Abstract:

Albinism is a genetic disorder characterized by impaired melanin synthesis or storage, with primary clinical manifestations including hypopigmentation of the skin, hair, and eyes. The conventional view holds that albinism is primarily caused by mutations in genes encoding melanogenic enzymes such as tyrosinase (TYR). Recent studies have revealed that melanosomes, a type of lysosome-related organelles, are the sites of melanin synthesis. The intraluminal ion homeostasis, particularly dynamic pH equilibrium, plays important roles in post-translational processing, subcellular localization, protein folding, and catalytic efficiency of TYR. A diverse array of ion channels and transporters embedded in the melanosomal membrane, including OCA2, SLC45A2, ClC-7/OSTM1, TPC2, and ATP7A, constitutes a sophisticated transmembrane electrochemical regulatory network. Through synergistic and antagonistic interactions with the vacuolar-type H⁺-ATPase (V-ATPase), these proteins dynamically modulate intraluminal pH, ion concentrations (e.g., Cl^-, Ca²⁺, Na⁺), and membrane potential across distinct melanosomal maturation stages, thereby creating a suitable microenvironment for melanin synthesis. This review systematically summarizes the molecular basis of melanosome ion homeostasis and proposes ion-homeostasis-targeted therapies and drug targets, providing new insights for a deeper understanding into albinism pathogenesis and a viable route for genotype-independent, universally applicable precision medicine.

Key words: albinism,  , melanosome, ion homeostasis,  , pH regulation