CONGENITAL ABNORMALITIES OF AMINO ACID TRANSPORT IN RENAL TUBULES
VARIETIES of syndromes have been described in which an abnormal amount of organic acid appears in the urine. In many of those syndromes which have been carefully studied, amino acids appear to constitute the major portion of organic acids. This probably is the result of the development of adequate methodology for the determination of amino acids. Nevertheless the author proposes classifying these diseases as organic acidurias, since it is his belief that there are organic acids, other than amino acid, present in the urine of these patients. Although the central theme of the Symposium of which this paper is a part is genetic defects, in the classification which is to be presented for consideration, some syndromes are included which are not genetic in origin. This is done for the purpose of completeness and to suggest the relationships between the syndromes with a genetic background and those in which the organic aciduria results from some nongenetically controlled aberrations. These syndromes may be roughly divided into two groups: Those in which the concentration of amino acids in the blood is elevated and those in which it is normal. The problem of classification of these syndromes has recently been reviewed in detail. In the group of syndromes with normal concentrations in the blood, further subdivision is necessary into four apparently different groups. In Table I are listed the diseases falling into these various categories. Among the diseases characterized by elevated concentration of organic acids in the blood, one may observe that only phenylpyruvic oligophrenia represents a congenital anomaly.