Craniosynostosis with autosomal dominant transmission in New Zealand white rabbits

Although great strides have been made recently in determining the etiology of a number of human craniosynostotic syndromes, pathogenic mechanisms for these conditions are still unclear, in part because of the lack of a genetic animal model with primary craniosynostosis. Recently, we developed an inbred colony of rabbits with congenital coronal suture synostosis. The present study describes long term breeding demographics, karyotypes, and pedigree analysis from this colony in an effort to characterize the genotype and mode of inheritance of craniosynostosis for future etiopathogenic studies. Seventy-six consecutive back- and intercrosses resulted in 46 fetal and term litters and produced 135 normal offspring and 163 affected offspring with either partial or complete coronal suture synostosis. Conception rate, litter size, and gestation length were normal, and karyotype analysis revealed no gross chromosomal abnormalities. Pedigree analysis of the segregation rates observed for each rabbit litter suggests that the craniosynostosis seen in this pedigree is inherited in an autosomal dominant fashion with reduced penetrance and variable expression. Results revealed that the mode of inheritance and phenotypic variability noted in this colony closely parallel the human craniosynostotic condition and several possible candidate gene families are discussed. The utility of developing such a congenital animal model is evident and may lead to a better understanding of gene expression, normal suture morphogenesis, and the pathogenesis of craniosynostosis.