PDGFR is crucial for the maturation of the testes and differentiation of Leydig cells, while PDGFR-A is necessary for the recruitment of Leydig cells and spermatogenesis, resulting in a change in the estrogen-to-androgen ratio and a decrease in testosterone levels, which can encourage the development of gynecomastia. The gene discussed is PDGFRB; the disease is Gynecomastia.