Genetics Research Of 16 Candidate Pathogenic Genes In Children With Congenital Hypothyroidism

Objective: To investigate the types and characteristics of gene mutations in children with congenital hypothyroidism(CH),we analyze the frequency and combination of gene mutations to explore the role of genetic factors in the pathogenesis of CH,which is helping for the early screening and diagnosis of CH.Methods: 377 sporadic CH children comprised by 288 thyroid dysgenesis(TD)and 89 gland-in-situ(GIS)were recruited for our study from newborn screening center from Shandong province.Thyroid morphologic preliminary classification by thyroid ultrasonography,further differentiation of unclassified adopted thyroid technetium labeled imaging.The exons of the 16 candidate genes from genome DNA were sequenced for the original sequencing data.The variant position,variant type,conservative prediction and other information are annotated by ANNOVAR through a variety of databases,such as 1000 Genome,GRCh37/hg19 and DbSNP.Comprehensive analysis of mutation sites was carried out by SIFT,Polyphen 2,Mutation Taster and CADD to predict the pathogenicity of mutation.Frequency analysis of the pathogenic mutations revealed a mutation spectrum for various clinical phenotypes and we analyzed the biallelic and multi-gene combined mutations.Results: 1.Pathogenicity variants were identified in 58.09% of CH patients(219/377)from 168 sites in all 16 candidate genes.2.DUOX2 was the most commonly pathogenic variation in our CH cohort(21.22%,80/377),but DUOXA2 in TD(18.75%,54/288)and DUOX2 in GIS(34.83%,31/89).Biallelic TSHR or DUOX2 mutations were found most common in TD,and biallelic DUOX2 was the most significant in GIS.We also found for the first time that biallelic TG,DUOXA2 and DUOXA1 mutations may participate in the pathogenesis of TD in our study.In addition,triallelic mutations in DUOX2 were found in 1.04% TD(3/288)and 3.37%(3/89)GIS.3.Among the 61 CH cases carried digenic mutations,the most frequently bigenic mutation combination was DUOXA1 with DUOX2(29.51%,18/61).In 26 CH cases had trigenic mutations,the most common association was DUOX2 and TG combined with DUOXA1(15.38%,4/26)or DUOXA2(11.54%,3/26);and 7 subjects had joint mutated of four genes with various combinate mode.4.In our study,the c.C738G(p.Y246X)in DUOXA2(18.04%,68/377)was the most common mutation,and 157 novel mutations were identified distributing in all 16 candidate genes except DUOXA1.Conclusion: We carried out a large sample,multi-gene and multi-center genetic analysis of children with congenital hypothyroidism in Shandong Province,and drew a fine clinical phenotype gene mutation spectrum for this area.We analyzed the types and characteristics of pathogenic mutations identified from candidate genes in children with TD and GIS in Shandong province.Among the 16 candidate genes,we found that DUOX2 was the most commonly mutated pathogenic gene.Multiple-site or multiple-gene mutation in individual is a prominent feature in CH,which confirms that CH is a complex disease involving multiple genes.This study enriched the diversity of genetic spectrum of CH and laid a theoretical foundation for further clinical treatment and gene functional studies.