Effects of the Y‐chromosome and the dominant hemimelia mutation on the morphology of the mouse mandible

The aims of this study were to test whether the Y‐chromosome and the autosomal dominant hemimelia (Dh) mutation can affect mandible morphology in mice. I analyzed mandible size and shape using landmark‐based geometric morphometrics in 16 DH‐Chr Y^@‐+/+ (@ represents one of the inbred strain names) strains and observed significant differences in mandible size. The largest mandible was identified in strain DH‐Chr Y^C3H and the smallest in strain DH‐Chr Y^KK. Canonical variate and discriminant function analyses suggested that the mandible shapes of strains DH‐Chr Y^C3H and DH‐Chr Y^KK differed from those of the other strains. Because seven of the DH‐Chr Y^@‐+/+ strains were maintained with dominant hemimelia, I also analyzed the potential influence of dominant hemimelia on mandible morphology because dominant hemimelia is known to cause various skeletal malformations. There were no significant differences in mandible size in seven sets of DH‐Chr Y^@‐+/+ and DH‐Chr Y^@‐Dh/+ strains. However, canonical variate analysis mapped strains DH‐Chr Y^CAS‐Dh/+ and DH‐Chr Y^CBA‐Dh/+ mapped distantly from the rest. Additionally, I observed similar patterns of shape change between DH‐Chr Y^CAS‐+/+ and DH‐Chr Y^CAS‐Dh/+, and between DH‐Chr Y^CBA‐+/+ and DH‐Chr Y^CBA‐Dh/+. These data indicate that the Y‐chromosome affects the size and shape of the mouse mandible. Dominant hemimelia affects mandible shape but not size, and its effects emerge depending on the kinds of Y‐chromosomes.