Clonal origin of chronic myelocytic leukemia in man

Gene loss in human teratomas

If benign cystic teratomas (dermoid cysts) of the ovary arise from a germ cell that has undergone meiosis, they should be missing genes which are present in the person. Three independently segregating allelic isozymes in 11 benign cystic teratomas of the human female ovary were compared with normal tissue of the same case. Dermoid cysts from persons heterozygous for these isozymes are frequently homozygous for that particular gene product. One of two dermoid cysts is homozygous for glucose-6-phosphate dehydrogenase, two of four tumors are homozygous for phosphoglucomutase at the PGM(1) locus, and two (or more) of eight tumors are homozygous for phosphoglucomutase at the PGM(3) locus in women heterozygous for these allelic isozymes. These findings are consistent with the hypothesis that these tumors arise from a germ cell which has undergone meiosis with varying degrees of crossing-over.

6-phosphogluconate dehydrogenase: hemizygous manifestation in a patient with leukemia

In a study of 41 patients with chronic myelocytic leukemia, two were found to have the 6-phosphogluconate dehydrogenase heterozygous phenotype A-B, and two had the phenotype characteristic of Pd(B) homozygosity. Since one of the two with Pd(B) homozygosity was the mother of two children with the A phenotype, it was presumed that she carried a Pd(A) gene not expressed in her blood cells. his was confirmed by electrophoretic analysis of her fibroblasts, which had the A-B phenotypic pattern. Gene deletion is considered to be the most likely explanation.