Twin Research and Human Genetics

Articles/Belgium

The East Flanders Prospective Twin Survey (EFPTS)

Catherine A. Deroma1 c1, Robert F. Vlietincka2, Evert W. Thierya3, Fernand O. G. Leroya4, Jean-Pierre Frynsa5 and Robert M. Deroma6

a1 Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium. catherine.derom@uz.kuleuven.ac.be

a2 Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium.

a3 Association for Scientific Research in Multiple Births, Ghent, Belgium.

a4 Association for Scientific Research in Multiple Births, Ghent, Belgium.

a5 Department of Human Genetics, Katholieke Universiteit Leuven, Leuven, Belgium.

a6 Association for Scientific Research in Multiple Births, Ghent, Belgium.

Abstract

The East Flanders Prospective Twin Survey (EFPTS) is a prospective, population-based registry of multiple births in the province of East Flanders, Belgium. EFPTS has several unique features: it is population based and prospective, with the possibility of long-term follow-up; the twins (and higher order multiple births) are ascertained at birth; basic perinatal data recorded; chorion type and zygosity established; and since 1969 placental biopsies have been taken and frozen at −20 °C for later determination of genetic markers. The EFPTS is the only large register that includes placental data and allows differentiation of 3 subtypes of monozygotic (MZ) twins based on the time of the initial zygotic division: the dichorionic–diamnionic pairs (early, before the 4th day after fertilization), the monochorionic–diamnionic pairs (intermediate, between the 4th and the 7th day post fertilization), and the monochorionic–monoamnionic pairs (late, after the 8-day post fertilization). This added a new dimension to didymology (the science of twins; didymos is the Greek word for twin): the timing of MZ twinning. Studies can be initiated taking into account primary biases, those originating in utero. Such studies could throw new light on the controversy over the validity of the classic twin method, the consequences of early embryological events (before and just after implantation of the embryo), the origin of congenital malformations, the sex proportion of multiples, the gene–environment interactions as far as intrauterine environment is concerned, to name but a few.

(Received July 08 2006)

(Accepted August 18 2006)

Correspondence:

c1 Address for correspondence: Dr C. Derom, Kwadenplasstraat 20, B-9070 Destelbergen, Belgium.

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