Bloom Syndrome

Bloom syndrome is an inherited disorder characterized by a high frequency of breaks and rearrangements in an affected person's chromosomes. People with Bloom syndrome are much smaller than average, and often have a high-pitched voice and characteristic facial features including a long, narrow face; small lower jaw; and prominent nose and ears. They tend to develop pigmentation changes and dilated blood vessels in the skin, particularly in response to sun exposure. These changes often appear as a butterfly-shaped patch of reddened skin on the face. The skin changes may also affect the hands and arms.

Other features of the disorder may include learning disabilities, mental retardation, chronic lung problems, diabetes, and immune deficiency that leads to recurrent pneumonia and ear infections. Men with Bloom syndrome usually do not produce sperm, and as a result are unable to father children (infertile). Women with the disorder generally experience menopause earlier than usual.

Bloom syndrome confers a 150-300 times increased risk of cancer as compared to the general population, causing life expectancy to be shortened. Affected individuals develop the full range of cancers found in the general population, but the cancers arise unusually early in life. People with Bloom syndrome may be first diagnosed with cancer at about 25 years old.

Bloom syndrome is a very rare disorder in most populations but is more common in people of Central and Eastern European (Ashkenazi) Jewish background, among whom 1 in 48,000 are affected. Approximately one third of people with Bloom syndrome are of Ashkenazi Jewish descent, and approximately 1 in 104 people with Ashkenazi Jewish ancestry is a carrier of Bloom syndrome.

DNA Direct offers Ashkenazi Jewish Carrier Screening for $262 to $1219 depending on the tests ordered. Individuals with Bloom syndrome have two copies of a gene mutation, one copy inherited from each parent. Neither gene in the pair is working correctly, which causes the symptoms of the disease. A carrier of Bloom syndrome is a person who has a mutation in one gene of the pair. Carriers are unaffected with the disease because the properly working gene is able to compensate for the gene that contains the mutation, but they are at risk of passing the gene mutation on to their children.