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Phenotypic variability and craniofacial dysmorphology: increased shape variance in a mouse model for cleft lip
Author(s) -
Parsons Trish E.,
Kristensen Erika,
Hornung Lynnette,
Diewert Virginia M.,
Boyd Steven K.,
German Rebecca Z.,
Hallgrímsson Benedikt
Publication year - 2008
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/j.1469-7580.2007.00845.x
Subject(s) - craniofacial , biology , penetrance , embryo , phenotype , genetics , inbred strain , analysis of variance , homogeneous , variable expression , genetic variation , anatomy , medicine , gene , physics , thermodynamics
Cleft lip and palate (CL/P), as is true of many craniofacial malformations in humans, is etiologically complex and highly variable in expression. A/WySn mice are an intriguing model for human CL/P because they develop this dysmorphology with a variable expression pattern, incomplete penetrance and frequent unilateral expression on a homogeneous genetic background. The developmental basis for this variation in expression is unknown, but of great significance for understanding such expression patterns in humans. As a step towards this goal, this study used three‐dimensional geometric morphometric and novel high throughput morphometric techniques based on three‐dimensional computed microtomography of mouse embryos to analyze craniofacial shape variation during primary palate formation. Our analysis confirmed previous findings based on two‐dimensional analyses that the midface in A/WySn embryos, and the maxillary prominence in particular, is relatively reduced in size and appears to be developmentally delayed. In addition, we find that shape variance is increased in A/WySn embryos during primary palate formation compared to both C57BL/6J mice and the F1 crosses between these strains. If the reduction in midfacial growth caused by the Wnt9b hypomorphic mutation pushes A/WySn mice closer on average to the threshold for cleft lip formation, the elevated shape variance may explain why some, but not all, embryos develop the dysmorphology in a genetically homogeneous inbred line of mice.