HUMAN BIOCHEMICAL GENETICS

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1) Thirty children with cystinosis contributed data toward a national study demonstrating the efficacy of oral cysteamine therapy in enhancing growth and retardign renal failure. In addition, cysteamine eyedrops proved efficacious in removing cystine crystals from the corneas of young children with cystinosis. Late complications of cystinosis are described, including cerebral atrophy, diabetes mellitus, pancreatic exocrine dysfunction, muscle atrophy with parenchymal crystal accumulation, and ophthalmic involvement. One patient received a successful corneal transplant. Carnitine-deficient individuals with Fanconi syndrome continue to be treated with oral carnitine with some success in normalizing their muscle histology. 2) Sialic acid transport across the lysosomal membrane was shown to be defective not only in Salla disease but also an infantile free sialic acid stronge disease fibroblasts. Renal handling of free sialic acid and sialic acid metabolism in sialuria variants have been preliminarily investigated. 3) Lowe (oculocerebrorenal) syndrome fibroblasts manifested normal rates of proteoglycan synthesis and sulfation, but an increased activity of nucleotide pyrophosphatase. An HPLC method for separating proteoglycans was described. 4) The lysosomal transport system for tyrosine and other neural amino acids, discovered in rat FRTL-5 thyroid cell lysosomes was shown to be TSH-responsive. 5) Preliminary evidence shows that the FRTL-5 cells contain a lysosmal carrier for MIT, explaining how iodine is salvaged for reutilization by these cells. 6) Sulfur and methyl balance studies on an MAT--deficient patient demonstrated that, in vivo. S-adenosylmethionine regulates the partitioning of homocysteine between degradation to inorganic sulfate and remethylation to methionine.