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Bloom syndrome
Bloom's syndrome (BS) is a chromosomal instability syndrome characterized by photosensitivity & developmental anomalies.
Pathology:
1) defective cell-mediated immunity & increased susceptibility to infections are observed
2) leukemia occurs with higher frequency in BS patients
3) spontaneous sister chromatid exchange & chromosome aberrations are found in virtually all BS patients
4) reduced levels of DNA ligase are found in cells from patients with BS
Genetics:
1) autosomal recessive disorder
2) defects in the BLM helicase are the cause of Bloom syndrome
3) missense mutation in the gene for DNA ligase I is suggested
4) p53 mutations are common in transformed cells from BS patients
Clinical manifestations:
1) photosensitivity of prenatal onset
a) erythema & telangiectasia
-> butterfly distribution on the face
b) facial erythema develops during infancy following exposure to sunlight
c) a bullous eruption may appear on the lips
d) telangiectatic erythema may appear on the hands & forearms
2) cafe-au-lait spots, ichthyosis, acanthosis nigricans, & hypertrichosis are less constant cutaneous manifestations
3) developmental anomalies
a) dwarfism
b) defective dentition, prominent ears, pilonidal cysts, sacral dimples, syndactyly, polydactyly, clinodactyly of the 5th fingers, shortened lower extremities & club feet are additional inconstant features
c) proportionate pre- & postnatal growth deficiency
4) intellect is normal
Laboratory:
- BLM gene mutation analysis
- see ARUP consult [3]
Complications:
- predisposition to malignancy
General
bone marrow disease
chromosomal instability syndrome
progeroid syndrome
References
- Ponz de Leon Recent results in cancer res. 136:322 1994
- Nelson Textbook of Pediatrics, 14th ed., Behrman et al
(eds) WB Saunders, Philadelphia, 1992, pg 1651
- ARUP Consult: Jewish Genetic Disease
The Physician's Guide to Laboratory Test Selection & Interpretation
- Ashkenazi Jewish Genetic Diseases Carrier Screening Algorithm
https://arupconsult.com/algorithm/jewish-genetic-diseases-carrier-screening-algorithm
- Ashkenazi Jewish Genetic Diseases Panel
https://arupconsult.com/ati/ashkenazi-jewish-genetic-diseases-panel
Databases & Figures
OMIM 210900
Human Disorders of DNA Repair