Soft tissue facial resemblance in families and syndrome-affected individuals

Abstract

We investigated soft tissue facial resemblance among relatives with or without syndromes and among related and unrelated individuals diagnosed with the same syndrome. Using correlation coefficients, we compared facial landmark (i.e., three-dimensional coordinate) positions and measurements gained by photogrammetry in various combinations of normal and syndrome-affected individuals. There were fewer significant correlations for the three-dimensional coordinates and measurements between the normal parent-normal child pairs than for the normal sib pairs. There was no discernible pattern for the single measurements in the parent-child pairs, whereas all of the midline vertical measurements were significantly positively correlated in the normal sib pairs. Significant correlations were always positive in all sib comparisons, but ranged from negative to positive in all parent-child correlations. The shared environment of sibs was a possible explanation for their greater resemblance in comparison with parent-child pairs. We also had measurements from 11 subjects (related and unrelated) diagnosed with one of four syndromes, and we used these to compare individuals with the same syndrome by calculating correlation coefficients based on all available pairs of measurements. The highest significant positive correlations were found for related individuals with the same syndrome (0.72 to 0.83). Unrelated individuals with the same syndrome also had significant positive correlations, but they were lower (0.35 to 0.65). We therefore inferred that the genetic similarities between unrelated individuals with syndromes played a role in the resemblance between them, and that common genes and environment in related individuals further contributed to the high correlations found for them.

Computer-based recognition of dysmorphic faces

“…The presence of a specific facial pattern in patients with a genetic syndrome indicates that there is consistency in the phenotypic expression of the affected genes. 1 Compared to the recognition of familiar faces, the recognition of a disease-specific facial pattern in unrelated individuals is much more difficult, because it requires the skill to extract such a pattern from the facial appearance that is also influenced by family background and environment. Experienced geneticists can do this relatively well, but computers have so far been unable to do this.…”

The Influence of trisomy 21 on facial form and variability

“…It has been argued that trisomy 21 alters facial morphology sufficiently to obscure family resemblance completely (Opitz & Gilbert‐Barness, ), although previous quantitative attempts to evaluate facial similarity between individuals with DS and their siblings were inconclusive (Shaner, Peterson, Beattie, & Bamforth, ). In samples of unaffected individuals, the resemblance between relatives is easily recognized by most observers, and different studies have shown that facial dimensions of both osseous and soft tissue are heritable (Baydas, Erdem, Yavuz, & Ceylan, ; Sherwood et al, ).…”

Quantitative Evaluation of the Facial Morphology of a Tolteca Figurine from Mexico using Geometric Morphometric Approaches

“…Other factors that affect facial appearance include inter-and intra-population differences, sex, and age. As a result of these influences, DS individuals tend to resemble each other, but often also resemble their family members (Shaner et al, 2001). …”