Homocystinuria is classified as what type of aminoaciduria?

Homocystinuria is classified as a primary inherited overflow type of aminoaciduria because it arises from a genetic defect in the metabolism of homocysteine, typically due to deficiencies in specific enzymes like cystathionine beta-synthase. This condition leads to an accumulation of homocysteine and its metabolites in the body, which are then excreted in the urine in elevated amounts.

The term "overflow" refers to the fact that the amino acids are present in excess due to the metabolic block, resulting in their increased excretion. Because this condition is inherited, it falls within the primary category rather than being an acquired condition, which would be considered secondary.

Understanding the pathophysiology of homocystinuria as an inherited disorder is crucial for recognizing its implications for diagnosis, management, and genetic counseling.