Bloom syndrome
Bloom syndrome (often abbreviated as BS in literature)[1] is a rare autosomal recessive genetic disorder characterized by short stature, predisposition to the development of cancer, and genomic instability. BS is caused by mutations in the BLM gene which is a member of the RecQ DNA helicase family. Mutations in genes encoding other members of this family, namely WRN and RECQL4, are associated with the clinical entities Werner syndrome and Rothmund–Thomson syndrome, respectively. More broadly, Bloom syndrome is a member of a class of clinical entities that are characterized by chromosomal instability, genomic instability, or both and by cancer predisposition.
Bloom syndrome
Cells from a person with Bloom syndrome exhibit a striking genomic instability that includes excessive crossovers between homologous chromosomes and sister chromatid exchanges (SCEs). The condition was discovered and first described by New York dermatologist Dr. David Bloom in 1954.[2]
Bloom syndrome has also appeared in the older literature as Bloom–Torre–Machacek syndrome.[3]
Diagnosis[edit]
Bloom syndrome is diagnosed using any of three tests - the presence of quadriradial (Qr, a four-armed chromatid interchange) in cultured blood lymphocytes, and/or the elevated levels of sister chromatid exchange in cells of any type, and/or the mutation in the BLM gene. The US Food and Drug Administration (FDA) announced on February 19, 2015, that they have authorized marketing of a direct-to-consumer genetic test from 23andMe.[25] The test is designed to identify healthy individuals who carry a gene that could cause Bloom Syndrome in their offspring.[8]
Treatment[edit]
Bloom syndrome has no specific treatment; however, avoiding sun exposure and using sunscreens can help prevent some of the cutaneous changes associated with photo-sensitivity. Efforts to minimize exposure to other known environmental mutagens are also advisable in multiple forms.