Research work · 2006
Reply: Mosaic/chimeras and twinning in the current reproductive genetics perspective
Charles E. Boklage
Human Reproduction
Abstract
Sir, My thanks to Dr Golubovsky for his incisive questions and comments. It seems he pleads the case for the common knowledge that (i) there are two kinds of twins, (ii) we understand clear differences in the cellular and genetic origins thereof and (iii) we can use those differences with confidence as bases for productive genetic analyses. Thirty-five years ago I believed that too, and it occurred to me that we might learn about embryogenesis by studying developmental differences between monozygotic (MZ) twins (who must have experienced unusual embryogenesis and were supposed to be plagued by great excesses of embryogenic errors) and dizygotic (DZ) twins (who were thought to be doing embryogenesis quite normally and independently, just like singletons). Every result from those studies has shown that picture of DZ development to be wrong. The differences between MZ and DZ twins are of little interest compared with those between all twins and singletons. Measurable traces of embryogenic a/symmetries (and errors in establishing them) in twins and their first-degree relatives are clearly and consistently incompatible with the independent double-ovulation hypothesis of DZ twin origin.