Link between MCAS, POTS, and Symptomatic Hypermobility

Among neurodivergent people, a commonly-heard diagnosis besides Ehlers-Danlos Syndrome (EDS) and Hypermobility Spectrum Disorder (HSD) is Mast Cell Activation Syndrome (MCAS).

There is significant overlap in the symptoms of MCAS, Postural Orthostatic Tachycardia Syndrome (POTS), and symptomatic hypermobility such as hypermobile EDS (hEDS) and HSD, which are thought to form a cluster (Cheung & Vadas, 2015).

The diagram, adapted from Figure 3 in Kohn & Chang, 2020, shows the interrelation between MCAS, POTS, and symptomatic hypermobility, with common symptoms including fatigue, abdominal pain, constipation, diarrhea, low blood pressure, headaches, and palpitations. In the diagram, I have intentionally refrained from using the terms HSD and EDS, recognizing the challenges associated with obtaining a diagnosis for these conditions. This includes factors such as limited access to diagnostic resources and a scarcity of experts in the field.

EDS impacts the connective tissues, and mast cells, which are a type of white blood cell, are found within these connective tissues. Given this, it is plausible that the presence of EDS could affect the behavior of mast cells, and conversely, mast cells might influence the manifestation of EDS. Research suggests a potential link between EDS and MCAS. MCAS is particularly common in people with hEDS and HSD (e.g., Monaco et al., 2022).

A common saying in the EDS community is, 'If you can't connect the issues, think connective tissues.'

Medical professionals need to understand that behind the diverse, unexplained physical symptoms of neurodivergent people may lie connective tissue disorders such as EDS, MCAS, and POTS.