Objective: To investigate the clinical features and genetic features of combined oxidative phosphorylation deficiency 32 (COXPD32) caused by MRPS34 gene variation. Methods: The clinical data and genetic test of a child with COXPD32 hospitalized in the Department of Neurology, Children\'s Hospital, Capital Institute of Pediatrics in March 2021 were extracted and analyzed. A literature search was implemented using Wanfang, China biology medicine disc, China national knowledge infrastructure, ClinVar, human gene mutation database (HGMD) and Pubmed databases with the key words \"MRPS34\" \"MRPS34 gene\" and \"combined oxidative phosphorylation deficiency 32\" (up to February 2023). Clinical and genetic features of COXPD32 were summarized. Results: A boy aged 1 year and 9 months was admitted due to developmental delay. He showed mental and motor retardation, and was below the 3rd percentile for height, weight, and head circumference of children of the same age and gender. He had poor eye contact, esotropia, flat nasal bridge, limbs hypotonia, holding instability and tremors. In addition, Grade Ⅲ/6 systolic murmur were heard at left sternal border. Arterial blood gases suggested that severe metabolic acidosis with lactic acidosis. Brain magnetic resonance imaging (MRI) showed multiple symmetrical abnormal signals in the bilateral thalamus, midbrain, pons and medulla oblongata. Echocardiography showed atrial septal defect. Genetic testing identified the patient as a compound heterozygous variation of MRPS34 gene, c.580C>T (p.Gln194Ter) and c.94C>T (p.Gln32Ter), with c.580C>T being the first report and a diagnosis of COXPD32. His parents carried a heterozygous variant, respectively. The child improved after treatment with energy support, acidosis correction, and \"cocktail\" therapy (vitaminB1, vitaminB2, vitaminB6, vitaminC and coenzyme Q10). A total of 8 cases with COXPD32 were collected through 2 English literature reviews and this study. Among the 8 patients, 7 cases had onset during infancy and 1 was unknown, all had developmental delay or regression, 7 cases had feeding difficulty or dysphagia, followed by dystonia, lactic acidosis, ocular symptoms, microcephaly, constipation and dysmorphic facies(mild coarsening of facial features, small forehead, anterior hairline extending onto forehead,high and narrow palate, thick gums, short columella, and synophrys), 2 cases died of respiratory and circulatory failure, and 6 were still alive at the time of reporting, with an age range of 2 to 34 years. Blood and (or) cerebrospinal fluid lactate were elevated in all 8 patients. MRI in 7 cases manifested symmetrical abnormal signals in the brainstem, thalamus, and (or) basal ganglia. Urine organic acid test were all normal but 1 patient had alanine elevation. Five patients underwent respiratory chain enzyme activity testing, and all had varying degrees of enzyme activity reduction. Six variants were identified, 6 patients were homozygous variants, with c.322-10G>A was present in 4 patients from 2 families and 2 compound heterozygous variants. Conclusions: The clinical phenotype of COXPD32 is highly heterogenous and the severity of the disease varies from development delay, feeding difficulty, dystonia, high lactic acid, ocular symptoms and reduced mitochondrial respiratory chain enzyme activity in mild cases, which may survive into adulthood, to rapid death due to respiratory and circulatory failure in severe cases. COXPD32 needs to be considered in cases of unexplained acidosis, hyperlactatemia, feeding difficulties, development delay or regression, ocular symptoms, respiratory and circulatory failure, and symmetrical abnormal signals in the brainstem, thalamus, and (or) basal ganglia, and genetic testing can clarify the diagnosis.
目的: 总结MRPS34基因变异致联合氧化磷酸化缺陷症32型(COXPD32)的临床表型及基因型特点。 方法: 回顾性分析2021年3月首都儿科研究所附属儿童医院收治的1例MRPS34基因变异致COXPD32患儿的临床资料及遗传学检测结果,并以“联合氧化磷酸化缺陷症32型”“MRPS34基因”或“combined oxidative phosphorylation deficiency 32”“MRPS34 gene”为关键词分别检索中国知网、万方和中国生物医学文献数据库或ClinVar、人类基因组突变数据库(HGMD)和PubMed数据库建库至2023年2月的文献。总结COXPD32的临床表型及基因型特点。 结果: 患儿,男,1岁9月龄,因“发育迟滞”入院。患儿语言及运动发育落后,眼神接触差,身高、体重及头围均低于同年龄同性别儿童P3。双眼内斜视,鼻梁低平,胸骨左缘闻及Ⅲ/6级收缩期杂音,四肢肌张力减低,持物不稳,存在意向性及静止性震颤。血气分析示重度代谢性酸中毒并乳酸酸中毒;头颅磁共振成像示双侧丘脑、中脑、脑桥及延髓多发对称性异常信号;心脏多普勒超声示房间隔缺损;基因检测示MRPS34基因c.580C>T(p.Gln194Ter)和c.94C>T(p.Gln32Ter)复合杂合变异,分别遗传自其父母,c.580C>T(p.Gln194Ter)为首次报道,诊断为COXPD32。予保证能量、纠正酸中毒、左卡尼汀口服液改善能量代谢及维生素B1、维生素B2、维生素B6、维生素C、辅酶Q10“鸡尾酒”疗法等治疗后患儿病情好转。文献检索到中文文献0篇,英文文献2篇,结合本例共8例患者。7例患者婴儿期内起病,1例不详。8例患者均存在生长发育迟滞或倒退,7例有喂养困难或吞咽困难,其余症状为肌张力障碍、眼部症状、小头畸形、便秘及特殊面容(皮肤粗糙、前额小、发际线低至前额、眉毛粗重、上腭高窄呈“V”形、牙龈厚、鼻小柱短及连眉)等;2例死于呼吸循环衰竭,6例报道时仍存活,年龄范围为2~34岁。8例患者均有血和(或)脑脊液乳酸升高。7例头颅磁共振成像示双侧脑干、丘脑和(或)基底节等大脑深部灰质核团对称性异常信号;尿液有机酸检测仅1例有丙氨酸升高。5例患者行组织呼吸链酶活性检测,均有不同程度的酶活性降低。检索到6个变异位点,6例为纯合变异,2例为复合杂合变异,其中c.322-10G>A在2个家系的4例患者中出现。 结论: MRPS34基因变异所致COXPD32临床表型多样,疾病严重程度轻重不一,轻者表现为生长发育迟缓、喂养困难、肌张力障碍、高乳酸、眼部症状及线粒体呼吸链酶活性降低等,或可存活至成年,重者可因呼吸循环衰竭致死。对于不明原因酸中毒、高乳酸血症、喂养困难、生长发育迟滞或倒退、眼部症状、呼吸循环衰竭及脑干、丘脑和(或)基底节对称性异常信号者,需考虑COXPD32,基因检测可明确诊断。.