The midsagittal area of the corpus callosum expressed as the percentage of the hemispheric surface is smaller in the NZB/BlNJ than in the C57BL/6By inbred strain of mice. We performed a QTL mapping analysis using 284 F2s. Two loci linked to this measure were found: the CCrSQTL1 and CCrSQTL2 at 87 and 67 centiMorgans from the centromere on chromosomes 1 and 4 respectively. The two loci interacted significantly. The total source of genetic variation contributed to 25% of the observed variance.
