摘要目的:探讨3例β-酮硫解酶缺乏症(BKTD)患儿的临床特征和基因变异。方法:回顾性分析河南省儿童医院2018年1月至2022年10月诊治的3例BKTD患儿的临床表现、实验室检查及基因检测资料，分析其临床和基因变异特点。结果:3例患儿均为男性，年龄为7 ～ 11个月，表现为外伤应激、感染后出现精神差、气促、呕吐、抽搐等，均存在重度代谢性酸中毒、血和尿中酮体升高、低血糖、血异戊烯酰肉碱和3-羟基异戊酰肉碱升高、尿2-甲基-3-羟基丁酸和甲基巴豆酰甘氨酸增多。基因检测提示患儿1的 ACAT1基因存在c.1183G>T杂合变异与1个涉及 ACAT1基因的大片段缺失(chr11：102980303_110501515)，患儿2的 ACAT1基因存在c.121-3C>G与c.826＋5_826＋9delGTGTT复合杂合变异，患儿3的 ACAT1基因存在c.928G>C与c.1142T>C复合杂合变异。患儿2与患儿3的4种变异均为已知的致病性或可能致病性变异。根据美国医学遗传学与基因组学学会变异相关指南，患儿1的c.1183G>T被评级为意义不明变异(PM2_Supporting＋PP3＋PP4)，11q22.3-11q23.1大片段缺失查询DGV正常人群拷贝数变异数据库未见收录，被评级为致病性拷贝数变异。 结论:ACAT1基因的变异考虑为3例BKTD患儿的遗传学病因。

abstractsObjective:To explore the clinical features and genetic variants in three children suspected for β-ketothiolase deficiency (BKTD).Methods:Clinical manifestations, laboratory examination and genetic testing of three children suspected for BKTD at Henan Children′s Hospital between January 2018 and October 2022 were collected, and their clinical and genetic variants were retrospectively analyzed.Results:The children were all males with a age from 7 to 11 months. Their clinical manifestations have included poor spirit, shortness of breath, vomiting, convulsions after traumatic stress and/or infection. All of them had severe metabolic acidosis, elevated ketone bodies in blood and urine, hypoglycemia, with increased isoprenyl-carnitine and 3-hydroxyisovalyl-carnitine in the blood, and 2-methyl-3-hydroxybutyrate and methylprotaroyl glycine in the urine. All of them were found to harbor compound heterozygous variants of the ACAT1 gene, including c. 1183G>T and a large fragment deletion (11q22.3-11q23.1) in child 1, c. 121-3C>G and c. 826+ 5_826+ 9delGTGTT in child 2, and c. 928G>C and c. 1142T>C in child 3. The variants harbored by children 2 and 3 were known to be pathogenic or likely pathogenic. The heterozygous c. 1183G>T variant in child 1 was unreported previously and rated as a variant of unknown significance (PM2_Supporting+ PP3+ PP4) based on guidelines from the American College of Medical Genetics and Genomics. The large segment deletion in 11q22.3-11q23.1 has not been included in the DGV Database and was rated as a pathogenic copy number variation. Conclusion:The variants of the ACAT1 gene probably underlay the pathogenesis of BKTD in these three children.