthostatic Tachycardia Syndrome (POTS) and Mast Cell Activation Syndrome (MCAS) occur in conjunction with vascular EDS, classical EDS, hEDS, and other HSDs suggests these conditions do indeed share a strong relationship with one another, despite the EDS diagnostic cutoff, which may ultimately turn out to be arbitrary.

Figure borrowed from Castori et al. (2017) illustrating the proposed spectrum of hypermobility.

According to new nosology, those with hypermobility but who do not meet cutoff for hEDS will be placed into one of two main categories: Hypermobility Spectrum Disorder (HSD) and asymptomatic joint hypermobility.

HSDs are composed of the following diagnoses:

• Generalized Hypermobility Spectrum Disorder (G-HSD) – Generalized joint hypermobility plus musculoskeletal pain and/or instability. This replaces the previous diagnosis of “non-benign” JHS.
• Peripheral Hypermobility Spectrum Disorder (P-HSD) – Joint hypermobility in the peripheral joints (hands, feet) plus pain and/or instability.
• Localized Hypermobility Spectrum Disorder (L-HSD) – Joint hypermobility limited to single joints or body parts plus pain and/or instability.
• Historical Hypermobility Spectrum Disorder (H-HSD) – A history of joint hypermobility plus current pain and/or instability.

Meanwhile, “benign” forms of joint hypermobility include:

• Asymptomatic Generalized Joint Hypermobility (A-GJH) – Generalized joint hypermobility without pain or instability. May change with age. Replaces previous diagnosis of “benign” JHS.
• Asymptomatic Peripheral Joint Hypermobility (A-PJH) – Peripheral joint hypermobility without pain or instability.
• Asymptomatic Localized Joint Hypermobility (A-LJH) – Joint hypermobility limited to single joints or body parts, without pain or instability.

So to summarize:

1. There is now recognition of a spectrum of joint hypermobility, acknowledging the existence of conditions that don’t include current generalized joint hypermobility but a history of the same or fewer affected joints. In addition, these conditions are divided according to the presence of a “disorder,” referring to the occurrence of musculoskeletal pain/instability. When this type of impairment is present, a Hypermobility Spectrum Disorder diagnosis is given. When the hypermobility appears benign and a “disorder” is not currently present, an asymptomatic joint hypermobility diagnosis is used. These latter diagnoses may change with age.
2. Joint Hypermobility Syndrome is now an obsolete diagnosis. “Benign” JHS is now known as Asymptomatic Generalized Joint Hypermobility, while “non-benign” JHS is referred to as Generalized Hypermobility Spectrum Disorder.
3. The name for Ehlers-Danlos Syndrome, Hypermobile Type or Type III, has now changed to Hypermobile Ehlers-Danlos Syndrome. The criteria for hEDS have also tightened to place greater emphasis on organ systems besides musculoskeletal, such as skin, heart, etc. For this reason, a portion of individuals with Hypermobile Type/Type III diagnoses will no longer make cutoff for hEDS and would instead receive diagnoses of Generalized Hypermobility Spectrum Disorder if re-assessed.

Well, I hope this explanation has been helpful and clears up some of the confusion. Admittedly, some of the changes in nosology have proven mind-boggling for patients and doctors alike. However, the fact that there is now recognition of a broader spectrum of conditions is promising. While I don’t think the division between EDS, HSDs, and asymptomatic joint hypermobility will remain as it’s currently written, this is another step forward in the recognition of these conditions as a single, potentially related spectrum.

For now, definitions have tightened, which I know many are not happy about. But as with most diagnostic arguments in medicine concerning complex conditions, the pendulum will undoubtedly swing the other way again in future. Hopefully sooner rather than later.