Unstable allele; mutates spontaneously at a high rate, both germinally and somatically. Two classes of reversions are observed in approximately equal frequency; reversion to a m allele with an intermediate phenotype ("mi" exemplified by mi27) and reversion to a subliminal m allele equivalent to wild type in phenotype ("ms" exemplified by ms19).
Unstable allele; mutates spontaneously at a high rate, both germinally and somatically. Two classes of reversions are observed in approximately equal frequency; reversion to a m allele with an intermediate phenotype ("mi" exemplified by mi27) and reversion to a subliminal m allele equivalent to wild type in phenotype ("ms" exemplified by ms19).