ITIH1 and familial hyperinsulinism: Low expression of ITIH4 347–356 (Peak 1, m/z: 1061.91) and ITIH1 205–214 (Peak 2, m/z: 1088.33) in HHI serum samples at sea level may play a significant role in the pathology of HHI by affecting the conditions of vascular endothelial cells.