256 P. SOUPART 
6) Lesion of arginine metabolism. ALLAN et al.73 have described an abnormal ex- 
cretion of arginine-succinic acid” in children suffering from severe mental deficiency, 
probably hereditary in nature. 
7) Lesion of glycine metabolism. CHILDS ef al.** have discribed very recently a new 
disorder which can be listed here: idiopathic hyperglycinemia and glycinuria. The 
syndrome itself comprises growth and mental disturbances, anorexia, vomitings and 
convulsions. This clinical condition becomes worse when threonine, leucine or iso- 
leucine are fed. 
B. Aminoaciduria resulting from a congenital or acquired defect of the proximal con- 
voluted tubule 
I) Essential cystinuria. This condition is characterized by hyperexcretion of the 
“renal” type of cystine, lysine, arginine and ornithine exclusively, with an eventual 
formation of cystine stones in the urinary tract. No other amino acid is involved in 
this type of aminoaciduria. As plasma concentrations of the above amino acids 
are not elevated, the condition is thought to be due to a reabsorption defect of a 
congenital nature. After infusion of any amino acid of this group, excretion of 
all four amino acids is found to be increased. Since there are other occurrences of 
cystinuria not to be confused with the present condition, it is advisable to characterize 
it as “essential cystinuria’”’. 
2) De Tont-Debré-Fanconit syndrome. There is an aminoaciduria of the common 
type, involving all amino acids. All amino acids have increased clearances and the 
syndrome, still not fully understood, may be accompanied by cystinosis. In the later 
case, the condition is sometimes called “Lignac-Fanconi” since LiGNAac has been 
the first to describe cystinosis. It has been shown experimentally, that high doses 
of cystine produce albuminuria, gluciduria and a generalized cystinosis in dogs. 
3) Cystinosis. In this condition cystine accumulates in very large amounts in tissues 
and crystallizes there, forming important cystine deposits in the reticuloendothelial 
tissue of the liver, spleen, bone marrow, cornea and kidney, chiefly in the renal 
tubules. Plasma concentration of cystine is normal and there may be a_ hyper- 
cystinuria, although this does not seem to be the rule. It is still not known if eventual 
hypercystinuria is accompanied by hyperexcretion of lysine, arginine and ornithine, 
and the condition is therefore to be considered momentarily as distinct from essential 
cystinuria. Cystine deposits found in tissues suggest a metabolic block as the origin 
of the condition but on the other hand, when cystinuria is present in cystinosis, a 
renal tubular lesion is thought of. As cystinosis cases are scarce, correct classification 
of this condition must await further investigation. 
4) Heavy metal intoxication. Toxic effects of heavy metals have been considered to 
depress tubular reabsorption mechanisms, probably by means of enzyme inhibition. 
Accumulation of malic acid formed by the Krebs cycle has been claimed to depress 
the reabsorption mechanism, a situation which could result in a generalized amino- 
aciduria. 
9) Glycinuria in oxalic lithiasis. DE Vriks et al.83 have discribed hyperglycinuria in 
a patient with oxalic lithiasis. The condition seems to be a family one since it has 
been observed in 4 other members of the same family. 
6) Hyperaminoaciduria in lipoidic nephrosis. HooFT AND HERPOL®*, WOOLF AND 
References p. 261/262 
