To complicate matters further, there’s emerging evidence that hEDS commonly co-exists alongside other conditions (known as comorbidities), particularly, as in Ellie and Dr Reinhold’s cases, MCAS (an immunological condition where cells from the body’s immune system inappropriately release chemicals that trigger inflammatory reactions), PoTS (a form of autonomic dysfunction, where your heart rate increases very quickly after getting up from sitting or lying down), and other dysfunctions of the autonomic nervous system.