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. 2015 Apr;167A(4):688-94.
doi: 10.1002/ajmg.a.36963. Epub 2015 Feb 5.

Phenotypic sub-grouping in microtia using a statistical and a clinical approach

Daniela V Luquetti  1 , Babette S Saltzman, Carrie L Heike, Kathleen C Sie, Craig B Birgfeld, Kelly N Evans, Brian G Leroux
Affiliations

Phenotypic sub-grouping in microtia using a statistical and a clinical approach

Daniela V Luquetti et al. Am J Med Genet A. 2015 Apr.

Abstract

The clinical presentation of microtia varies widely from minimal morphological abnormalities to complete absence of the ear. In this study we sought to identify and characterize sub-groups of microtia using a statistical and a clinical approach. Photographs of 86 ears were classified in relation to all the external ear components. We used cluster analysis and rater's clinical opinion to identify groups with similar phenotypes in two separate analyses. We used Cramer's Phi coefficient of association to assess the similarity among the clinician's groupings as well as among the statistical sub-phenotypic groups and each of the clinician's groupings. The cluster analysis initially divided the 86 ears into a more and a less severe group. The less severe group included two sub-groups that included ears classified as normal and a group that had very few anomalous components. The group of 48 more affected ears all had abnormalities of the helix crus; antihelix-stem, -superior crus and -inferior crus; and antitragus. These were further divided into 4 sub-phenotypes. There was a moderate degree of association among the raters' groupings (Cramer's Phi: 0.64 to 0.73). The statistical and clinical groupings had a lower degree of association (Cramer's Phi: 0.49 to 0.58). Using standardized characterization of structural abnormalities of the ear we identified six distinct phenotypic groups; correlations with clinicians' groupings were moderate. These clusters may represent groups of ear malformations associated with the same etiology, similar time of insult or target cell population during embryonic development. The results will help inform investigations on etiology.

Keywords: ear morphology; microtia; phenotype.

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Figures

Figure 1
Figure 1
Photos of the 86 ears distributed in the six identified clusters: A1, A2, B1.1.1, B1.1.2, B1.2 and B2. Marx classification of each ear, performed in the prior study, are shown as underscore below wach image. (Images courtesy of Photographer Erik Stuhaug)
See this image and copyright information in PMC

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