While the specific causes of<unk>  have not been fully identified, there are various environmental or genetic factors that have been associated with<unk> . So far, around 20% of overall CHD cases have been due to known causes such as genetic defects and teratogens which are various factors causing embryo development abnormalities or birth defects. However, the other 80% of cases have little known about their cause. Genetic factors linked to<unk>  include various gene mutations or deletions. Gene deletions associated with<unk>  include chromosome 22 deletion as well as DiGeorge syndrome. Specific genes associations with<unk>  include: * JAG1 codes for ligands within the Notch family of proteins and is highly expressed in the developing heart. Mutations of the JAG1 gene can lead to abnormal heart development associated with<unk> . * NKX2-5 codes for cardiac morphogenesis regulators to allow for proper heart development. Defects in this gene typically causes septal defects and has been associated with around 4% of all<unk>  cases. * ZFPM2 is another cardiac regulator involved in regulation of GATA4. Mutations of the ZFPM2 gene lead to reduced GATA production and have been seen in some<unk>  cases. * VEGF a well-known endothelial growth factor involved in the vascularization of the heart. Decreased VEGF expression has been shown to be a modifier of<unk> . * NOTCH1 is involved in the vascularization of tissues and is the most common site of genetic variations involved with<unk> , accounting for 7% of all<unk>  cases. * TBX1 expresses progenitors involved with the development of the right ventricle. Chromosome 22q11 deletions also deleting TBX1 gene have been seen in 17%<unk>  cases. * FLT4 gene expression leads to Vascular endothelial growth factor receptor 3 (VEGFR-3) which helps vascularization. Mutations of this gene have been associated with<unk> , accounting for 2.4% of all cases. * FOXC2 is another gene involved in embryonic development of the cardiac system. Mutations of this gene have been shown to result in dysfunctional lymphatic syndrome and<unk> . * GATA4 aids in cardiac development by helping increase the production of cardiomyocytes. Mutations of this gene have been seen in various familial<unk>  cases often lasting 2-3 generations. *FLNA is a protein coded by the gene of the same name that crosslinks actin filaments into networks in cytoplasm and helps anchor membrane proteins for the actin cytoskeleton. Mutations of this gene were seen to cause<unk>  in some patients. The Environmental Factors that have been studied to potentially be associated<unk>  include: * Maternal Alcohol consumption: During embryonic development, many of the body’s processing and filtration systems are not fully developed. Fetal body is unable to process alcohol as well as adults which can lead to improper development, including cardiogenesis. While no conclusive evidence has been found between effects of alcohol consumption and<unk> , maternal alcohol consumption has been seen in various patients with<unk> . *Maternal smoking: Maternal smoking has been associated with various fetal complications such as premature delivery and low birth weight which can lead to<unk> . In the famous Baltimore-Washington Study, it was reported that smoking more than one pack per day while pregnant was associated with two specific cardiac deflects, both part of<unk> : pulmonary stenosis and transposition with VSD. *Maternal diabetes: Maternal diabetes, diabetes Mellitus, and gestational diabetes are well-known risk factors of fetal CHD, including<unk> . Maternal diabetes has been shown to increase the risk of cardiovascular deformations, namely the transposition of great arteries, one of the four deformations in<unk> . Studies have also looked at whether diabetes increases the risk of malformation or poor sugar regulation and have found that sugar regulation does not significantly affect cardiac malformations. Retrospective studies have shown that diabetic mothers with good glucose control still retained the elevated CHD risk. *Rubella: Rubella is characterized as mild, contagious viral disease with often unnoticed consequences. Infection with rubella during the first trimester has been seen to cause various fetal malformations, including<unk> . *Maternal Age: Older maternal age, especially after 35 can have various pregnancy risks due to existing co-morbidities such as hypertension, diabetes, hypothyroidism, and consanguinity. These risk factors can effect fetal development and lead to various fetal conditions such as CHD (including<unk> , Down Syndrome and Autism. Embryology studies show that anterior malalignment of the aorticopulmonary septum results in the clinical combination of a ventricular septal defect (VSD), pulmonary stenosis, and an overriding aorta. Right ventricular hypertrophy develops progressively from resistance to blood flow through the right ventricular outflow tract.
Tetralogy of Fallot
Cœur en sabot
Trilogy of Fallot
Double aortic arch
Transposition of the great vessels
Levo-Transposition of the great arteries
Dextro-Transposition of the great arteries
Persistent truncus arteriosus