We report the case of a 13-year-old female patient presenting with presyncope and palpitations. Her electrocardiogram revealed an abbreviation of the rate-corrected QT interval with imaging showing significant left ventricular dysfunction. Carnitine levels were measured as part of her diagnostic workup, discovering a rare, reversible cause of short QT syndrome (SQTS) and associated cardiomyopathy—primary carnitine deficiency (PCD) caused by a homozygous mutation in the SLC22A5 gene, leading to an in-frame deletion mutation (NP_003051.1:p.Phe23del) affecting the organic cation transporter 2 (OCTN2) protein. Following the treatment with oral carnitine supplementation, her QT interval returned to within the normal range with significant improvement in left ventricular function.

中文翻译：

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原发性肉碱缺乏所致左心室致密化不全心肌病和短 QT 综合征

我们报告一例 13 岁女性患者，出现先兆晕厥和心悸。她的心电图显示心率校正 QT 间期的缩写，影像显示明显的左心室功能障碍。作为诊断检查的一部分，测量了肉碱水平，发现了短 QT 综合征 (SQTS) 和相关心肌病的罕见、可逆原因——原发性肉碱缺乏症 (PCD)，由SLC22A5基因纯合突变引起，导致框内影响有机阳离子转运蛋白 2 (OCTN2) 蛋白的缺失突变 (NP_003051.1:p.Phe23del)。口服肉碱补充剂治疗后，她的 QT 间期恢复到正常范围，左心室功能显着改善。