A trial of isolating the novel genes on 21q11-21 to elucidate the gene responsible for transient abnormal myelopoiesis

Abstract

    Transient abnormal myelopoiesis (TAM) is a leukemoid reaction which is found in about 10% of cases with Down's syndrome during the neonatal period. While in most of the cases, it resolves spontaneously without any antileukemic therapy, 20-30% of cases develop acute megakaryoblastic leukemia (AMKL) after the remission. It is important to isolate the responsible gene for TAM, because it may lead to elucidation of the process of oncogenesis in hematopoietic cells. Possible candidate location has been reported to be in the pericentric region of 21q. In this report, we tried to identify novel genes in the region of 21q11-21 and isolated 13 independent clones by the screening of cDNA library of CMK11-5 cells, derived from AMKL in Down's syndrome. Analysis of the clones revealed that the 9 clones of them were derived from the same transcript coded in 21q11-21. The clone #64, one of the 9 clones was the full length of the gene and we could indicate the exon-intron structure of the novel gene. The predictive amino acid sequences from the gene had no homology to known proteins.