Handbook of Genetic Counseling/Bloom Syndrome-2

From Wikibooks, open books for an open world
Jump to navigation Jump to search

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

Introduction[edit | edit source]

  • 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

Genetic Etiology[edit | edit source]

  • 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

Incidence and Carrier Frequency[edit | edit source]

  • 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.

Clinical Features[edit | edit source]

  • 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

Natural History[edit | edit source]

  • 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.

Testing[edit | edit source]

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

Treatment[edit | edit source]

  • 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.

Support Groups[edit | edit source]

  • Bloom's Syndrome Registry
NY Blood Center
310 East 67th Street
New York, NY 10021
Telephone 212-570-3075
  • National Foundation for Jewish Genetic Diseases
250 Park Avenue
Suite 1000
New York, NY 10017
Telephone 212-371-1030
  • MAGIC Foundation for Children's Growth
1327 North Harlem Avenue
Oak Park, IL 60302
Telephone 1-800-362-4423

References[edit | edit source]

  • Mendelian Inheritance in Man, POSSUM database, NORD database, GeneTests website

Notes[edit | edit source]

The information in this outline was last updated in 2002.