Bloom's Syndrome is, fortunately, a very rare inherited condition, with only 170 recorded cases worldwide to date. Bloom's Syndrome is classified as an autosomal1 recessive disease. As it is recessive, two copies of the defective gene are necessary before any effect is noticed. Therefore, one copy of a healthy gene will 'hide' the Bloom's gene. People with only one copy of the Bloom's gene are thus unwitting carriers. To suffer from the disease, a person must have two copies of the gene, a situation which arises when two carriers produce children. Interestingly, Bloom's Syndrome is more common amongst Ashkenazi Jews2, where almost 1% of the population is a carrier.
Bloom's Syndrome is caused by a genetic mutation on chromosome 15. This causes a change in the enzyme known as DNA ligase, the vital function of which is to link the components that make the DNA strand - without it, nothing could live. In sufferers, the gene mutations cause the enzyme to be defective, but not completely ineffective (or else the person would never have developed from zygote status!). The result of the less-than-perfect enzyme is that the sufferer's DNA is not repaired as well as it should be. DNA repair mechanisms operate constantly in higher organisms because DNA is continually damaged by radiation (such as from sunlight) and chemicals in the environment. The damaged repair mechanisms have their greatest effect in those parts of the body where rates of cell division are highest, and also make cancer more likely3.
Symptoms of Bloom's Syndrome
Small body size
Redness of the skin of the face, aggravated by sun exposure (erythema or butterfly rash)
Sub- or infertility (usually infertility in men and sub-fertility in women)
Immunodeficiency (specifically an increased number of respiratory tract and ear infections)
Increased susceptibility to all cancers
Prone to diabetes - about 10% of all people with Bloom's syndrome also have diabetes
High-pitched voice - obviously more noticeable in males
Carriers of Bloom's Syndrome do not exhibit symptoms.
Based in New York, the Bloom's Syndrome Registry researches and collates information about the condition.
The first known meeting between two sufferers occurred recently in the United States, between an American girl and an Australian boy.
More males than females have Bloom's, in a ratio of 4:3.
Many other genetic disorders are more common in Ashkenazi Jews than in other racial or ethnic groups. Examples of these include Tay-Sachs disease, Gaucher disease, Canavan disease, Niemann-Pick disease, Familial Dysautonomia, Fanconia Anemia, Torsion Dystonia and Mucolipidosis IV. Sadly many of these diseases affect children, and death occurs before puberty.
Bloom's Syndrome Registry
Bloom's Syndrome Registry
James L German III, MD
Professor, Departments of Pediatrics and Microbiology
Cornell University Medical College
1300 York Avenue
New York, NY 10021