1.Studies On The Mutation And Expression Of TBX5 Gene In Human Simple Congenital Heart Disease 2.Analysis On SNPs In Susceptible Region 12q13 Of Simple Congenital Heart Disease

Congenital heart disease(CHD) is a common newborn defect,the morbidity of which is from 4% to 8%. The clinical data and epidemio-logical study indicate that the genetic factors play an important role in the pathogenesis of CHD,and the heritability is from 55% to 65%. So identifying genes involved in the cardiac development from the molecular level is very important to find out the mechanism of CHD and make a better therapeutic program. TBX5 is a transcription factor that play a critical role during the cardiac development. TBX5 gene was identified and cloned from Holt - Oram syndrome ( HOS) in 1997. HOS belong to autosomal dominant and the patients were characterized by congenital heart defects and upper limb abnormalities. Studies have proved that TBX5 gene mutations would lead to HOS. But it is still unknown whether some mutations and abnormal expression of T-BX5 gene may cause human simple congenital heart disease. We in-vestigated the mutation and expression of TBX5 gene in human simple congenital heart disease so as to clear whether the mutations and the abnormality in transcription level of TBX5 gene is a kind of mechanism causing human simple congenital heart disease.Methodswe designed primers of 8 exons of TBX5 gene and added a [ GC ] clamp to the upper primer 5' tip, then examined the mutations of coding sequence of TBX5 gene in 216 individuals from 61 CHD core pedigres by polymerase chain reaction - denaturing gradient gel electrophoresis (PCR - DGGE) ; Using (3 - actin as internal control , we detected the differential expression between 34 myocardium samples from simple congenital heart disease patients (including ASD, VSD and F4) and 3 normal controls by reverse transcription - polymerase chain reaction(RT - PCR) .ResultsNo mutations were detected in 8 exons of TBX5 gene in all samples by PCR - DGGE; The mRNA expression levels of TBX5 gene show descent tendency in samples of simple congenital heart disease compared with normal controls; There is no obvious difference between ASD, VSD and F4.ConclusionMutations in coding region of TBX5 gene may not cause humansimple congenital heart disease; The abnormality in transcription level of TBX5 gene may be a kind of mechanism causing human simple congenital heart disease.