- The mouse Spam1 maps to proximal chromosome 6 and is a candidate for the sperm dysfunction in Rb(6.16)24Lub and Rb(6.15)1Ald heterozygotes. Deng, X., Moran, J., Copeland, N.G., Gilbert, D.J., Jenkins, N.A., Primakoff, P., Martin-DeLeon, P.A. Mamm. Genome (1997)