Lesch-Nyhan syndrome: preventive control by prenatal diagnosis.

The Lesch-Nyhan syndrome was detected in a fetus at a time sufficiently early to allow termination of the pregnancy. The feasibility of a preventive program for control of a severe sex-linked neurological disease through prenatal diagnosis is thus demonstrated.

Hypoxanthine-guanine phosphoribosyltransferase deficiency: activity in normal, mutant, and heterozygote-cultured human skin fibroblasts.

Cultured skin fibroblasts from patients deficient for the enzyme hypoxanthine-guanine phosphoribosyltransferase (PRT) activity show very low but nevertheless significant levels of apparent PRT enzyme despite absence of detectable activity (<0.004% of normal) in erythrocytes of the same patients. In fibroblasts this mutant enzyme is more heat labile than the normal enzyme.

Substrate stabilization: genetically controlled reciprocal relationship of two human enzymes.

5-Phosphoribosyl-l-pyrophosphate, a substrate shared by adenine phosphoribosyltransferase and hypoxanthine-guanine phosphoribosyltransferase, accumulates in human erythrocytes lacking hypoxanthine-guanine phosphoribosyltransferase. 5-Phosphoribosyl-l-pyrophosphate added to purified adenine phosphoribosyltransferase stabilizes it against heat inactivation. The increased activity of adenine phosphoribosyltransferase seen in erythrocytes deficient in hypoxanthine-guanine phosphoribosyltransferase may result from substrate stabilization of this enzyme in vivo.

Cystine: compartmentalization within lysosomes in cystinotic leukocytes.

The large amount of cystine compartmentalized in cystinotic leukocytes cosediments in isopycnic sucrose density gradients with dense lysosomal particles, within which it is presumably contained. Such cystine appears to be primarily noncrystalline in these organelles.

Evidence for intergenic complementation in hybrid cells derived from two human diploid strains each carrying an X-linked mutation.

Two male diploid fibroblast strains, each carrying deficiency mutations at different X-linked loci (glucose-6-phosphate dehydrogenase and hypoxanthine-guanine-phosphoribosyltransferase) have been successfully hybridized. The resulting mononucleated hybrid cells have been shown to synthesize both normal gene products, indicating that both X chromosomes are functionally active in the hybrid cells. We believe this is the first reported example of intergenic complementation in fused human diploid cells.