A novel duplication present in a subset of the Ax3 lineage. Nine strains in our study are lineal descendants of Ax3, and one other carries one or more chromosomes from it. NC4A2, based on our evidence, also descends from Ax3. Of these 12 lines, 7 carry a near identical duplication of chromosome 5 sequence. The breakpoints are not entirely clear because of noise in the data, and it is possible that there is some difference between strains. The genes plotted here are: a, DDB0188657; b, DDB0219507; c, DDB0188659; d, DDB0188660; e, DDB0188661; f, DDB0188665; g, DDB0188667; h, DDB0216146; i, DDB0188671; j, DDB0188673; k, DDB0188674; l, DDB0188677; m, DDB0188678; n, DDB0188686; o, DDB0188687; and p, DDB0188688.