When I was a medical student, I always found it gratifying when there was a unifying mechanism that explained the symptoms of a disease. Part of the reason I chose dermatology as a specialty was how frequently we are able to “see” these mechanisms in the skin, both clinically and histologically. What’s even more interesting is that this condition is caused by a postzygotic somatic mutation, an apparently underrecognized cause of disease that we are just now beginning to understand. An example of a postzygotic somatic mutation causing a disease that we all learned about in medical school is paroxysmal nocturnal hemoglobinuria.
Dr. Karl Saardi
Using a “bottom-up” approach, researchers at the National Institutes of Health and in the United Kingdom identified 25 patients with somatic UBA1 mutations and noticed that they had strikingly similar autoinflammatory syndromes. UBA1 encodes ubiquitin E1, which is part of the pathway the breaks down proteins as part of the normal cellular machine. It is localized to the X chromosome, so all 25 affected patients were males, and most were aged between 40 and 70 years. These patients had an autoinflammatory syndrome characterized by fever, chondritis (similar to relapsing polychondritis), vasculitis, and neutrophilic dermatoses. Many patients also had features of myelodysplastic syndrome and plasma cell dyscrasia. The inflammatory pattern in this condition seems to show elevations in tumor necrosis factor, interleukin-6, and interferon-gamma.
So why is this syndrome relevant to dermatology? We are often asked to evaluate patients for neutrophilic dermatosis and vasculitis, and many affected patients had clinical and histologic findings compatible with polyarteritis nodosa and Sweet syndrome. When confronted with a neutrophilic dermatosis, we’ve all been taught to evaluate for myelodysplastic syndrome, which many of these patients appeared to have, at least on the surface. When bone marrow biopsies were done, the myeloid cell precursors that give rise to neutrophils were noted to have prominent cytoplasmic vacuoles, hence the “V” in VEXAS.
In reading the article describing 25 patients with this syndrome, which was published in the New England Journal of Medicine, I was struck by how refractory they were to treatment. Most patients had been treated with systemic steroids, multiple biologics, and several nonbiologic medications that are mainstays of treatment for neutrophilic dermatosis like dapsone and colchicine. I was fortunate enough to speak to Amanda Ombrello, MD, of the National Human Genome Research Institute, one of the lead authors of the paper, who drew my attention to the supplementary appendix, which showed the marked injection-site reactions some patients had to anakinra – yet another reason why a patient might end up in a dermatology clinic. In my mind, all of these features could be a clue to a diagnosis of VEXAS syndrome.
Many patients seemed to fare poorly, with 40% of patients dying before the completion of the study. When it comes to extremely rare diseases, it seems that the more physicians who are aware of the existence of a particular syndrome, the more likely it is a patient will come under our care and be correctly diagnosed.
Dr. Saardi is a dermatologist and internist, and is director of the inpatient dermatology service at the George Washington University Hospital, Washington. He has no disclosures.