转录辅助调节因子HCFC1突变致罕见X连锁甲基丙二酸尿症CblX型一家系报告

目的探讨X连锁甲基丙二酸尿症CblX家系的临床及基因特点。方法回顾性分析1例经血液及尿液分析发现甲基丙二酸尿症,并采用靶向捕获二代测序进行HCFC1基因分析诊断的X连锁甲基丙二酸尿症患儿的临床资料。结果患儿,男,于2月龄时出现抽搐,智力运动障碍,5月龄时表现癫痫、重度发育落后,尿甲基丙二酸、血液丙酰肉碱增高,血浆总同型半胱氨酸增高,符合甲基丙二酸尿症合并同型半胱氨酸血症。甲基丙二酸尿症相关常染色体基因分析未见突变,X染色体转录辅助调节因子HCFC1第3外显子存在c.344C??T(p.Ala115Val)半合子突变,证实为CblX型甲基丙二酸尿症。患儿父母健康,曾有一子生后重度智力、运动障碍,合并难治性癫痫,于6月龄夭折。患儿母亲携带相同的突变,尿液可检出少量甲基丙二酸,血浆同型半胱氨酸轻度增高。患儿父亲未携带突变。结论以新一代测序技术首次确诊我国1例X连锁CblX型甲基丙二酸尿症家系。

A pedigree of a rare Cb1X type X-linked methylmalonic acidemia due to transcriptional co-regulator HCFC1 ;mutation

Objective To explore the clinical and genetic features in the pedigree of Cb1X type X-linked methylmalonic aciduria. Methods Clinical data of one child with X-linked methylmalonic aciduria diagnosed by blood and urine analysis were analyzed retrospectively. Targeted next-generation sequencing has been performed to detect the mutation of methylmalonic aciduria-related genes. Results The boy started presenting with seizures and severe mental retardation at 2 months of age. At 5 months of age, he had the manifestations of seizures, severe mental retardation, increased methylmalonic acid in urinary, increased propionylcarnitine in blood and increased plasma homocysteine, and met the requirements for the diagnosis of methylmalonic aciduria complicated with hyperhomocysteinemia. No mutation was detected in his MMA-related autosomal genes. However, a hemizygote mutation c.344C?>?T (p.Ala115Val) was identiifed in exon 3 of HCFC1 in X chromosome, which conifrmed the CblX type methylmalonic aciduria. His parents were healthy. His elder brother also manifested severe psychomotor retardation with intractable epilepsy, and died at 6 months of age with unknown cause. His mother carried the same mutation and had slightly elevated urine methylmalonic acid and plasma total homocysteine. His father did not carry the mutation. Conclusion A pedigree of a rare Cb1X type X-linked methylmalonic acidemia is ifrstly diagnosed in China by the new generation sequencing technology.