Practice question

Sex reversal in mammals can occur through mutations in multiple genes because gonadal fate depends on balanced antagonistic loops. Loss of ovary-promoting genes Wnt4, Rspo1, Foxl2 or β-catenin derepresses Sox9 leading to XX testes, while duplication or enhancer activation of Sox9 itself also causes XX sex reversal. Conversely loss of Sox9, Sf1 or Fgf9 causes XY male-to-female reversal with ovaries. Mutations affecting β-catenin stabilization produce similar phenotypes. Since testis and ovary programs mutually inhibit each other, disrupting any node can tilt balance, therefore correct answer includes all listed genes as capable of causing reversal.