Why ATP shortage hits some functions first
ATP-dependent ion pumps, protein synthesis, and other high-cost processes compete for a limited ATP pool. When flux through a catabolic pathway drops, the tissue cannot sustain all of its ATP-consuming functions at once, so the most expensive and least essential ones are curtailed first. This ordering explains why early organ dysfunction often appears as loss of electrical stability or transport capacity rather than as immediate structural damage.
A muscle that cannot make enough ATP
A skeletal muscle that normally oxidizes a fuel through the affected pathway loses a large fraction of its ATP production when one step is blocked. The muscle can still contract briefly using stored phosphocreatine and glycolysis, but it fatigues quickly because it cannot regenerate ATP at the required rate. The symptom — rapid fatigue — is the observable end of the chain from missing enzyme to reduced flux to ATP shortage to loss of contractile work.
Dysfunction is downstream, not direct
Organ dysfunction in this setting is a consequence of ATP shortage in the tissue that depended on the pathway, not a direct effect of the missing enzyme. A tissue that does not use the pathway for energy may show no dysfunction even though it carries the same defect.