Locus on chromosome 16 is significantly associated with increased tendency to lose pups in females of the RR/Sgn inbred mouse strain

Females of the inbred mouse strain RR/Sgn have an apparent tendency to lose pups during rearing. To identify genes underlying this abnormal maternal phenotype, we performed quantitative trait loci (QTL) mapping in 349 (C57BL/6 J × RR/Sgn) F 1  × RR/Sgn backcross mice and identified one significant and one suggestive QTL on chromosomes 16 and 4, respectively. We assigned the gene symbol nurturing ability QTL 3 ( Naq3 ) to the QTL on chromosome 16. Twenty of the 21 mothers who lost entire litters were homozygous for RR/Sgn allele at Naq3 ; i.e., the significant association of Naq3 with pup loss was further confirmed by binomial tests. We tentatively propose that Mapk1 , Kalrn , and Vps8 are potential candidate genes for Naq3 .