Which enzyme's deficiency is associated with an increased risk of thrombosis and atherosclerosis due to elevated homocysteine levels?

A Methionine synthase
B Cystathionine beta-synthase
C Methylenetetrahydrofolate reductase (MTHFR) ✓
D Dihydrofolate reductase

Explanation

MTHFR is involved in the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, which is necessary for the conversion of homocysteine to methionine. A deficiency in MTHFR can lead to elevated homocysteine levels, increasing the risk of thrombosis and atherosclerosis.

Source

_NEJM (New England Journal of Medicine)_
Enzymes in Disease Enzymology Hyperhomocysteinemia Hard MEDICAL Confidence: high