Detection of candidate chromosome for cleft lip with palate in A/WySn mice

Non-syndromic cleft lip with palate (CLP) represents one of the many craniofacial malformations identified in humans. The etiology underlying CLP are complex and highly variable. A/WySn mice serve as an intriguing model for human CLP, as they develop this dysmorphology with a variable expression pattern, incomplete penetrance and frequently demonstrate unilateral expression on a homogeneous genetic background. The developmental basis for these variations in expression is unknown. In the present study, the authors performed interval mapping and linkage analysis on the first backcross segregates of a cross between A/WySn and C57BL/6J (N2 generation) mice affected with CLP using 99 informative Mit markers that have been previously determined. To ensure for the CLP trait, we observed mouse embryos on embryonic day 18 (E18), as palatal fusion does not occur prior to E16 in mice. 39 CLP affected individuals were identified in the 3,018 living N2 backcross embryos. Two highly significant linkage regions on chromosome 11 (flanked by D11Mit245 and D11Mit203 markers) and chromosome 13 (flanked by D13Mit179 and D13Mit293 markers), respectively were obtained (χ2, P < 0.001). These findings suggested that candidate genes for CLP in the A/WySn mouse strain are located on chromosomes 11 and 13.