Dysferlinopathy misdiagnosed as Polymyositis
Some types of limb-girdle muscular dystrophy (LGMD), as well as facioscapulohumeral muscular dystrophy (FSHD) are sometimes misidentified as autoimmune diseases because their clinical and laboratory presentations are similar. Of the various limb-girdle muscular dystrophies, dysferlinopathy is particularly prone to misdiagnosis as polymyositis. Because the inheritance pattern for dysferlin deficiency is recessive, you may have this form of LGMD even if it is not present in your immediate family. It is estimated that around 25% of patients suffering from dysferlinopathy are misdiagnosed with polymyositis. Please read the above patient stories. Muscular dystrophy can mimic inflammatory myopathies, leading to misdiagnosis and ineffective treatments, but there are new tools that help provide an accurate diagnosis. It’s important to pursue the correct diagnosis to avoid the side effects of ineffective treatment which can include non-recoverable loss of strength.
Therefore, a diagnosis of muscular dystrophy (likely dysferlinopathy) should be considered if a patient shows atypical polymyositis presentations such as the following:
- No arthritis, fevers, lung disease, cardiac abnormalities or swallowing problems
- No detectable autoantibodies
- No response to immunosuppressive therapy
The Jain Foundation is committed to helping patients or physicians who have questions regarding a possible misdiagnosis. The Jain Foundation is privately funded and does not ask for funds from patients or physicians. If you are a patient, you can apply for free genetic sequencing sponsored by a consortium of LGMD Family Foundations. The ultimate goal is for everyone to obtain an accurate diagnosis which will lead to the most effective forms of treatment. If you want to learn more about Polymyositis, please visit The Myositis Association at: www.myositis.org