The ORC5L gene encoding a subunit of the human origin recognition complex (ORC) maps to chromosome band 7q22, a region frequently deleted in adult acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Because of its localization within a region that is commonly deleted in patients with myeloid malignancies and because of the implication of its protein product in cell cycle control (DNA replication) and regulation of gene expression (transcriptional silencing), ORC5L appeared to be a candidate tumor suppressor gene for myeloid disorders associated with 7q22 deletions. Polymerase chain reaction amplification and sequencing analysis of the coding region of the remaining ORC5L allele has not revealed any mutations in nine patients with AML or MDS exhibiting 7q22 deletions. Allelic expression analysis indicates that ORC5L is not imprinted. These data suggest that ORC5L does not function as a tumor suppressor in patients with myeloid neoplasms.