Study on Possible Increase in Twinning Rate at a Small Village in South Brazil

Abstract

A high frequency of twin births has been observed in Linha São Pedro, a small settlement which belongs to the city of Cândido Godói, located 524 km Northwest from Porto Alegre, Rio Grande do Sul, Brazil, in an ethnically homogeneous population of German descent restricted to a small geographic region. From 1990 to 1994, the proportion of twin births in Linha São Pedro was 10%, significantly higher than the 1.8% rate for the state of Rio Grande do Sul as a whole. Genealogical analysis showed a high recurrence of multiple births within families, as well as a high level of inbreeding in the community. Zygosity data indicated that 9 of the 17 pairs of twins studied (53%) were dizygotic. No external environmental factors were detected that could be influencing the appearance of this characteristic. This preliminary investigation confirmed the presumed existence of a high twinning rate in the community. The high familial recurrence and the high inbreeding rate suggests the presence of genetic twinning factors. Complementary studies of twins that have yet to be evaluated and the search for additional risk factors, as well as linkage studies, should contribute to a further understanding of the biological factors related to twin births in the human species.

Twinning and heteropaternity in chimpanzees (Pan troglodytes)

“…Relatively high levels of inbreeding possibly played a role in twinning at Yerkes (Eckhardt, 1988;Geissman, 1990). Although inbreeding alone cannot implicate a specific gene(s) to explain elevated twinning rates, numerous inbred human populations have elevated DZ and/or MZ twinning rates (Carmelli et al, 1981;Das Chaudhuri et al, 1993;Goswami, 1987;Matte et al, 1996;Mieckle et al, 1976). Genetic models and mechanisms have been proposed for MZ twinning (Harvey et al, 1977;Shapiro et al, 1978;Steinman, 2003).…”

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

“…The earliest available baptism records date from 1927, but complete and reliable data were available only from 1959 onwards. Since there is a suggestion that LSP may have an especially high twinning frequency [18], we used a chi-square test to assess whether LSP has a higher twinning rate as compared to the remaining CG districts (CG-LSP) considering 1959 to 2008. Because maternal age (MA) is a known factor affecting twinning [11] we compared MA distribution in LSP and CG-LSP using data obtained from interviews to test if women living in LSP have children later in life, thus increasing the chance of twin births.…”

“…However, twinning may not be equally distributed throughout the municipality. In 1994, the twinning birth rate in Linha São Pedro (LSP), a small district of CG was estimated as 10% [18]. CG and LSP were both founded at the beginning of the Twentieth Century by a few families of German ancestry coming from other German-founded towns in Rio Grande do Sul.…”

Kodinji village puzzles medical science

“…High twin birth rates have also been reported in other areas of the world: Igbo Ora (Nigeria) 5%; 3 Linha Sao Pedro (Brazil) 10%; 4 Heshan (China) 5%; 5 Mohammedpur Umri (India) 10%; 6 and Velikaya Kopanya (Ukraine) 3% 7 . The large numbers of twin births in secluded places is a mystery.…”