Newborn and adult face shapes related to mouse cleft lip predisposition

Embryonic face shape was postulated to be a factor in the multifactorial basis for susceptibility to cleft lip (CL) in A/J mice, since A/J differed from C57BL/6 (resistant embryos). To test this hypothesis new lines were created by selection and the embryos measured (Juriloff and Trasler, 1976). The L line with 9% CL had the predicted narrow internasal pit distance like A/J (12% CL) compared to the M line (0% CL) like the resistant C57BL/6 (0% CL). Newborns and adults of these four lines and CL/Fr (23% CL) were measured to find whether they, like embryos, have face shapes related to their CL predisposition. Measurements were made on newborn and 2 1/2 month old mouse skulls and on heads fixed for soft tissue. Premaxilla length (PL, distance from incisive foramen to anterior edge of anterior palatine foramen) was significantly shorter in newborns and adults in CL lines CL/Fr, A/J and L than non‐CL lines M and C57BL/6. Premaxilla width (PW) tended to be narrower in adults (except A/J) and gum (i.e. filtrum) length (GL) in newborns and adults tended to be shorter in CL lines. Discriminant analysis of adult skeletal data involving four variables PL, PW, Interorbital distance (ID) and length of nasal bones (LN) discriminated A/J and L from M and C57BL/6 lines. Discriminant analysis with ID omitted discriminated CL lines A/J, L and CL/Fr from non‐CL lines M and C57. For variables PL, LN and ID in newborn skulls discriminant analysis had less discriminating ability, but showed a strong tendency to separate A/J and L from C57 and M. Thus a particular facial complex associated with CL predisposition has been found.