Handbook of Genetic Counseling/Bloom Syndrome-2

Bloom Syndrome (Also known as Bloom-Torre-Mackacek syndrome, BS, Levi's Type Dwarfism, Short Stature and Facial Telangiectasis)

Introduction

Acknowledge any prior contact with patient
Assess concerns and questions of the patient and his/her family
Assess knowledge of this condition and why the patient thinks he or she was referred to genetics
Patient's Medical History
Family Medical History and Pedigree

Mode of Inheritance: Autosomal recessive
Chromosome Location: BLM gene mutation at locus 15q26.1
Molecular Genetics: A cytogenetic diagnosis is made via increased rate of chromosome breakage and sister chromatid exchange

Since this is an inherited disorder, an affected parent has a 25% chance of passing on this syndrome to a child. Fifty percent of an affected parent's children will be carriers for this disease (carriers are usually asymptomatic).
Bloom syndrome is an incredibly rare disorder, with approximately 140 cases having been reported. It affects males slightly more than females. It is more prevalent in the Ashkenazi Jewish population, with an estimated carrier rate of 1 in 104.

Short stature with normal body proportions
Multiple small, dilated blood vessels on the face (facial telangiectasia) and on other light-exposed areas
Photosensitivity
Susceptibility to infections due to immune system defect
IUGR
Abnormally high-pitched voice
Dental anomalies
Prominent ears
Cysts at the base of the spine
Polydactyly
Acanthosis nigricans on parts of the body other than the face

As life progresses, patients with Bloom syndrome have an increased rate of malignant tumors, especially leukemia and squamous cell cancer of the skin. Diarrhea and vomiting are also common. Frequent infections and problems associated with short stature are also present.
Life expectancy is variable. Death is often a result of cancer.
Preterm labor has been shown to occur in women with Bloom syndrome. They also have a shorter reproductive span and reduced fertility. Men with Bloom syndrome are sterile.

Chromosome analysis is typically done to detect Bloom syndrome. Most often, chromosome fragility testing is performed to make a cytogenetic diagnosis.

Affected individuals should use sunscreen and should avoid direct contact with sunlight. Patients should have regular evaluations by dermatology, general medicine, genetics, and oncology. If an infection occurs, it should be treated aggressively with antibiotics.
Research on therapies is ongoing.
Psychosocial Issues
Affected patients and their family members may react initially to diagnosis with shock, frustration, denial, anger, fear, sadness, depression, guilt, and loss. The fact that patients with this syndrome require constant medical follow-up may be overwhelming for patients and families. Affected patients may have low self-esteem due to facial erythemia and their photosensitivity may make individuals (especially children) resentful of their condition, since it limits outdoor activities. Reproductive issues should also be considered with a genetic counselor, depending on the age of the patient when diagnosis is made.

NY Blood Center

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Telephone 1-800-362-4423

The information in this outline was last updated in 2002.

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