Mhc^T178I homozygosity in a Mhc¹⁰ background induces a flightless phenotype and adults typically display a wings-up phenotype; the heterozygosity condition also leads to a significant and progressive decrease in flight ability.

In the Mhc^T178I, Mhc¹⁰ double homozygosity condition, pupal indirect flight muscles show assembly defects with disrupted myofibril morphology (myofilament subdomains with myofibrils that are poorly aligned with each other and fraying of filaments); 2h-old adult indirect flight muscles show extreme disruption in morphology (thick filaments dispersed in myofibril remnants and reduction in regular sarcomere patterns); 2 days-old adult indirect flight muscles show continued disruption in myofibril morphology (no regular sarcomeric structures and Z-band material scattered throughout the myofibril remnants). In the Mhc^T178I/+, Mhc¹⁰/Mhc¹⁰ condition, the pupal and 2h-old adult indirect flight muscles show no obvious defects; however, 2 days-old adult indirect flight muscles show some disruption in myofibril morphology (myofilaments are missing from the lattice and the sarcomere structural elements are disrupted); in 7 days-old adults there is a severe muscle degeneration.