2060 R. G. WESTALL 
HEREDITARY DISORDERS OF AMINO ACID METABOLISM 
A number of hereditary diseases have been described which exhibit an increased 
aminoaciduria. These diseases will not be discussed from the standpoint of genetics 
or of more than passing references to certain clinical features but they will be used as 
instances of the various ways that the handling of the amino acids by the body may 
be altered. 
The aminoacidurias have been divided into two groups**: the renal type where 

TYR 

THR 
CYS-A 
PRO HIS 

CLU-NH, 
ARG 
LYS 
Fig. 7. A paper chromatogram of the urine from a child with cystinosis. 
the amino acid pattern of the blood plasma is normal and the aminoaciduria is due 
to a defect in renal tubular reabsorption which may be selective for certain amino 
acids only or which may be more generalized due to more widespread damage to the 
kidney. The second type is known as the “overflow” aminoaciduria. Here the kidney 
function is normal and the increased excretion is due to a high plasma concentration 
of certain amino acids. These may be normal constituents, for which there is a low 
renal clearance, or they may be amino acids which are not usually found in plasma 
and for which the renal clearance is high. This latter sub-type has been called a “no 
threshold”-aminoaciduria™®. 
References p. 217/219 
