Disabled Macroautophagy Module

This module has no biochemical block, and that is a finding rather than an omission. Of the eleven hallmark-of-aging modules it is the only one where a literature search for an accessible human readout returns nothing usable, so the absence is recorded here instead of being left ambiguous or papered over with a marker that does not measure the hallmark. The obstacle is that autophagy is a flux, not a level. The standard readouts, LC3 and SQSTM1/p62, are steady-state abundances of proteins that are themselves consumed by the process, so a raised LC3-II is equally consistent with increased autophagosome formation and with blocked downstream degradation. Distinguishing the two requires either a lysosomal-inhibitor clamp or a tandem-fluorescent reporter, and both are available only in cell culture and animal models, not in a living human. The methodological literature is explicit that the individual assays are semiquantitative, that several proteins must be read together, and preferably over a time course. Two consequences worth stating for curators. First, do not import a single LC3 or p62 measurement into this module as a readout: without a flux clamp it does not have a direction, and `direction` is not optional guesswork. Second, this is a genuinely different gap from the ones recorded in loss_of_proteostasis and stem_cell_exhaustion. There the marker exists but is scoped to one protein or one compartment; here the quantity of interest is not measurable by any accessible means, so no amount of further curation will close it. Progress plausibly requires a tracer or imaging approach rather than a circulating analyte.

The macroautophagy pathway - autophagosome formation and lysosomal fusion, mediated by the conserved autophagy-related (ATG) genes - declines in capacity during normal and pathological aging. This reduced autophagic potential is the initiating lesion of the hallmark.

Autophagy selectively targets dysfunctional organelles, intracellular microbes, and pathogenic proteins for recycling, counteracting the age-associated accumulation of damaged organelles and proteins. When macroautophagy is disabled, this cytoplasmic quality-control and recycling function is lost - the central effector state that disease-specific autophagy lesions converge upon.

With cytoplasmic quality control disabled, damaged organelles and pathogenic proteins accumulate, producing degenerative changes and predisposing to age-related disease, especially neurodegenerative and inflammatory disorders. This is the conserved consequence of disabled macroautophagy; the specific clinical phenotype is supplied by the conforming disorder.