Bloom syndrome (BS, MIM# 210900) is a rare human recessive disorder associated with growth retardation, immunodeficiency and increased risk of malignancy at an early age. The causative gene for BS, BLM, which was mapped to the long arm of chromosome 15 (15q26.1), encodes a protein with 1417 amino acids. The BLM protein consists of seven domains, from the amino terminus poly-aspartate domain (PD1), poly-serine domain (PS), poly-aspartate domain (PD2), DEAH helicase domain (DEAH), RecQ helicase C-terminal domain (RecQCt), helicase and RNase D C-terminal domain (HRDC), and nuclear localization signals (NLS). The BLM protein shows similarity to sequences of RecQ subfamily of ATP-dependent DNA helicases, including RecQ, Sgs1, Rqh1, and the human RECQL and WRN proteins.

A program was developed for the submission of mutation and patient information to BLMbase. The registry was built according to the guidelines adopted in BTKbase. The aim is to provide information about the BS patients and their genetic defects in Internet by using World Wide Web. The BLMbase contains four main items: identification of the patient and mutation(s), reference either to published article(s) or a submitting physician, mutation information, and data related to disease and therapy. All the items are organized as fields, which are easily accessible. Protection of the patient's identity is assured in the registry.