HIF1A and sleep apnea syndrome: On the other hand, those patients with CM and high HIF-1α expression showed significantly more CM aggressiveness markers, including increased mitotic index, higher Breslow index, the presence of ulceration and proportion of positive sentinel nodes (Table 5), and greater SDB severity regarding their corresponding DI4% (near statistically significant association: p = 0.08) and nadir SpO2 values (Table 6).