Screening Of Pathogenic Genes In Children With Congenital Hypothyroidism With Thyroid Hypoplasia

Objective To study the features of PAX8 and HHEX mutations and genetic characteristics in children with thyroid agenesis(TD), in order to provide evidence for gene diagnosis and gene treatment of Congenital hypothyroidism(CH).Methods Blood samples were collected from 63 TD patients in Shandong Province,China, and genomic DNA was extracted from peripheral blood leukocytes. Exon 3~4 of PAX8 were analyzed by PCR and direct sequencing. Meantime, screen HHEX gene of234 TD children using the same methods.Results Direct sequencing of PAX8 revealed a heterozygous missense mutation(c.155G/C, p.Arg52Pro) in one child with agenesis. Genetic screening of the child’s family revealed that the clinically unaffected parents do not carry the mutation,suggesting that the identified sequence change is a de novo mutation. Sequence analysis of HHEX did not show any non-synonymous variance in the coding regions, however, we found a SNP(IVS2+127 G/T, 5.13%) in the intron 2. Statistical analysis of the data was performed with SPSS 17.0 software package. Moreover, the difference in the allelic frequency between patients and MAF minor allele count was not significant(p>0.05).Conclusions De novo mutations can well explain TD for the characteristics of sporadic,providing a new theory basis for the pathogenesis of TD, PAX8 mutation rate is very low in TD patients in China and de novo PAX8 mutations are associated with thyroid dysplasia. Meantime our results indicated that the rate of HHEX mutation is very low,and may not serve as the main causative factor in Chinese TD patients.