The Genetics Journal Club for this month features the article Molecular Support for Heterogonesis Resulting in Sesquizygotic Twinning that was recently published in the New England Journal of Medicine. The article describes boy-girl twins whose maternal DNA was identical, and who share paternal DNA as with genetic siblings. The authors propose that sesquizygosis is a newly identified and rare third type of twinning along with monozygotic (identical) and dizygotic (fraternal) twins . The article describes the authors’ research to identify other pairs of sesquizygotic twins, a case report regarding this set of twins who are now four years old, and theories regarding how sesquizygosis occurs.
Image citation: Anonymous (1922). Single ovum twins [online image] from Plass, E.D. (1922). Obstetrics for nurses. New York: Appleton and Company.