Bloom syndrome

Author: Vanessa Ngan, Staff Writer, 2007.

What is Bloom syndrome?

Bloom syndrome is a rare inherited condition characterised by:

The condition was first described by dermatologist Dr David Bloom in 1954 and is also known as congenital telangiectatic erythema.

What causes Bloom syndrome and who gets it?

Bloom syndrome is an autosomal recessive inherited disorder, which means that two abnormal Bloom syndrome genes are needed for the disease to be apparent (one from each parent). If a person has one affected gene, he or she is called a carrier of Bloom Syndrome and does not manifest symptoms of the disease. If both parents are carriers, there is a 1 in 4 chance of having an affected child with each pregnancy. Recessive diseases are often consanguineous (eg, cousin marriages).

The gene for Bloom syndrome, BLM, is located on chromosome 15 (gene locus is band 15q26.1). Mutations in this gene cause errors in the copying process during DNA replication and result in a higher number of chromosome breakages and rearrangements/sister chromatid exchanges. The result is abnormalities in the protein RecQL3, which lead to the signs and symptoms of Bloom syndrome.

Bloom syndrome is more common in eastern European Ashkenazi Jews. At least 1 in 100 Ashkenazi Jews is a carrier of the disease. It appears to be slightly more common in males than females.

What are the signs and symptoms of Bloom syndrome?

Bloom syndrome is apparent from birth with affected newborns being unusually small. Most parents seek medical help when the infant does not grow normally. Over 50% of children are significantly underdeveloped in physical stature until age 8 years, and most fail to reach 1.5 metres (5 feet) in adulthood.

Other features of Bloom syndrome become apparent as the child grows older. These include:

What is the treatment for Bloom syndrome?

Because it is a genetic disorder, no cure is available. Genetic counselling may be appropriate for affected individuals and carriers (their parents and siblings). A genetic test to identify the mutation is available in some regions.

Treatment is primarily preventative.

What is the outcome for Bloom syndrome?

Death often occurs in the second or third decade, commonly from cancer.

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