Clinical Significance of Derangements of Tryptophan Metabolism

Tryptophan is an essential amino acid which was first isolated by Hopkins and Cole¹⁷in 1901. In recent years considerable attention has been drawn to a group of clinical syndromes which result from deficiencies in or deviations from the normal pathways of tryptophan metabolism. It is timely briefly to review the highlights of tryptophan metabolism, and to try to correlate the various syndromes related to its abnormalities. The dermatologist is particularly interested in the disturbances resulting from abnormal tryptophan metabolism, since they are commonly accompanied by skin manifestations which may help in establishing a correct diagnosis. Although considerable knowledge has been acquired on this subject in recent years, there are many areas still awaiting clarification and, therefore, it is very difficult to avoid entering the field of speculation. For these reasons, many of the statements presented in this study may not prove true in the future when more accurate