Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency, also known as classic homocystinuria, is related to homocystinuria due to cystathionine beta-synthase deficiency and orthostatic intolerance, and has symptoms including seizures An important gene associated with Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency is CBS (Cystathionine Beta-Synthase). Affiliated tissues include eye and liver, and related phenotypes are intellectual disability and abnormality of amino acid metabolism