Discordant abnormalities in monozygotic twins

Hypothesis: anencephaly and spina bifida are usually preventable by avoidance of a specific but unidentified substance present in certain potato tubers.

“…Further, since it is likely that even MZ twin embryos frequently differ in the rate of development, the timing of a daily teratogenic hazard might happen to catch one twin at a critical, sensitive stage of short duration and to miss the corresponding stage in the co-twin. The inference on difference in the rate of development is by extrapolation backwards from a frequent disparity noted by Fogel, Nitowsky, and Gruenwald (1965) and others in full-term birthweight. This disparity exceeds 20% three times more often in MZ than in DZ pairs.…”

Multiple Pregnancies

“…It has been the topic of numerous publications, e.g., Fogel et al ( 1965 ;Benirschke and Masliah 2001 ) . Machin ( 1996 ) has summarized all known or hypothesized facts and theories of such unusual cases.…”

Congenital tracheobronchial stenosis in monozygotic twins

“…One traditional explanation is that stochastic factors may have a role in the development of such discordant abnormalities in twins with genetically determined abnormalities [8]. This mechanism may possibly explain partly the dierences in tracheobronchial malformations of the twins we presented [1,8].…”