Drosophila spalt/spalt-related mutants exhibit Townes--Brocks' syndrome phenotypes

Mutations in SALL1, the human homolog of the Drosophila spalt gene, result in Townes-Brocks' syndrome, which is characterized by hand/foot, anogenital, renal, and ear anomalies, including sensorineural deafness, spalt genes encode zinc finger transcription factors that are found in animals as diverse as worms, insects, and vertebrates. Here, we examine the effect of losing both of the spalt genes, spalt and spalt-related, in the fruit fly Drosophila melanogaster, and report defects similar to those in humans with Townes-Brocks' syndrome. Loss of both spalt and spalt-related function in flies yields morphological defects in the testes, genitalia, and the antenna. Furthermore, spalt/spalt-related mutant antennae show severe reductions in Johnston's organ, the major auditory organ in Drosophila. Electrophysiological analyses confirm that spalt/spalt-related mutant flies are deaf. These commonalities suggest that there is functional conservation for spalt genes between vertebrates and insects.