This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to examine the frequency of specific beta-adrenergic receptor, G-protein, Alpha 2-adrenergic receptor, Erk2 and H-Ras single nucleotide polymorphisms (SNP's) in a sample of children with congenital heart disease, specifically hypoplastic left heart syndrome (HLHS) and d-transposition of the great arteries (dTGA). Specific SNP's will be correlated with post-operative inotropic requirements, measures of ventricular function, and mortality. Blood will be drawn or skin biopsies will be obtained (infants) from study patients for the purpose of DNA isolation and determination of SNP's of the above-stated genes.