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Amniotic fluid deficiency and congenital abnormalities both influence fluctuating asymmetry in developing limbs of human deceased fetuses.

ten Broek CM, Bots J, Varela-Lasheras I, Bugiani M, Galis F, Van Dongen S - PLoS ONE (2013)

Bottom Line: One aspect that has received relatively little attention in the literature is the consequence of direct mechanical effects on asymmetries.We discovered that both factors contributed significantly to the increase in FA.We, thus, conclude that correcting for the relevant direct factors allowed for a representative test of the association between DI and stress, and confirmed that fetuses form a suitable model system to increase our understanding in patterns of FA and symmetry development.

View Article: PubMed Central - PubMed

Affiliation: Group of Evolutionary Ecology, University of Antwerp, Antwerp, Belgium ; Department of Terrestrial Zoology, Naturalis Biodiversity Center, Leiden, The Netherlands.

ABSTRACT
Fluctuating asymmetry (FA), as an indirect measure of developmental instability (DI), has been intensively studied for associations with stress and fitness. Patterns, however, appear heterogeneous and the underlying causes remain largely unknown. One aspect that has received relatively little attention in the literature is the consequence of direct mechanical effects on asymmetries. The crucial prerequisite for FA to reflect DI is that environmental conditions on both sides should be identical. This condition may be violated during early human development if amniotic fluid volume is deficient, as the resulting mechanical pressures may increase asymmetries. Indeed, we showed that limb bones of deceased human fetuses exhibited increased asymmetry, when there was not sufficient amniotic fluid (and, thus, space) in the uterine cavity. As amniotic fluid deficiency is known to cause substantial asymmetries and abnormal limb development, these subtle asymmetries are probably at least in part caused by the mechanical pressures. On the other hand, deficiencies in amniotic fluid volume are known to be associated with other congenital abnormalities that may disturb DI. More specifically, urogenital abnormalities can directly affect/reduce amniotic fluid volume. We disentangled the direct mechanical effects on FA from the indirect effects of urogenital abnormalities, the latter presumably representing DI. We discovered that both factors contributed significantly to the increase in FA. However, the direct mechanical effect of uterine pressure, albeit statistically significant, appeared less important than the effects of urogenital abnormalities, with an effect size only two-third as large. We, thus, conclude that correcting for the relevant direct factors allowed for a representative test of the association between DI and stress, and confirmed that fetuses form a suitable model system to increase our understanding in patterns of FA and symmetry development.

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Correspondence analysis between different congenital abnormalities and amniotic fluid volumes.The correspondence analysis visualizes the contingency between the different types of congenital abnormalities and amniotic fluid volumes. The closer groups are located to each other, the stronger the correlation between the groups is. The horizontal-axis accounts for 70.7% of the variation and the vertical-axis for 19.9%. The significance of relationships between types of amniotic fluid volumes and congenital abnormalities is calculated using chi-squared tests. Oligohydramnios (OH) and anhydramnios (AH) associate significantly with urogenital defects (UG) and polyhydramnion (PH) with muscular system malformations (MUS), but not significantly after bonferroni adjustment. Normal amniotic fluid volumes associate with nervous system defects, but not significantly after bonferroni adjustment. No associations are found between cardiovascular defects (CV), skeletal defects (SK), craniofacial defects (CF), limb development abnormalities (LD), digestive system defects (DS), and ventral body wall defects (VBW) and the different types of amniotic fluid volume.
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pone-0081824-g003: Correspondence analysis between different congenital abnormalities and amniotic fluid volumes.The correspondence analysis visualizes the contingency between the different types of congenital abnormalities and amniotic fluid volumes. The closer groups are located to each other, the stronger the correlation between the groups is. The horizontal-axis accounts for 70.7% of the variation and the vertical-axis for 19.9%. The significance of relationships between types of amniotic fluid volumes and congenital abnormalities is calculated using chi-squared tests. Oligohydramnios (OH) and anhydramnios (AH) associate significantly with urogenital defects (UG) and polyhydramnion (PH) with muscular system malformations (MUS), but not significantly after bonferroni adjustment. Normal amniotic fluid volumes associate with nervous system defects, but not significantly after bonferroni adjustment. No associations are found between cardiovascular defects (CV), skeletal defects (SK), craniofacial defects (CF), limb development abnormalities (LD), digestive system defects (DS), and ventral body wall defects (VBW) and the different types of amniotic fluid volume.

Mentions: We examined the associations between congenital abnormalities in the different organ systems and the different amniotic fluid volumes (NV (N=606), AH (N=19), OH (N=42), and PH (N=35)) in a correspondence analysis (Figure 3). The first dimension (horizontal-axis) accounted for 70.7% of the variation and the second dimension (vertical-axis) for 19.9%. The correspondence analysis map of Figure 3 shows that both OH and AH correspond with urogenital problems in the lower left quadrant, i.e. a contingency between OH/AH and UG exists and these variables are thus not independent from each other. PH corresponds with muscular system malformations in the lower right quadrant. Χ2 – tests based on the contingency table of the correspondence analysis confirmed that the distribution of congenital abnormalities over the different groups of amniotic fluid volume are not independent for muscular abnormalities (MUS), nervous system abnormalities (NS) and urogenital abnormalities (UG), of which only UG abnormalities remained significant after Bonferroni correction (table 2). Relationships are independent for bronchopulmonary abnormalities (BP), craniofacial abnormalities (CF), cardiovascular abnormalities (CV), digestive system abnormalities (DS), limb defects (LD), skeletal defects (SK), and ventral body wall defects (VBW) (table 2).


Amniotic fluid deficiency and congenital abnormalities both influence fluctuating asymmetry in developing limbs of human deceased fetuses.

ten Broek CM, Bots J, Varela-Lasheras I, Bugiani M, Galis F, Van Dongen S - PLoS ONE (2013)

Correspondence analysis between different congenital abnormalities and amniotic fluid volumes.The correspondence analysis visualizes the contingency between the different types of congenital abnormalities and amniotic fluid volumes. The closer groups are located to each other, the stronger the correlation between the groups is. The horizontal-axis accounts for 70.7% of the variation and the vertical-axis for 19.9%. The significance of relationships between types of amniotic fluid volumes and congenital abnormalities is calculated using chi-squared tests. Oligohydramnios (OH) and anhydramnios (AH) associate significantly with urogenital defects (UG) and polyhydramnion (PH) with muscular system malformations (MUS), but not significantly after bonferroni adjustment. Normal amniotic fluid volumes associate with nervous system defects, but not significantly after bonferroni adjustment. No associations are found between cardiovascular defects (CV), skeletal defects (SK), craniofacial defects (CF), limb development abnormalities (LD), digestive system defects (DS), and ventral body wall defects (VBW) and the different types of amniotic fluid volume.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842303&req=5

pone-0081824-g003: Correspondence analysis between different congenital abnormalities and amniotic fluid volumes.The correspondence analysis visualizes the contingency between the different types of congenital abnormalities and amniotic fluid volumes. The closer groups are located to each other, the stronger the correlation between the groups is. The horizontal-axis accounts for 70.7% of the variation and the vertical-axis for 19.9%. The significance of relationships between types of amniotic fluid volumes and congenital abnormalities is calculated using chi-squared tests. Oligohydramnios (OH) and anhydramnios (AH) associate significantly with urogenital defects (UG) and polyhydramnion (PH) with muscular system malformations (MUS), but not significantly after bonferroni adjustment. Normal amniotic fluid volumes associate with nervous system defects, but not significantly after bonferroni adjustment. No associations are found between cardiovascular defects (CV), skeletal defects (SK), craniofacial defects (CF), limb development abnormalities (LD), digestive system defects (DS), and ventral body wall defects (VBW) and the different types of amniotic fluid volume.
Mentions: We examined the associations between congenital abnormalities in the different organ systems and the different amniotic fluid volumes (NV (N=606), AH (N=19), OH (N=42), and PH (N=35)) in a correspondence analysis (Figure 3). The first dimension (horizontal-axis) accounted for 70.7% of the variation and the second dimension (vertical-axis) for 19.9%. The correspondence analysis map of Figure 3 shows that both OH and AH correspond with urogenital problems in the lower left quadrant, i.e. a contingency between OH/AH and UG exists and these variables are thus not independent from each other. PH corresponds with muscular system malformations in the lower right quadrant. Χ2 – tests based on the contingency table of the correspondence analysis confirmed that the distribution of congenital abnormalities over the different groups of amniotic fluid volume are not independent for muscular abnormalities (MUS), nervous system abnormalities (NS) and urogenital abnormalities (UG), of which only UG abnormalities remained significant after Bonferroni correction (table 2). Relationships are independent for bronchopulmonary abnormalities (BP), craniofacial abnormalities (CF), cardiovascular abnormalities (CV), digestive system abnormalities (DS), limb defects (LD), skeletal defects (SK), and ventral body wall defects (VBW) (table 2).

Bottom Line: One aspect that has received relatively little attention in the literature is the consequence of direct mechanical effects on asymmetries.We discovered that both factors contributed significantly to the increase in FA.We, thus, conclude that correcting for the relevant direct factors allowed for a representative test of the association between DI and stress, and confirmed that fetuses form a suitable model system to increase our understanding in patterns of FA and symmetry development.

View Article: PubMed Central - PubMed

Affiliation: Group of Evolutionary Ecology, University of Antwerp, Antwerp, Belgium ; Department of Terrestrial Zoology, Naturalis Biodiversity Center, Leiden, The Netherlands.

ABSTRACT
Fluctuating asymmetry (FA), as an indirect measure of developmental instability (DI), has been intensively studied for associations with stress and fitness. Patterns, however, appear heterogeneous and the underlying causes remain largely unknown. One aspect that has received relatively little attention in the literature is the consequence of direct mechanical effects on asymmetries. The crucial prerequisite for FA to reflect DI is that environmental conditions on both sides should be identical. This condition may be violated during early human development if amniotic fluid volume is deficient, as the resulting mechanical pressures may increase asymmetries. Indeed, we showed that limb bones of deceased human fetuses exhibited increased asymmetry, when there was not sufficient amniotic fluid (and, thus, space) in the uterine cavity. As amniotic fluid deficiency is known to cause substantial asymmetries and abnormal limb development, these subtle asymmetries are probably at least in part caused by the mechanical pressures. On the other hand, deficiencies in amniotic fluid volume are known to be associated with other congenital abnormalities that may disturb DI. More specifically, urogenital abnormalities can directly affect/reduce amniotic fluid volume. We disentangled the direct mechanical effects on FA from the indirect effects of urogenital abnormalities, the latter presumably representing DI. We discovered that both factors contributed significantly to the increase in FA. However, the direct mechanical effect of uterine pressure, albeit statistically significant, appeared less important than the effects of urogenital abnormalities, with an effect size only two-third as large. We, thus, conclude that correcting for the relevant direct factors allowed for a representative test of the association between DI and stress, and confirmed that fetuses form a suitable model system to increase our understanding in patterns of FA and symmetry development.

Show MeSH
Related in: MedlinePlus