ACOX1 and obesity due to melanocortin 4 receptor deficiency: However, in the case of the acox1, pcsk9, and furin genes, a significant effect of the obesity factor alone was detected (found for the genes acox1 (F (1, 20) = 24.00; p < 0.0001; for), pcsk9 (F (1, 20) = 94.77; p < 0.0001; for), and furin (F (1, 20) = 17.88; p = 0.0004).