DEVELOPMENT OF A STRAIN OF RABBITS WITH CONGENITAL SIMPLE NONSYNDROMIC CORONAL SUTURE SYNOSTOSIS .1. BREEDING DEMOGRAPHICS, INHERITANCE PATTERN, AND CRANIOFACIAL ANOMALIES

The lack of an animal model of congenital coronal suture (CS) synostos is has prompted the widespread use of an experimental rabbit model usi ng adhesive immobilization of the CS. Such postnatal models have helpe d make significant scientific contributions but may still not fully re present all aspects of the human congenital condition. In the March 19 93 issue of The Cleft Palate-Craniofacial Journal we reported a female rabbit born in our laboratory with complete bilateral CS synostosis. This follow-up study presents our attempts to breed this animal and es tablish a strain of craniosynostotic rabbits. To date, we have accompl ished 10 back- and intercrosses with these animals and have produced a total of 71 live offspring; 10 animals exhibited complete nonsyndromi c unilateral (plagiocephalic) or bilateral (brachycephalic) CS synosto tic deformities at birth, and 19 animals exhibited partial CS synostos is that showed more than 75% growth retardation across the CS (well be low the 95% confidence interval for normals). Results revealed that ge stational time and litter size averages were consistent with those rep orted for the strain, although the average litter size decreased with increased inbreeding. By 1.5 weeks of age the completely synostosed an imals already exhibited brachycephalic cranial vaults and midfacial hy poplasia compared to unaffected siblings. Initial pedigree analysis su ggested an autosomal dominant inheritance pattern with incomplete pene trance and variable expressivity. The development of such a congenital rabbit model may prove useful in helping to understand the etiopathog enesis of this condition in human populations.