A very rare form of apparent congenital absence of the tibia is presented in which duplication of a distal limb ray, rather than deletion, was found. Previous report of an associated truncus arteriosus has not come to my attention. Spontaneous mutation or idiopathic teratogenesis is hypothesized in the absence of a known etiologic agent.
Pratt AD. Apparent Congenital Absence of the Tibia With Lethal Congenital Cardiac Disease. Am J Dis Child. 1971;122(5):452-454. doi:10.1001/archpedi.1971.02110050122021