Bloom syndrome, also known as congenital telangiectatic erythema, is a rare genetic disorder that causes telangiectasia (permanent enlargement of blood vessels), photosensitivity, prenatal growth deficiency, varying degrees of immunodeficiency and increased susceptibility to many different types of cancer.
The syndrome is an inherited autosomal recessive disorder, which means both parents must carry the recessive gene in order for their child to be affected. If both parents are carriers, there is a 25% chance that the child will have the disorder, which appears within the first few months of life.
New York dermatologist David Bloom discovered the syndrome in 1954.
Since the syndrome was first recognized, there have been more than 170 case reports in the United States. While the disorder is extremely rare, it is most prevalent among individuals of Eastern European Ashkenazi ancestry. About one third of people with Bloom syndrome are of Ashkenazi Jewish descent, and the carrier rate for Ashkenazi Jews is about one percent. Cases of Bloom syndrome have also been reported in other countries, including Japan.
Mutations in the BLM gene (located on chromosome 15) cause Bloom syndrome. This gene provides instructions for the production of the Bloom (BLM) syndrome protein, which is a member of the DNA helicase family. The BLM protein helps stabilize the DNA when cells replicate. Mutations in the BLM gene reduce the protein's DNA helicase activity, resulting in chromosomal errors during replication. Consequently, individuals with Bloom syndrome have a higher frequency of both chromosome breakage and rearrangement than unaffected individuals.
Some researchers have suggested that individuals with Bloom syndrome overproduce the superoxide radical anion. These researchers claim that inefficient removal of peroxide might be the cause of chromosal damage and rearrangement.
Circulatory/Dermatologic: Telangiectatic erythema (dilation of blood vessels) appears as lesions on the skin or as butterfly-shaped patches of reddened skin on the face and other areas exposed to the sun. The sclera (white, protective, outer layer of the eyeball) blood vessels may also become dilated. Sun exposure worsens these symptoms.
Gastrointestinal: Newborns with Bloom syndrome are often disinterested in feeding. Regurgitation and vomiting is common during infancy. Patients should be evaluated for gastroesophageal reflux.
Immunodeficiency: Bloom syndrome causes decreased levels of immunoglobulin A and immunoglobulin M, which leads to recurrent respiratory and gastrointestinal tract infections.
Neoplasia (tumors): The chromosomal instability of Bloom syndrome patients causes an elevated cancer risk in affected individuals. Bloom syndrome patients are 150 to 300 times more likely to develop cancer compared to the general population. About 20% of Bloom syndrome patients develop malignancies. The cancers usually arise early in life, as individuals may be first diagnosed with cancer when they are about 25 years old.
Physical features: Usually the first physical symptom of Bloom syndrome is growth delay, which has a prenatal onset and persists throughout life. More than 50% of children with Bloom syndrome are significantly underdeveloped in physical stature until they are eight years old. Adults with Bloom syndrome have short stature. Bloom syndrome patients typically have long limbs, disproportionately large hands and feet and progressive contracture of hands and feet. Upper extremities are long in proportion to body length. Individuals with Bloom syndrome usually have a high-pitched voice, a long narrow face, small lower jaw and prominent nose and ears. Cheilitis (dry, cracked lips) with crusting or bleeding may also occur.
Bacterial respiratory tract infection is a common symptom of Bloom syndrome. If untreated, respiratory tract infections may progress to chronic bronchiectasis (chronic dilatation of the bronchi). Chronic pulmonary disease is the second most common cause of death in Bloom's syndrome.
Reproductive: Patients have primary hypogonadism (underactive sex organs). Women with the disorder usually experience menopause earlier than unaffected women.
Other symptoms may include learning disabilities, mental retardation and diabetes.
Prenatal diagnosis (at about 15-18 weeks gestation) is possible with amniocentesis. The amniotic fluid cell culture is evaluated to determine whether there is a high number of sister chromatid exchanges. Also, DNA analysis is expected to be available in the future.
A laboratory test called a chromosome study is used to diagnose patients with Bloom syndrome. The test, which is performed at the U.S. National Institutes of Health (NIH) and U.S. Armed Forces Institute of Pathology laboratories, evaluates chromosome stability, including sister chromatid exchanges, by looking at blood and skin cells.
In addition, immunoglobulin levels are evaluated. Individuals with Bloom syndrome have decreased levels immunoglobulin A and immunoglobulin M, with or without immunoglobulin G changes.
Currently, there is no specific treatment for the underlying cause of Bloom syndrome. However, avoiding sun exposure and using sunscreens may help reduce some of the cutaneous symptoms. Patients should also minimize exposure to known mutagens (agents that can potentially cause genetic mutations) like X-rays, ultraviolet light and various chemicals.
Growth hormone therapy has been used unsuccessfully to increase height in children with Bloom's syndrome. Also, there is some concern that the use of growth hormone may increase the risk for cancer later in life.
Bloom syndrome patients should be screened regularly for cancer. Surgical and/or oncology care may be necessary for the diagnosis and treatment of malignancies.
Strong scientific evidence
: The prescription drug All-Trans-Retinoic Acid (ATRA, Vesanoid©) is a vitamin A derivative that is an established treatment for acute promyelocytic leukemia and improves median survival in this disease. Treatment should be under strict medical supervision. Vitamin A supplements should not be used simultaneously with ATRA due to a risk of increased toxicity. If pregnant or breastfeeding, vitamin A should only be used within the recommended dietary allowance.
Good scientific evidence
There is recent evidence that supplementation with Lactobacillus casei may help reduce the recurrence of colorectal tumors in patients who have previously undergone surgery for colon cancer. Probiotics are generally regarded as safe for human consumption. Long-term consumption of probiotics is considered safe and well tolerated.
There is good evidence that psychotherapy can enhance cancer patients' quality of life by reducing emotional distress and aiding in coping with the stresses and challenges of cancer. Therapy may be supportive-expressive therapy, cognitive therapy or group therapy. Studies conflict on whether therapy improves self-esteem, death anxiety, self-satisfaction, etc. While some patients seek psychotherapy in hopes of extending survival, there is no conclusive evidence of effects on medical prognosis.
: Initial evidence has suggested that selenium supplementation reduces the risk of developing prostate cancer in men with normal baseline PSA (prostate specific antigen) levels, and low selenium blood levels. This is the subject of large well-designed studies, including the Nutritional Prevention of Cancer Trial (NPC), and the ongoing Selenium and Vitamin E Cancer Prevention Trial (SELECT), as well as prior population and case-control studies. There is evidence that low selenium levels are associated with an increased risk of prostate cancer, and several mechanisms for the beneficial effects of selenium supplementation have been suggested.
Since Bloom syndrome is a genetic disorder, no preventative measures can be taken against the disorder. However, prenatal diagnosis is possible with amniocentesis. Also, DNA analysis is expected to be available in the future.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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- Genetics Home Reference. http://ghr.nlm.nih.gov. Accessed March 16, 2007.
- Geneva Foundation for Medical Education and Research. www.gfmer.ch. Accessed March 16, 2007.
- Mount Sinai School of Medicine. www.mssm.edu. Accessed March 16, 2007.
- Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com. Copyright © 2007. Accessed March 16, 2007.
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