Zygosity Diagnosis: When Physicians and DNA Disagree/Twin Research: Sex-Discordant Chimeric Twins; Unrelated Bone Marrow Transplantation in Infant Twins With Congenital Amegakaryotic Thrombocytopenia; Twin Study of Attractiveness to Mosquitoes; Twins Coping With Crisis/Media Highlights: The Less Favored Twin; Paternity Issues; Twins With Late-Onset Tay-Sachs Disease; Triplets at MIT

Abstract

Physicians and other medical professionals do not always provide new parents with an accurate diagnosis of their twins’ zygosity. An overview of this problem is presented, supplemented by an interview with a mother who recently learned that her 2-year-old ‘dizygotic (DZ)’ twin girls are actually ‘monozygotic (MZ)’. Reviews of two case studies, one of twins with sex-discordance and chimerism and the other of twins with congenital amegakaryotic thrombocytopenia, follow. Two additional studies, one a twin analysis of attractiveness to mosquitoes and the other a study of twins coping with crisis, are also described. Several articles and letters from the popular media, concerning less favored twins, paternity issues surrounding superfecundation, twins with late-onset Tay-Sachs disease, and triplets admitted to MIT are informative and insightful.

Zygosity Misclassification of Recent Young Twins by Maternal Reports in Japan

“…Since the number of incorrect cases was only four out of 46 in the present study, no conclusive reason for these incorrect determinations could be found. In general, the misclassification of DZ as MZ occurred for several reasons, with fused placentation, in which two placentas seem to be one placenta at a glance, being one of them [15].…”

“…In particular, many MZ twins are misclassified as being DZ because they have two placentas [8][9][10][11][12][13][14][15][16]. In Japan, this problem has been pointed out previously [10].…”