Updated by: Arabinda Naik
Pleiotropy is a genetic condition when a single gene influences two or more distinct phenotypic characteristics or traits, i.e., a single gene influences multiple trait. In some organisms like Drosophila, human and several fishes, a single gene is responsible for the expression of sex. In Drosophila tra (transformer), a recessive gene, present on the third autosome expresses the sex. Most males and females with dominant allele (tra+) are fertile. But a normal female (AA + XX) when homozygous recessive with both tra alleles develop as sterile male. In human a sty (sex determining region Y), present on the Y chromosome influences the development of testes in the male and its absence develops ovaries in the female. Therefore, XX female with sry gene is a sterile female and a XY male without sry gene too is a sterile female.