FMD Chat is pleased to be able to share excerpts from research just published in the Federation of American Societies for Experimental Biology Journal: Clinical and biochemical profiles suggest fibromuscular dysplasia is a systemic disease with altered TGF-B expression and connective tissue features, by Santhi Ganesh, Rachel Morissette, Zhi Xu, Florian Schoenhoff, Benjamin F. Griswold, Jiandong Yang, Lan Tong, Min-Lee Yang, Kristina Hunker, Leslie Sloper, Shinie Kuo, Rafi Raza, Dianna M. Milewicz, and Nazli B. McDonnell.
"Virtually no new information on FMD pertaining to mechanisms of disease has been published in the last 4 decades (5). Currently there is no medical therapy aimed at preventing progression or treating the underlying vascular pathology. Furthermore, there are no biomarkers or defined clinical features to identify who is at risk or who has the disorder... We undertook a deep phenotyping study of 47 individuals with FMD to evaluate relevant genetic, clinical, and anatomic features of this vascular disease...
Recent data have suggested that FMD represents a systemic vasculopathy, with the finding of a clinical manifestation of the disease in multiple arterial beds in at least one-third of patients (20). However, systematic evaluation for clinical and musculoskeletal features has not previously been performed. Our results indicate that FMD is a systemic disease with clinical features that extend beyond arterial pathology to include low bone density, joint laxity, and degenerative disease in the spine. The major clinical manifestations of FMD in our study are related to the vascular pathology and pain often related to early onset arthritis and degenerative joint disease in the spine...
The demographics and clinical histories of our subjects closely align with a U.S. registry of 447 patients with FMD (20) despite differences in study methodologies. We also are aware of 12 subjects enrolled in our cohort who are also enrolled in the same U.S. registry. Similar features included percentage of female sex (91.5 vs. 91.0%), mean age at presentation (44 vs. 47 yr), prevalence of hypertension (66.0 vs. 72.0% at study enrollment), headache (53.2 vs. 60.0%), current or former history of smoking (38.3 vs. 37.2%), and a history of exogenous hormone use (61.7 vs. 69.6%). However, in our study, 21.3% of our subjects had undergone surgical treatment for FMD with histopathologic confirmation, in contrast to 3.3% in the U.S. registry. A higher proportion of our cohort had experienced experienced a cerebrovascular event (48.9%) as compared to the U.S. registry, which noted TIA in 8.7% and stroke in 6.9% of its participants. This may reflect an ascertainment bias for patients who are more severely affected in being motivated to undertake the travel requirements for participation at the NIH. Our cohort did not include any individuals with asymptomatic disease discovered incidentally, whereas the U.S. registry included 5.6% with no symptoms or signs. In our study, surveillance MRA imaging of the entire arterial tree showed that 53.2% of our study subjects had vascular disease (aneurysm, beading, stenosis, or dissection) involving more than or equal to 2 arterial beds. Multiple vascular bed involvement was noted in 26.0–35.3% of patients with FMD in the U.S. registry who had imaging performed on additional arterial territories as clinically necessitated. Several caveats to the interpretation of our study MRA findings include that motion artifact from breathing is generally problematic for abdominal studies, previously treated arterial beds in cases of prior surgery or stent implantation could not be assessed, and we were unable to study every subject in the cohort because of contraindications to MR and/or gadolinium contrast administration. These caveats may have led to underestimating the severity and burden of systemic disease. Brain MR imaging is less susceptible to motion artifact, and we found that 12.8% of subjects had an intracerebral aneurysm. In the U.S. registry, 9 of 76 (11.8%) individuals with imaging data had a cerebral artery aneurysm, and 16 of 76 (21.1%) had carotid artery aneurysm, including both extracranial and intracranial internal carotid artery. Overall, the close alignment of demographic variables in our study as compared to the U.S. registry indicates that our cohort is a representative sample of U.S. patients with FMD, but likely with more severe clinical disease...
These findings have potential clinical implications. Our data suggest that an evaluation of degenerative spine arthritis and bone density may be helpful in identifying the cause and possible therapies for musculoskeletal symptoms. The yield of genetic testing for currently known connective tissue dysplasias in the FMD population is low in the absence of features that would otherwise indicate specific genetic testing, consistent with another published study (21). Given the rapid evolution of our understanding of vascular genetic diseases, formal genetic evaluation of patients with connective tissue features may be helpful to rule out other potentially overlapping disorders where FMD can be seen, such as vascular or type IV EDS. Finally, anecdotal evidence supports the rationale for therapy for FMD with pharmacologic agents that are known to decrease vascular TGF-B expression; (48) however, it is premature to make this treatment recommendation without a clinical trial. Further studies to identify the underlying molecular defect in FMD will be needed to clarify these issues."
The full text of this article is available for purchase from The FASEB Journal.
