The Diagnostic Puzzle: Criteria and Biological Basis of hEDS

Understanding how Hypermobile Ehlers-Danlos Syndrome (hEDS) is diagnosed can feel like piecing together a complex puzzle. Because there is no known “hEDS gene” that doctors can test for, they must rely on a set of strict clinical rules called the 2017 International Classification Criteria ^[1][2]. To receive a formal diagnosis, you must meet all three of the following criteria at the same time ^[3][4].

Criterion 1: Generalized Joint Hypermobility

The first step is measuring how flexible your joints are using the Beighton Score ^[2]. A clinician will check nine specific points, such as bending your pinky finger back past 90 degrees, pulling your thumb to your forearm, hyperextending your elbows and knees backward, and your ability to touch the floor with your palms ^[2][5].

Because we naturally become less flexible as we get older, the “passing” score changes based on your age ^[3]:

• Children and adolescents (pre-puberty through teen years): 6 or more points out of 9 ^[6].
• Adults (up to age 50): 5 or more points out of 9 ^[3][2].
• Adults (over age 50): 4 or more points out of 9 ^[3].

It is important to note that the Beighton Score only checks a few specific joints. It misses major joints that frequently dislocate in hEDS patients, such as the shoulders, hips, or the jaw. Many patients have severe instability but “fail” the Beighton score, which can cause intense imposter syndrome ^[5][3].

If your joints have stiffened over time but you were very flexible as a child, your doctor may also use a Five-Point Questionnaire to look at your history of hypermobility ^[2][4][6].

Criterion 2: The “Systemic” Checklist & Family History

This criterion looks for evidence that your connective tissue is affected throughout your whole body, not just in your joints ^[2]. To meet Criterion 2, you must satisfy at least two of the following three features ^[3]:

• Feature A (Systemic Manifestations): You must have at least 5 out of 12 specific physical signs, such as velvety skin, unexplained stretch marks, dental crowding, a high palate, or small bumps on your heels (piezogenic papules) ^[3][7][8].
• Feature B (Family History): Having a parent, sibling, or child who independently meets the 2017 criteria for hEDS ^[3][4].
• Feature C (Musculoskeletal Complications): Having chronic widespread pain or a history of frequent joint dislocations or instability ^[3][2].

Criterion 3: Ruling Out Other Conditions

The final step is to make sure your symptoms aren’t caused by something else ^[2]. This is where genetic testing often comes in. While we cannot test for hEDS, doctors use genetic panels to rule out other serious conditions that look similar, such as:

• Vascular EDS (vEDS): A rare type that affects blood vessels and organs ^[4][9].
• Classical EDS (cEDS): Primarily affects the skin and joints ^[10][4].
• Marfan Syndrome or Loeys-Dietz Syndrome: Conditions that can also cause hypermobility but require different medical monitoring, especially for the heart ^[10][11].

The Biology: Why Is hEDS So Variable?

Scientists are still working to understand exactly what causes hEDS. While other EDS types are caused by clear “typos” in the instructions for building collagen (the body’s main structural protein), hEDS is likely more complex ^[12][13].

Current theories suggest it may involve issues with the extracellular matrix (ECM)—the scaffolding that surrounds our cells—or how the body’s fascia (the connective tissue webbing that wraps around muscles and organs) repairs itself ^[13][14]. Because this “scaffolding” is everywhere, it explains why hEDS can affect everything from your vision to your digestion ^[15]. No matter the underlying cause, your symptoms are a result of a physical difference in how your body is built ^[16].