Which enzyme is involved in the pathogenesis of homocystinuria, a condition characterized by elevated levels of homocysteine in the blood?

A Cystathionine beta-synthase ✓
B Methionine synthase
C Homocysteine methyltransferase
D Serine hydroxymethyltransferase

Explanation

Homocystinuria is caused by a deficiency of cystathionine beta-synthase, which is necessary for the conversion of homocysteine to cystathionine. Elevated homocysteine levels can lead to vascular and neurological complications.

Source

OMIM (Online Mendelian Inheritance in Man)
Enzymes in Disease Biochemistry Amino Acid Metabolism Disorders Hard MEDICAL Confidence: high