Can HAMP rs10421768 alter hepcidin expression and ferritin patterns during inflammation?

The HAMP gene, which encodes the primary iron-regulatory hormone hepcidin, plays a crucial role in managing systemic iron distribution. Genetic variation within its promoter region, specifically the rs10421768 (c.-582A>G) single nucleotide polymorphism, directly influences how the body regulates iron during immune challenges.

Mechanistic pathways of hepcidin regulation

• Reduced transcription: In vitro promoter studies demonstrate that the G allele of rs10421768 exhibits significantly lower promoter activity than the wild-type A allele.
• Impaired secretion: This transcriptional impairment results in reduced systemic hepcidin levels and compromises the body's ability to mount an inducible hepcidin response under stimulatory, infectious, or inflammatory stress.

Clinical and inflammatory implications

• State-dependent ferritin modulation: While the variant has negligible effects under baseline resting conditions in healthy populations, its impact is pronounced during inflammatory, infectious, or iron-overload states.
• Altered iron sequestration: Lower hepcidin expression in G allele carriers permits sustained iron export from intracellular stores. This alters the expected acute-phase iron sequestration, leading to modified systemic ferritin patterns and increased tissue iron deposition in conditions like β-thalassemia or sickle cell disease.
• Infection susceptibility: Clinically, the diminished inducible hepcidin response associated with the G allele directly correlates with an increased susceptibility to extrapulmonary tuberculosis.

Bottom line

• The HAMP rs10421768 G allele impairs inducible hepcidin expression, significantly altering systemic iron sequestration and modifying expected ferritin patterns during active inflammatory, infectious, or iron-overload states.