Evaluation of a dermatoglyphic index to detect placental type variation in MZ twins

A dermatoglyphic index, which was previously used retrospectively to assess relationships between placental type in MZ twins with other variables, was tested for verification in two new separate samples of twins of known placental type. In both a French twin sample (19 monochorionic and 24 dichorionic) and the U.S. twin sample (49 monochorionic and 22 dichorionic), dermatoglyphic index scores were higher in monochorionic than dichorionic pairs. The difference in scores attained statistical significance when the two new samples were pooled. It is concluded that although the index cannot be used retrospectively to classify an individual MZ twin pair, an association of the placental type dermatoglyphic score with another variable in a group of MZ twins without any placentation information provides support for continuing to investigate prenatal effects on the associated variable. Am. J. Hum. Biol. 9:609-615, 1997. © 1997 Wiley-Liss, Inc.