Nancy L. Segal Ph.D.


Twin Congress Highlights and Telling Twins Apart

News from the Budapest Twin Congress and Twins' Different DNA

Posted Jan 13, 2015

The 15th International Congress of Twin Studies took place in Budapest, Hungary in November 2014. This congress, held together with the 3rd Joint World Congress on Twin Pregnancy, occurs every two years. The year 2014 was a wonderful time to present the latest findings from the world of twin research. It was also a moment to honor the late Dr. Louis Keith, an acclaimed physician and twin researcher, who passed away on July 6, 2014. Dr. Keith is survived by his identical twin brother Donald.

There were many outstanding talks at this meeting. Initial introductions were presented by the identical twin doctors Adam and David Tárnoki, followed by the Deputy Mayor of Budapest, Dr. Gábor Bagdy. Lighter moments were provided by the identical twin singers, Lajos and Béla Barna. The Hungarian photographer Imre Benko displayed a wonderful book of twin photographs, Ikrek (Twins), 1982-2008, published by the Hungarian Museum of Photography (2009). The opening night concluded with a lecture, “Twins in History and Art,” by Professor Donatella Lippi, Professor of Medicine and History at the University of Florence, in Italy.

One of the more unique and captivating sessions was entitled “Twin Studies in Central and Eastern Europe.” This session covered Eastern European twin registries and festivals. In addition, Hungarian twin studies by Júlia Métinek and Andrew Czeizel have covered congenital abnormalities and psychosexual development. (Métinek published a marvelous 2008 book on conjoined twins, Egy vagy ketto? English: One or two?). There have also been some international research collaborations. Other topics were genetic influences on cardiac characteristics, twinship in sociological perspective and current plans for the establishment of a nation-wide twin registry in Hungary. 

Another popular event was the Bulmer symposium describing new developments in the biology of twinning. Topics included genetic influences on identical twinning, unusual placentation in a fraternal twin pair, the importance of helping parents understand concepts of zygosity (twin type) and chorionicity, the effects of assisted reproductive technology (ART) on twin placentation, hormonal levels of mothers of twins, twinning rates, and genetic counseling with twins. ICOMBO (International Council of Multiple Birth Organisations), whose mission is “to raise awareness of the unique needs of multiple-birth infants, children, adults and their families promoting their health, education and welfare,” meets regularly as part of the International Twin Congress, with a series of scheduled sessions.

The 16th International Congress of Twin Studies is scheduled to take place in Madrid, Spain in October 2017. However, a one day twin studies session will occur in conjunction with the annual meeting of the Behavior Genetics Association, to be held in Brisbane, Australia in June 2016. Attendance and participation is encouraged, not just by twin researchers, but by interested individuals from diverse disciplines. Twin research has something to offer everyone.

Telling Identical Twins Apart

Having an identical twin has many medical benefits, among them the availability of a perfect donor in the event of blood transfusion or organ transplantation. A related, but vexing, issue has been paternity, criminality, and other forensic situations involving twins. That is because the identity of the culprit could not be resolved since DNA at the crime scene matched two individuals, not one. Recently, German researchers Jacqueline Weber-Lehmann and colleagues devised a DNA test that can tell identical twins apart. The procedure will be used for the first time in a Boston rape case involving identical twins Dwayne and Dwight McNair, pending the judge’s approval.

The investigators developed a test based on the sequencing of the whole genome and the identification of unusual new mutations. The participants were an adult male identical twin pair and the wife and child of one of the twins. In order to avoid any biases, the laboratory team was not given information as to which twin was the child’s father. The twins’ zygosity and parent-child paternity were first confirmed by standard methods. Note that at this stage either of the twins could have been identified as the father. Then, DNA from the twins’ sperm sample and the child’s blood was used to identify inherited mutations that occurred after the twinning event took place. Such mutations would only be present in the father and child. Ultimately, five mutations were found in the father and his son, but not in the uncle (the father’s identical co-twin). 

Additional information about the International Twin Congress and the new DNA test will appear in a forthcoming issue of the journal Twin Research and Human Genetics, published by Cambridge Press.

About the Author

Nancy L. Segal, Ph.D., is a professor of psychology and the Director of the Twin Studies Center, at California State University, Fullerton.

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