Craniofacial variability and morphological integration in mice susceptible to cleft lip and palate

A/WySnJ mice are an inbred strain that develops cleft lip with or without cleft palate (CL/P) with a frequency of 25–30% and a predominantly unilateral expression pattern. As in humans, the pattern of incomplete penetrance, and variable and frequent unilateral expression suggests a role for altered regulation of variability (developmental stability, canalization and developmental integration) during growth. We compared both mean and variability parameters for craniofacial shape and size among A/WySnJ mice, a strain that does not develop CL/P (C57BL/6J) and their F1 cross. We show that adult A/WySnJ mice that do not express cleft lip exhibit decreased morphological integration of the cranium and that the co-ordination of overall shape and size variation is disrupted compared with both C57BL/6J mice and the F1 cross. The decrease in integration is most pronounced in the palate and face. The absence of this pattern in the F1 cross suggests that it is determined by recessive genetic factors. By contrast, the shape differences between the strains, which are thought to predispose A/WySnJ mice to CL/P, show a range of dominance which suggests a polygenic basis. We suggest that decreased integration of craniofacial growth may be an aetiological factor for CL/P in A/WySnJ mice

Epigenome analyses using BAC microarrays identify evolutionary conservation of tissue-specific methylation of SHANK3

CpG islands are present in one-half of all human and mouse genes and typically overlap with promoters or exons. We developed a method for high-resolution analysis of the methylation status of CpG islands genome-wide, using arrays of BAC clones and the methylation-sensitive restriction enzyme NotI. Here we demonstrate the accuracy and specificity of the method. By computationally mapping all NotI sites, methylation events can be defined with single-nucleotide precision throughout the genome. We also demonstrate the unique expandability of the array method using a different methylation-sensitive restriction enzyme, BssHII. We identified and validated new CpG island loci that are methylated in a tissue-specific manner in normal human tissues. The methylation status of the CpG islands is associated with gene expression for several genes, including SHANK3, which encodes a structural protein in neuronal postsynaptic densities. Defects in SHANK3 seem to underlie human 22q13 deletion syndrome. Furthermore, these patterns for SHANK3 are conserved in mice and rats