A GENE AFFECTING WALLERIAN NERVE DEGENERATION MAPS DISTALLY ON MOUSE CHROMOSOME-4

When a nerve axon is cut or crushed, the nerve fibers in the distal pa rt of the axon, separated from the cell body, undergo a form of sponta neous degeneration, known as Wallerian degeneration. A substrain of th e mouse inbred strain C57BL, known as C57BL/Ola, carries a mutant form of a gene involved in Wallerian degeneration in the peripheral and ce ntral nervous systems, and in retrograde degeneration of retinal gangl ion cells. Wallerian degeneration in this substrain is abnormally slow . Previously the defect had been shown to be due to an autosomal domin ant gene. The locus has been given the name and symbol Wallerian degen eration Wld, with the mutant allele Wld(s) (Wallerian degeneration-slo w). The Wld locus has now been mapped, by using conventional and molec ular markers, to the distal end of chromosome 4, near the locus of pro natriodilatin (Pnd). The order of loci (with recombination distances i n centimorgans, cM) is cen-D4Mit11-8.9 +/- 1.7 cM-Fuca-2.5 +/- 0.93 cM -Akp-2-3.2 +/- 1.1 cM-D4Mit48-3.5 +/- 1.1 cM-(Wld, Pnd, D4Mit49)-0.71 +/- 0.50 cM-(Eno-1, D4Mit33)-1.4 +/- 0.70 cM-D4Mit42-2.5 +/- 0.93 cM-D 4Smh6b. The information on the position of the Wld locus should be val uable in further characterization of this gene involved in nerve degen eration and regeneration.