CCR2 and congenital isolated hyperinsulinism: Decreased CCR2 expression may be responsible for the death of infected progenitor cells in the bone marrow which results in a reduction in classical monocyte subsets migrating to the peripheral blood (4, 27) Compared with AHI individuals, there was more CCR2 deficiency in the CHI individuals, which may be responsible for impaired monocyte migration in CHI individuals (28).