Objective: To analyze the clinical and genetic features of patients with mitochondrial pyruvate carrier deficiency (MPYCD). Methods: This was a case series research. The clinical data, genetic characteristics, and glutamine treatment efficacy of 3 patients diagnosed with MPYCD at the Department of Neurology, Beijing Children's Hospital, Capital Medical University and Department of Pediatrics, Guizhou Provincial People's Hospital, from August 2019 to June 2023 were retrospectively collected. A literature search with "MPC1 gene" "MPC2 gene and" "mitochondrial pyruvate carrier deficiency" as keywords was conducted at the Wanfang Data Knowledge Service Platform, China National Knowledge Infrastructure (CNKI) and PubMed (up to June 2023). Clinical and genetic characteristics of patients with MPYCD were summarized. Results: Case 1 was a 3 years and 11 months old boy, while case 2 was a 4 years and 10 months old boy and case 3 was an 8 years and 9 months old girl. Case 2 and case 3 were siblings from one consanguineous family. All 3 patients presented with general developmental delay, growth failure and elevated serum lactate. Cranial magnetic resonance imaging (MRI) showed subtle bilateral symmetrical T2 signal hyperintensity in basal ganglia and thalamus in case 1, but normal in case 2 and 3. Trio-WES revealed case 1 harboring compound heterozygous missense variants c.208G>A (p.Ala70Thr) and c.290G>A (p.Arg97Gln) in MPC1 gene, while case 2 and 3 revealed a homozygous variant c.290G>A (p.Arg97Gln) in the same gene. All 3 cases were diagnosecl as MPYCD. Clinical symptoms including motor ability, cognition and activity endurance were improved in these 3 patients after taking glutamine for 2 years. A total of 5 articles published in English were reviewed, and no Chinese literature was found. Including these 3 cases, 15 cases were enrolled for analysis. Eleven patients carried MPC1 gene variants and 4 cases carried MPC2 gene variants. Except for 3 cases died during prenatal period, 9 of 12 enrolled born cases were onset before 6 months old. The most common clinical symptoms were mental and motor general developmental delay, microcephaly, growth failure and hypotonia. All patients had elevated blood lactate and pyruvate, but the ratio of lactate/pyruvate was normal. Seven patients performed cranial MRI, 3 exhibited non-specific changes, 2 showed bilateral symmetrical T2 signal hyperintensity in basal ganglia and thalamus, and 3 were normal. A total of 5 MPC1 gene missense variants and 2 MPC2 gene variants were identified in 15 cases. Conclusions: Onset age of patients with MPYCD is usually within 6 months. The main clinical characteristics are developmental delay, microcephaly and growth failure, accompanied by increased serum lactate and pyruvate. Glutamine supplement could lead to clinical improvements.
目的： 总结线粒体丙酮酸载体缺陷症（MPYCD）的临床和遗传特征。 方法： 病例系列研究。总结2019年8月至2023年6月首都医科大学附属北京儿童医院神经内科和贵州省人民医院儿科诊治的3例MPYCD患儿的临床资料、遗传学特征及谷氨酰胺治疗效果。分别以“MPC1”“MPC2”“线粒体丙酮酸载体缺陷症”“mitochondrial pyruvate carrier deficiency”为关键词对万方数据库、中国知网及PubMed数据库建库至2023年6月的文献进行检索，总结MPYCD的临床和遗传学特征。 结果： 例1，男，3岁11月龄；例2（男，4岁10月龄）和例3（女，8岁9月龄）为同胞姐弟。3例患儿均表现为智力及运动发育落后、生长受限和血乳酸升高。例1头颅磁共振成像（MRI）示双侧对称性基底节区、丘脑T2稍长信号，例2和例3头颅MRI正常。基因检测提示MPC1基因变异，例1为c.208G>A（p.Ala70Thr）和c.290G>A（p.Arg97Gln）复合杂合变异。例2和例3均为c.290G>A（p.Arg97Gln）纯合变异。3例均诊断为MPYCD。谷氨酰胺治疗2年，3例患儿的运动、认知和活动耐力有不同程度改善。检索符合条件的中文文献0篇，英文文献5篇，包括本组3例共有15例MPYCD患者（11例MPC1基因变异、4例MPC2基因变异）。除外3例胎儿期死亡，总结12例患儿的临床特点，9例在6月龄内起病。常见的临床表现是智力和运动全面落后（12例）、小头畸形（7例）、生长受限（6例）和肌张力减低（6例）。所有患儿均有血乳酸和丙酮酸升高，但乳酸/丙酮酸正常。7例患儿有头颅MRI资料，其中3例有脑萎缩、脑室扩张等改变，2例有双侧对称性基底节、丘脑异常信号，3例正常。共发现5个MPC1基因变异位点和2个MPC2基因变异位点，包括6个错义变异，1个核苷酸改变导致起始密码子改变。 结论： MPYCD患者多在6月龄内起病，主要表现为全面发育落后、小头畸形和生长受限，伴高乳酸和高丙酮酸血症，谷氨酰胺可在一定程度上改善症状。.