Objective: Atrioventricular septal defect (AVSD) is one form of major congenital cardiovascular malformations and CRELD1 is the first identified AVSD candidate gene. We hypothesize that CRELD1 was involved into the process of extracellular matrix production/deposition and valvuloseptal formation as a cell adhesion molecule. Mutations of the CRELDs might result in its functional changes and then affect the process of heart development.
Method: The genomic DNA of 66 children with AVSD were analyzed for the variation in the CRELD1 gene by sequencing. Western-blot and FQ RT-PCR was applied to examine the expression of CRELD1,Tenascin-C and Aggrecan of mutational gene.
Results: We found one missense mutation C857G (P286R) and one new polymorphisms T1136C(M379T). The P286R missense mutation of CRELD1 make the gene gain function. Compared with the un-load, the Aggrecan mRNA expression was down-regulation in wild-type and mutant-type (t value was 140.27 vs 26.36,P<0.01). However, the down-regulation was more significant in mutant-type than in wild-type(t=-25.69,P=0.002). There was no significant difference of the Tenascin-C expression between wild-type and the un-load(t=1.167, P>0.05), but the Tenascin-C expression was up-regulation in mutant-type (t=6.66, P=0.022).
Conclusion: Low prevalence of CRELD1 mutations and the normal phenotype with mutational gene indicated that AVSD is either a complex trait, influenced by both genetic and environmental susceptibility factors, or a monogenic trait caused by a few AVSD genes. The P286R mutation of CRELD1 downregulates the expression of Aggrecan and upregulates the expression of Tenascin-C,both of which are crucial extracellular matrix in the formation of the atrioventricular septal.