**Question:** Primary abnormality in sequence of events leading to DIC is-

A. Activation of coagulation cascade
B. Activation of fibrinolysis
C. Thrombocytopenia
D. Inflammation

**Core Concept:**
Dicarboxylic aciduria (DCA) is a rare genetic disorder caused by defects in mitochondrial enzymes involved in the citric acid cycle. These defects lead to accumulation of dicarboxylic acids and their intermediates in the body, resulting in abnormal coagulation, inflammation, and platelet dysfunction, ultimately causing disseminated intravascular coagulation (DIC).

**Why the Correct Answer is Right:**
The correct answer, A (activation of coagulation cascade), refers to the initial event in the process of DIC, where abnormal coagulation leads to the formation of fibrin clots in small blood vessels, causing microvascular obstruction and tissue damage. DIC is a life-threatening complication that occurs in severe illnesses like sepsis, trauma, or malignancy.

**Why Each Wrong Option is Incorrect:**
B (activation of fibrinolysis) is not the primary abnormality in DIC, as DIC is characterized by excessive activation of coagulation and fibrinolysis occurs as an adaptive response to counterbalance the excessive clotting.

C (Thrombocytopenia) is a consequence of DIC rather than its primary abnormality. Platelets are consumed in the clotting process, leading to thrombocytopenia.

D (Inflammation) is a consequence, rather than the primary cause, of DIC. Chronic inflammation can lead to tissue damage and release of damage-associated molecular patterns (DAMPs), which activate the coagulation cascade and contribute to the progression of DIC.

**Clinical Pearl:**
Understanding the pathophysiology of DIC is crucial for diagnosing and managing patients with severe illnesses. In clinical practice, recognizing the primary abnormality in DIC helps to identify patients at risk and initiate appropriate treatment and supportive care.