HUMAN BIOCHEMICAL GENETICS

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1.) Thirty-five children with cystinosis pre-renal transplant contribute data to a national protocol aimed at determining whether high dose cysteamine/phosphocysteamine is preferable to standard dose therapy. Cysteamine eyedrops (0.5%) are being used to dissolve corneal crystals in children over 2 years of age. Late complications of cystinosis are described, including exocrine and endocrine pancreatic insufficiency, myopathy, and ophthalmic and neurological involvement. One infant developed renal Fanconi syndrome despite cysteamine therapy from 14 days of age, and one cystinotic woman gave birth to a normal boy despite cystine crystals in her placenta. Carnitine therapy for patients with Fanconi syndrome continues to be pursued. 2.) Sialic acid transport across the lysosomal membrane was shown to be defective not only in Salla disease but also in infantile free sialic acid storage disease fibroblasts. Free sialic acid was shown to be filtered but not reabsorbed by the human kidney. 3.) Central demyelination and peripheral neuropathy were described in oculocerebrorenal syndrome of Lowe. It was found that heterozygotes can have nervous system involvement. A protocol was established to study the clinical and biochemical aspects of this X-linked disease. 4.) The lysosomal transport system for tyrosine and other neutral amino acids, discovered in rat FRTL-5 thyroid cell lysosomes, was shown to be TSH-responsive. So was a lysosomal transport system for monoiodotyrosine (MIT). The existence of this carrier, which may be identical to the tyrosine carrier, explains how thyroid cells can salvage thyroglobulin's iodine for reutilization. 5.) 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. Betaine therapy was shown not to improve bone density in pyridoxine-nonresponsive homocystinuria. 6.) A 2-year old boy with hepatic copper storage and aggregates in his fibroblasts helped demonstrate that Indian Childhood Cirrhosis is a genetic disease. 7.) Fibroblasts from patients with unknown lysosomal storage diseases are being screened to identify the stored material.