Discovery of Inborn Errors of Metabolism

Beginning with his study of a rare condition called alkaptonuria, which turns a patient's urine dark on exposure to air, the British physician Archibald Garrod traced the disorder through several affected families and found that it followed the same pattern of inheritance that Gregor Mendel had described for peas, a pattern now known as autosomal recessive. Garrod set out his findings in a 1902 paper and expanded them in his 1908 Croonian Lectures, proposing that alkaptonuria and similar conditions arose from a missing or faulty enzyme that a patient inherited, an idea he called an inborn error of metabolism. His concept of chemical individuality, that people differ from one another in their underlying biochemistry and not only in outward appearance, anticipated the biochemical understanding of genetics by several decades.