PDF(Pubmed)
Abstract：
UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: While contemporary advancements allow for the non-invasive diagnosis of transthyretin cardiac amyloidosis with positive bone scintigraphy and negative monoclonal protein screen, clinicians should be aware of rarer forms of amyloidosis where endomyocardial biopsy is required to make the diagnosis.
UNASSIGNED: 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.
UNASSIGNED: While contemporary advancements allow for the non-invasive diagnosis of transthyretin cardiac amyloidosis with positive bone scintigraphy and negative monoclonal protein screen, clinicians should be aware of rarer forms of amyloidosis where endomyocardial biopsy is required to make the diagnosis.
摘要：
■心脏淀粉样变性是由错误折叠的蛋白质在心肌中的沉积引起的。大多数心脏淀粉样变性病例是由错误折叠的甲状腺素运载蛋白或轻链蛋白引起的。在这个案例报告中,我们讨论了一例罕见的与β2-微球蛋白（B2M）相关的心脏淀粉样变性病例。
■一名63岁男子被转诊为可能的心脏淀粉样变性。血清和尿液免疫固定电泳显示没有单克隆条带，血清κ/λ轻链比值正常，不包括轻链淀粉样变性。骨闪烁显像显示心肌弥漫性放射性示踪剂摄取，并且对Tranthyretin基因的基因检测没有变异。此检查与野生型甲状腺素运载蛋白心脏淀粉样变性一致。病人,然而,由于与该诊断不一致的因素，后来接受了心内膜活检，包括年轻的表现年龄和强烈的心脏淀粉样变性家族史，尽管在转甲状腺素蛋白基因中没有变异。这表明B2M型淀粉样变性，和B2M基因的遗传测试显示杂合Pro32Leu（p。P52L）突变。移植后2年，患者接受了心脏移植，移植物功能正常。
■虽然当代的进步允许通过骨闪烁显像阳性和阴性单克隆蛋白筛查对甲状腺素运载蛋白心脏淀粉样变性进行非侵入性诊断，临床医生应注意较罕见的淀粉样变性，其中需要进行心内膜活检才能进行诊断。
■一名63岁男子被转诊为可能的心脏淀粉样变性。血清和尿液免疫固定电泳显示没有单克隆条带，血清κ/λ轻链比值正常，不包括轻链淀粉样变性。骨闪烁显像显示心肌弥漫性放射性示踪剂摄取，并且对Tranthyretin基因的基因检测没有变异。此检查与野生型甲状腺素运载蛋白心脏淀粉样变性一致。病人,然而,由于与该诊断不一致的因素，后来接受了心内膜活检，包括年轻的表现年龄和强烈的心脏淀粉样变性家族史，尽管在转甲状腺素蛋白基因中没有变异。这表明B2M型淀粉样变性，和B2M基因的遗传测试显示杂合Pro32Leu（p。P52L）突变。移植后2年，患者接受了心脏移植，移植物功能正常。
■虽然当代的进步允许通过骨闪烁显像阳性和阴性单克隆蛋白筛查对甲状腺素运载蛋白心脏淀粉样变性进行非侵入性诊断，临床医生应注意较罕见的淀粉样变性，其中需要进行心内膜活检才能进行诊断。
