title: Situs Inversus Totalis in Twins: A Brief Review and a Life History / Twin Research: Twin Studies of Trisomy 21; Monozygotic Twin Concordance for Bilateral Coronoid Hyperplasia; Prenatal Hormonal Effects in Mixed-Sex Non-Human Primate Litters; Insurance Mandates and Twinning After In Vitro Fertilization / News Reports: First Report of Identical Twin Puppies; Twins Sisters Turn 100; Remembering an Identical Twin Production Designer; New York City Marathon Quadruplets.
abstract: The presence of situs inversus totalis (full reversal of internal organs) in twins is briefly reviewed. Information gathered from 35-year-old monozygotic (MZ) female twin pair discordant for this condition is presented. This is followed by summaries of research on the frequency of trisomy 21 (Down syndrome) in twins, the first case of MZ twin concordance for bilateral coronoid hyperplasia, prenatal hormonal effects in mixed-sex non-human primate litters, and links between insurance mandates and twinning following in vitro fertilization. The final section of this article describes twin-related events reported in the news, namely, the first recorded birth of identical twin puppies; the 100th birthday celebration of a pair of fraternal female twins, the passing of an award-winning identical twin production designer, and the first running of the New York City Marathon by a set of quadruplets.
authors.affiliation: Department of Psychology,California State University,Fullerton,CA,USA.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Segal
mesh_terms: D000818:Animals; D004200:Diseases in Twins; D005307:Fertilization in Vitro; D006801:Humans; D011323:Primates / Q000235:genetics / Q000502:physiology*; D012857:Situs Inversus / Q000235:genetics / Q000503:physiopathology*; D018433:Twin Studies as Topic / Q000639:trends*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic / Q000235:genetics