Beta 2-microglobulin: case report of a rare cause of cardiac amyloidosis
Abstract
Abstract Background Cardiac amyloidosis is caused by the deposition of misfolded proteins in the myocardium. The majority of cases of cardiac amyloidosis is caused by misfolded transthyretin or light chain proteins. In this case report, we discuss a case of a rare form of cardiac amyloidosis related to beta 2-microglobulin (B2M) in a patient not on dialysis. Case summary A 63-year-old man was referred for workup of possible cardiac amyloidosis. Serum and urine immunofixation electrophoresis demonstrated no monoclonal bands, and the serum kappa/lambda light chain ratio was normal, excluding light chain amyloidosis. Bone scintigraphy imaging showed diffuse radiotracer uptake in the myocardium, and genetic testing of the Transthyretin gene was negative for variants. This workup was consistent with wild-type transthyretin cardiac amyloidosis. The patient, however, later underwent endomyocardial biopsy due to factors inconsistent with this diagnosis, including a young age of presentation and a strong family history of cardiac amyloidosis despite no variants in the Transthyretin gene. This showed B2M-type amyloidosis, and genetic testing of the B2M gene showed a heterozygous Pro32Leu (p. P52L) mutation. The patient underwent heart transplantation with normal graft function 2 years post transplant. Discussion While contemporary advancements allow for the non-invasive diagnosis of transthyretin cardiac amyloidosis with positive bone scintigraphy and negative monoclonal protein…
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Evidence Hub reads this as a case report, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health.
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