Alt. symbols: BS | RECQL3 | RECQ2

Approved name: BLM RecQ like helicase
Alt. names: Bloom syndrome, Bloom syndrome RecQ like helicase

Location: 15q26.1: 90717346 - 90816166 (+)
Gene type: protein_coding, 13 transcripts.

Scores: LoFtool: 0.959000 | pLI: 0.00000000 | LOEUF: 0.751

HGNC: 1058

NCBI: 641, RefSeq: NG_007272.1

Ensembl: ENSG00000197299.13

LRG_20 | Status: public

OMIM: 604610

Expression | ProteinAtlas

The BLM gene encodes the RECQL3 protein, a member of a protein family called RecQ helicases. Helicases are enzymes that bind to DNA and unwind the double helix so that DNA replication or DNA repair can take place. RecQ helicases are known as the "caretakers of the genome" because of their help in maintaining the DNA structure and integrity. During DNA replication, the copied DNA from each chromosome is arranged into two identical structures, called sister chromatids, which are attached to one another during the early stages of cell division. Sister chromatids occasionally exchange small sections of DNA during this time and research suggest that these exchanges may be a response to DNA damage during the copying process. The BLM protein helps to prevent excess sister chromatid exchanges and is also involved in other processes that help maintain the stability of the DNA during the replication process.

At least 70 distinct mutations in this gene have been identified in patients with Bloom syndrome, a rare disorder characterized by short stature, a skin rash that develops after sun exposure, and a greatly increased risk of cancer. One particular mutation (blmAsh mutation, c.2281delATCTGAinsTAGATTC) causes almost all cases of Bloom syndrome among people of Central and Eastern European (Ashkenazi) Jewish descent. The blmAsh mutation results in the production of an abnormally short, nonfunctional version of the BLM protein. However, there also many other truncating mutations known that also reduce the amount of functional BLM protein. The lack of functional BLM protein leads to an akteration of the frequency of sister chromatid exchange (about 10 times higher than average). In addition, chromosome breakage occurs more frequently in affected individuals. All of these changes are associated with gaps and breaks in the DNA that impair normal cell activities and cause the health problems associated with this condition. Without the BLM protein, the cell is less able to repair DNA damage caused by ultraviolet light, which results in increased sun sensitivity. Genetic changes that allow cells to divide in an uncontrolled way lead to the cancers that occur in people with Bloom syndrome. [Load More]