Incidence of carnitine transporter OCTN2 deficiency in Japanese patients with idiopathic cardiomyopathy

原发性全身性肉毒碱缺乏症。(SCD)是一种罕见的先天性代谢性疾病，以进行性心肌病、肌无力和Reye样综合征为特征。SCD与肉毒碱转运体OCTN 2基因突变有关。据报道，在一些白人SCD患者中，心肌病是唯一的症状。据推测，SCD被忽视的特发性心肌病，虽然这种疾病也是已知的治疗与左旋肉碱管理。因此，我们调查了居住在秋田县的42名不相关的日本特发性心肌病患者（平均年龄：58岁，年龄范围：13〜87岁）中肉毒碱转运蛋白缺陷的发生率。我们检查了血清和尿中的肉毒碱水平进行筛选，并确定了使用肉毒碱脱氢酶的酶循环法的值。然后，我们调查了知情同意的受试者中显示异常肉毒碱值的OCTN 2基因突变分析。血清总肉毒碱为67.2±16.6μM，血清游离肉毒碱为56.3±14.5μM，血清酰基肉毒碱为10.9±3.7μM，尿游离肉毒碱为90.3±150.4μmol/g肌酐，尿酰基肉毒碱为93.2±50.3μmol/g肌酐。虽然我们发现了一个人谁显示低于正常水平的肉毒碱，我们没有检测到OCTN 2基因突变。因此，我们在42例日本特发性心肌病患者中未发现SCD患者。我们认为，日本患者的肉毒碱转运蛋白缺乏症的发病率仅表现出心脏症状是相对较低的。

Primary systemic carnitine deficiency. (SCD) is a rare mborn metabolic disease characterized by progressive cardiomyopathy, muscle weakness, and Reye-like syndrome. SCD is responsible for themutations of carnitine transporter OCTN2 gene. It is reported that cardiomyopathy is only symptom in some Caucasian patients with SCD. It is supposed that SCD is overlooked as idiopathic cardiomyopahty although this disease is also known to be treatable with L-carnitine administration. Thus, we investigated the incidence of carnitine transporter deficiency in unrelated 42 Japanese patients with idiopathic cardiomyopathy who live in Akita prefecture (mean age: 58 years, range of age: 13〜87). We examined serum and urinary carnitne level for screening and determined the values by an enzymatic cycling method using carnitine dehydrogenase. Then, we investigated mutational analysis of OCTN2 gene in subjects with informed consent who showed abnormal carnitine values. The value (mean±SD) of tatal carnitine in serum is 67.2±16.6μM, free carnitine in serum was 56.3±14.5μM, acylcarnitine in serum was 10.9±3.7μM, free carnitine in urine was 90.3±150.4μmol/g Creatinine, and acylcarnitine in urine was 93.2±50.3μmol/g Creatinine. Although we found a subject who showed subnormal carnitine level, we detected no mutation in OCTN2 gene. Consequently, we found no patient with SCD in 42 Japanese patients with idiopathic cardiomyopathy. We suggested that the incidence of carnitine transporter deficiency in Japanese patients who showed only cardiac symptoms is relatively low.