An infant with convulsions, mental retardation, delayed development, muscular and ligamentous asthenia, poor growth, and anemia was observed to have very high levels of plasma lysine and a massive lysinuria. Moderate urinary excesses of ornithine, ethanolamine, and γ-aminobutyric acid (GABA) were also present, while the usual derivatives of lysine were found in the urine in slightly increased amounts.
Lysine, an essential amino acid, is utilized extensively in protein synthesis. It is an important constituent of body proteins, particularly collagen, where—after incorporation—a portion of lysine is converted to hydroxylysine. Lysine not used in protein synthesis is metabolized along the pathway shown in Fig 1.
An increase of lysine in body fluids might occur in three ways: by impairment of the mechanism for deamination of lysine to α-keto-E-aminocaproic acid, by excess absorption of lysine from the bowel, or by reduced utilization of lysine in protein synthesis. With the first alternative, a reduction
WOODY NC. Hyperlysinemia. Am J Dis Child. 1964;108(5):543–553. doi:10.1001/archpedi.1964.02090010545015
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