garrod's tetrad garrod's tetrad in medicine, garrod's tetrad is a term named for british physician archibald garrod, who introduced the phrase "inborn errors of metabolism" in a lecture in 1908. the tetrad comprises four inherited metabolic diseases: albinism, alkaptonuria, cystinuria, and pentosuria. trick to learn paca. ( pentosuria, albinism, cystinuria, alkaptonuria.