In Japan, carnitine palmitoyltransferase II (CPTII) deficiency has been included as one of the primary target diseases in the expanded newborn mass screening program since 2018. However, many cases of the severe infantile hepatocardiomuscular form of CPTII deficiency showed severe neurodevelopmental delay or sudden death, which indicated that management of CPTII deficiency in the acute phase remains to be studied in detail. Herein, we discuss two cases diagnosed by newborn mass screening. Patient 1 was under strict clinical management from the neonatal period, with >20 admissions in 14 months, while Patient 2 was managed using a relatively relaxed approach, with only 2 admissions in the same period. Patient 1 showed normal development; however, Patient 2 expired at the age of 1 year 2 months. To develop strategies for preventing sudden deaths in patients with CPTII deficiency, this retrospective study focused on detailed clinical management practices and biochemical findings during the acute phase. We also investigated the correlation between conventional biomarkers (such as creatine kinase) and long-chain acylcarnitines. We propose that strict monitoring and immediate medical attention, even in case of slight fever or minor abdominal symptoms, can help prevent sudden death in patients with CPTII deficiency. Considering the higher morbidity rate of such patients, strict and acute management of CPTII deficiency cannot be overemphasized.

在日本，自2018年以来，肉碱棕榈酰转移酶II（CPTII）缺乏症已作为扩大的新生儿大规模筛查计划的主要目标疾病之一。但是，许多严重的婴儿肝心动型CPTII缺乏症病例表现出严重的神经发育延迟或猝死，这表明急性期CPTII缺乏症的治疗仍有待详细研究。本文中，我们讨论了由新生儿大规模筛查诊断出的两例病例。从新生儿期开始，对患者1进行严格的临床管理，在14个月内入院> 20，而对患者2进行相对宽松的治疗，同期仅入院2次。患者1显示正常发育；但是，患者2于1年2个月时死亡。为了制定预防CPTII缺乏症患者猝死的策略，这项回顾性研究的重点是急性期的详细临床管理实践和生化发现。我们还研究了常规生物标志物（例如肌酸激酶）与长链酰基肉碱之间的相关性。我们建议，即使在轻微发烧或轻微腹部症状的情况下，严格监控和立即就医也可以帮助防止CPTII缺乏症患者突然死亡。考虑到此类患者的发病率较高，因此不能过分强调CPTII缺乏症的严格和急性治疗。我们还研究了常规生物标志物（例如肌酸激酶）与长链酰基肉碱之间的相关性。我们建议即使在轻微发烧或轻微腹部症状的情况下，进行严格的监视和立即就医也可以帮助防止CPTII缺乏症患者突然死亡。考虑到此类患者的发病率较高，因此不能过分强调CPTII缺乏症的严格和急性治疗。我们还研究了常规生物标志物（例如肌酸激酶）与长链酰基肉碱之间的相关性。我们建议即使在轻微发烧或轻微腹部症状的情况下，进行严格的监视和即时医疗护理，也有助于防止CPTII缺乏症患者突然死亡。考虑到此类患者的发病率较高，因此不能过分强调CPTII缺乏症的严格和急性治疗。