The gene responsible in this disorder, blm, was mapped to 15q26.1 and its product was found to encode aRecQ DNA helicase. It is involved in DNA replication and repair. Bloom syndrome is an autosomal recessive disorder. The predominant mutation is referred to as “blmAsh”, a 6-bp deletion and 7-bp insertion at nucleotide position 2281.
- Affects approximately 1 in 48,000 Ashkenazi Jewish individuals
- It is estimated that 1 in 110 of those who are of Jewish ancestry are carriers
- Small stature, immunodeficiency, chromosomal instability, and a predisposition to different types of cancer and infection
- Photosensitivity and elevated dark red blotches on the skin
- Intelligence is typically unaffected, although mild mental retardation has been reported in some cases
- Mean age of death is 27 years of age and is usually related to cancer
- Men with Bloom syndrome are sterile
- Women have reduced fertility and shortened reproductive span
- Bloom syndrome individuals are characterized with having a long, narrow face with a prominent nose (due to lack of subcutaneous fat)
- Telangiectatic erythema of the face (broken spider veins and redness of the skin)
- Cheilitis (swelling of the lips)
- Relatively large protruding ears
There is currently no treatment for the underlying cause of Bloom’s syndrome. Preventative measures should be taken, such as increased surveillance for infection, cancer and decreased exposure to sunlight and X-rays. Bone marrow transplant is a possibility.