Detection of the carrier state for an X-linked disorder, the Lesch-Nyhan syndrome, by the use of lymphocyte cloning

Using a limiting dilution technique, we found that the frequency of thioguanine resistant (TG^R) lymphocyte clones was less than 5.0x10^-5 in 14 normal individuals, between 9.0x10^-3 and 8.9x10^-2 in seven heterozygotes for Lesch-Nyhan syndrome, and 0.88 and 0.87 in two hemizygotes. TG^R clones from heterozygotes were expanded and had the hemizygote phenotype as evidenced by low hypoxanthine incorporation and severely deficient hypoxanthine-guanine-phosphoribosyl-transferase activity. Enumeration of TG^R lymphocyte clones provides a simple technique for detection of heterozygosity for Lesch-Nyan syndrome. A similar approach using lymphocyte cloning may be suitable for detection of the carrier state for other X-linked disorders.