AUTHOR=Wang Yilin , Wang Chunmei , Liu Meiyan , Xu Wuhen , Wang Simei , Yuan Fang , Luo Xiaona , Xu Quanmei , Yin Rongrong , Wang Anqi , Guo Miao , Lin Longlong , Wang Chao , Cheng Hongyi , Liu Zhiping , Zhang Yuanfeng , Zeng Fanyi , Yan Jingbin , Chen Yucai TITLE=Segawa syndrome caused by TH gene mutation and its mechanism JOURNAL=Frontiers in Genetics VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.1004307 DOI=10.3389/fgene.2022.1004307 ISSN=1664-8021 ABSTRACT=

Dopa-responsive dystonia (DRD), also known as Segawa syndrome, is a rare neurotransmitter disease. The decrease in dopamine caused by tyrosine hydroxylase (TH) gene mutation may lead to dystonia, tremor and severe encephalopathy in children. Although the disease caused by recessive genetic mutation of the tyrosine hydroxylase (TH) gene is rare, we found that the clinical manifestations of seven children with tyrosine hydroxylase gene mutations are similar to dopa-responsive dystonia. To explore the clinical manifestations and possible pathogenesis of the disease, we analyzed the clinical data of seven patients. Next-generation sequencing showed that the TH gene mutation in three children was a reported homozygous mutation (c.698G>A). At the same time, two new mutations of the TH gene were found in other children: c.316_317insCGT, and c.832G>A (p.Ala278Thr). We collected venous blood from four patients with Segawa syndrome and their parents for real-time quantitative polymerase chain reaction analysis of TH gene expression. We predicted the structure and function of proteins on the missense mutation iterative thread assembly refinement (I-TASSER) server and studied the conservation of protein mutation sites. Combined with molecular biology experiments and related literature analysis, the qPCR results of two patients showed that the expression of the TH gene was lower than that in 10 normal controls, and the expression of the TH gene of one mother was lower than the average expression level. We speculated that mutation in the TH gene may clinically manifest by affecting the production of dopamine and catecholamine downstream, which enriches the gene pool of Segawa syndrome. At the same time, the application of levodopa is helpful to the study, diagnosis and treatment of Segawa syndrome.