Imprecise excision of the element in roX1MB710, removing bases 283-2669 of roX1.
viable
Df(1)52, Polr2A+tcos4Δ4.3, lncRNA:roX1ex7B has partially lethal - majority live | male phenotype
roX1ex7B Df(1)52 hemizygous males with P{w+4Δ4.3} are semi-viable: 43% survive to adulthood.