Scientists report that knocking out the Lsdia1 gene using CRISPR in the freshwater snail Lymnaea stagnalis reverses the direction of shell coiling. The snail shell typically coils in the right-handed or dextral direction, but the snails with the Lsdia1 gene knocked out coil in a left-handed or sinistral direction.
M. Abe, R. Kuroda, “The development of CRISPR for a mollusc establishes the formin Lsdia1 as the long-sought gene for snail dextral/sinistral coiling,” Development, doi:10.1242/dev.175976, 2019.