Reproductive efficiency of wild type and SP hyh mice.

wt: wild type (Napa(+/+)); het: heterozygous (Napa(hyh/+)); hyh: mutant homozygous (Napa(hyh/hyh)) with the slow progressive phenotype. aMatings are considered “productive” if at least one offspring was born. b“Relative fecundity” is obtained as: (productive mating/100)×(litter size)×(number of litters); the value obtained is a measure of the overall fecundity according to the Handbook of Genetically Standardized JAX Mice [33]. cThe same hyh male had two productive matings.