Mice that are homozygous for this spontaneous mutation die just after birth from an in ability to breathe. Newborns exhibit cleft palate, a protruding tongue, bulging abdomen, enlarged liver and a shortened trunk, limbs, snout and tail. Long bones measure half the length of wild-type mice and the spinal column is reduced by 25%. Cartilage in homozygous mice consists of densely packed chrondocytes, little matrix, pycnotic cells and unusual amounts of collagen fibers.
Mice that are heterozygous for the mutation appear normal at birth, but develop proportional dwarfism by 28 days. Aging mice exhibit spinal misalignment and degeneration followed by the sudden onset of a spastic gait and an accompanying decrease in movement. Mice die within one month following the appearance of the abnormal gait. Heterozygotes do not live beyond 19 months.
This mutant mouse strain may be useful in studies of achondroplasia, disc herniation and spinal degeneration.
