Text Box: DIFFERENTIAL EXPRESSION OF CONOTRUNCAL DEFECTS RELATED GENES IN CHICK EMBRYOS Liu F, Chen SB, Gu XF, Jiang MH, Liu XQ Xinhua Hospital, Shanghai, China Objective: Conotruncal defects (CTD), is a common type of cyanotic congenital heart defects. There is a close relation between cardiac neural crest and cardiac conotruncal development. CTD might be produced by ablation of premigratory cardiac neural crest in chick embryos. The purpose of this study was to determine conotruncal defects related genes by way of discovering differentially expressed messages between cardiac neural crest ablated heart and normal heart during development. Methods: Experimental chick embryos were subjected to cardiac neural crest ablation using electric stimulation. Suppression subtractive hybridization (SSH) was used to discover messages decreased or no expressing in outflow tract tissues without cardiac neural crest cells. A subtractive library was constructed, and cDNA chip was used to identify significant difference, then sequencing was done. Results: A subtractive library containing 261 clones was constructed, 83 clones (31.8%) were identified to be significant differentially expressed by cDNA chip. 15 clones were sequenced, 7 kinds of cDNA fragments were identified. 1 was known as Gallus DEAD-box RNA helicase mRNA. Conclusion: There are many kinds of gene take part in the cardiac conotruncal development. It is suggested that there is a potential relation between DEAD-box helicase genes and pathogenesis of CTD. 2362