For example, in the case of the testis-specific SEPT12, mutants that affect GTP binding and hydrolysis resulted in distinguishable phenotypes in terms of sperm morphology and motility, but were both associated with infertility (Kuo et al., 2012 ▸; Kuo et al., 2015 ▸). The gene discussed is SEPTIN12; the disease is Infertility.