Cyanotic congenital heart disease in one of identical twins: Report of two cases

1. 1. Two pairs of identical twins are reported. One twin of each pair had cyanotic congenital heart disease. The other twin was completely normal. One set of twins was girls and the other, boys. The affected twin had pentalogy in the first pair, tetralogy of Fallot in the second pair. They were 9 years of age at the time of the examination. The diagnosis of congenital heart disease was established by clinical findings and cardiac catheterization. 2. 2. No detectable genetic history or definite environmental factors could be established in either pair. 3. 3. The monozygoticity of the twins was based on the “similarity method” as well as serologic identity. 4. 4. The finger- and palmprints of these twins were not identical. Uselessness of the finger- and palmprints as a diagnostic test in distinguishing identical from nonidentical twins has been emphasized. 5. 5. The literature concerning congenital heart disease affecting only one of identical twins and the causes of congenital heart diseases have been reviewed. No definite explanation could be concluded for the congenital heart disease involving only one of the identical twins.