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Testing the face shape hypothesis in twins discordant for nonsyndromic orofacial clefting
Author(s) -
Roosenboom Jasmien,
Indencleef Karlijne,
Hens Greet,
Peeters Hilde,
Christensen Kaare,
Marazita Mary L.,
Claes Peter,
Leslie Elizabeth J.,
Weinberg Seth M.
Publication year - 2017
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.38471
Subject(s) - dizygotic twins , twin study , monozygotic twin , dizygotic twin , forehead , phenotype , zygosity , biology , genetics , heritability , audiology , medicine , anatomy , gene , obstetrics
Nonsyndromic orofacial clefts (OFCs) are complex traits characterized by multifactorial inheritance and wide phenotypic variability. Numerous studies have shown subtle differences in the faces of unaffected relatives from cleft families compared to controls, the implication being that such outward differences are an incomplete expression reflecting an underlying genetic predisposition. Twins discordant for OFCs provide a unique opportunity to further test this idea, as the unaffected co‐twin shares on average 50% (for dizygotic twins) and 100% (for monozygotic twins) of the genetic risk factors as the affected twin. We used 3D surface imaging and spatially‐dense morphometry to compare facial shape in a sample of 44 unaffected co‐twins and age‐ and sex‐matched unaffected controls ( n = 241). Unaffected co‐twins showed statistically significant differences in the midface, lateral upper face, and forehead regions, compared to controls. Furthermore, co‐twins were characterized by a distinct pattern of midfacial retrusion, broader upper faces, and greater protrusion of the mandible and brow ridges. This same general facial pattern was shown in both unaffected monozygotic and dizygotic co‐twin subsets. These results provide additional support that altered facial shape is a phenotypic marker for OFC susceptibility.