What is the most common enzyme deficiency associated with homocystinuria?

What is the most common enzyme deficiency associated with homocystinuria?

• A. Cystathionine Beta-synthase
• B. Homocysteine Methyltransferase
• C. Serine Hydroxymethyltransferase
• D. Methylenetetrahydrofolate Reductase

Answer: (A)

Homocystinuria is primarily caused by a deficiency in cystathionine beta-synthase, the enzyme that plays a critical role in the metabolism of homocysteine. Under normal circumstances, this enzyme catalyzes the conversion of homocysteine to cystathionine, which is an important step in the transsulfuration pathway that also leads to the synthesis of cysteine from methionine. When there is a deficiency of cystathionine beta-synthase, homocysteine accumulates in the body, leading to various clinical manifestations, including connective tissue abnormalities, lens dislocation, and an increased risk of thromboembolic events. This enzyme deficiency is the most common cause of homocystinuria and is typically inherited in an autosomal recessive manner. The other enzymes listed, while involved in related metabolic pathways, do not constitute the primary cause of homocystinuria. Homocysteine methyltransferase, for instance, is involved in remethylating homocysteine to methionine, and deficiencies in this enzyme lead to a less common form of the condition. Serine hydroxymethyltransferase and methylenetetrahydrofolate reductase are related

Homocystinuria is primarily caused by a deficiency in cystathionine beta-synthase, the enzyme that plays a critical role in the metabolism of homocysteine. Under normal circumstances, this enzyme catalyzes the conversion of homocysteine to cystathionine, which is an important step in the transsulfuration pathway that also leads to the synthesis of cysteine from methionine.

When there is a deficiency of cystathionine beta-synthase, homocysteine accumulates in the body, leading to various clinical manifestations, including connective tissue abnormalities, lens dislocation, and an increased risk of thromboembolic events. This enzyme deficiency is the most common cause of homocystinuria and is typically inherited in an autosomal recessive manner.

The other enzymes listed, while involved in related metabolic pathways, do not constitute the primary cause of homocystinuria. Homocysteine methyltransferase, for instance, is involved in remethylating homocysteine to methionine, and deficiencies in this enzyme lead to a less common form of the condition. Serine hydroxymethyltransferase and methylenetetrahydrofolate reductase are related