Prenatal alcohol exposure alters the patterns of facial asymmetry

Abstract

Directional asymmetry, the systematic differences between the left and right body sides, is widespread in human populations. Changes in directional asymmetry are associated with various disorders that affect craniofacial development. Because facial dysmorphology is a key criterion for diagnosing fetal alcohol syndrome (FAS), the question arises whether in-utero alcohol exposure alters directional asymmetry in the face. Data on the relative position of 17 morphological landmarks were obtained from facial scans of children who were classified as either FAS or control. Shape data obtained from the landmarks was analyzed with the methods of geometric morphometrics. Our analyses showed significant directional asymmetry of facial shape, consisting primarily of a shift of midline landmarks to the right and a displacement of the landmarks around the eyes to the left. The asymmetry of FAS and control groups differed significantly and average directional asymmetry was increased in those individuals exposed to alcohol in utero. These results suggest that the developmental consequences of fetal alcohol exposure affect a wide range of craniofacial features in addition to those generally recognized and used for diagnosis of FAS.

Facial asymmetry and genetic ancestry inLatinAmerican admixed populations

“…In this context, departures from ideal conditions during ontogeny (i.e., environmental or genetic stress) may reduce the "effi.ciency" of normal developmental processes and increase the levei of FA (Palmer and Strobeck 1 1986;Parsons, 1990;Clarke, 1993;Mf!Jller and Swaddle, 1997) andlor DA (Mclntyre and Mossey, 2002;Hennessy et al, 2004;Schaefer et al 1 2006;DeLeon 1 2007;Ercan et al 1 2008;Klingenberg et al, 2010b;Barrett et al, 2012;Claes et al, 2012). Associations between heterozygosity and FA have been reported in mammals and other species (Soulé, 1979;Biémont, 1983;Leary et al, 1984;Palmer and Strobeck, 1986;Mitton, 1993;Vf!Jllestad, 1999;Leamy et al, 2001), with some exceptions (Wooten and Smith, 1986;Patterson and Paton, 1990;Beacham, American Journal of Physical Anthropology 1991; Britten 1 1996; Gilligan et ai., 2000;Leamy et al, 2001).…”

“…In addition, DA has been reported in humans (Mcintyre and Mossey, 2002;Schaefer et al, 2006;DeLeon, 2007;Ercan et al, 2008;Klingenberg et al, 2010b), although it is considered a subtle phenomenon.…”

“…Facial asymmetries have been the focus of extensive research from several perspectivas, including the assessment of variation in facial asymmetries on healthy young adult subjects (Ercan et al, 2008), facial dysmorphologies produced by prenatal alcohol exposure (Klingenberg et al, 2010b), sexual dimorphism (Claes et al, 2012), the relationship among asymmetries and growth and development (Wilson and Manning, 1996;Ferrario et al, 2001;Djordjevic et al, 2013), and the evaluation of dental fl.uctuating asymmetry (FA) as an indicator of developmental stress on Neanderthals and anatomically modern populations (Barrett et al, 2012), among others. As a whole, this vast array of studies suggest that the interest of researchers about asymmetry is not only focused on its genetic basis, but also on the putative environmental effects that affect its expression and, obviously, on the way in which both effects interact during the development.…”

An innocent victim (fetal alcohol syndrome)

“…The overall symmetry and dental symmetry have likewise been affected 14 ; to such an extent that a publication on ''fluctuating'' odontometric asymmetry 15 suggested that it may be a marker for FAS, since the mother's alcoholism constitutes a disruptive agent in the odontogenesis at the stage at which the dental organs are still only soft tissue.…”

Quantification of Orofacial Phenotypes in <em>Xenopus</em>

“…Further, we present a simple way to assess both the medial and lateral planes of the face without requiring sophisticated three-dimensional imaging equipment used in current studies 13,19 .…”