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Bloom syndrome

Bloom disease, Bloom's Disease, Bloom's syndrome, BS, Bloom-Torre-Machacek syndrome, BLM, Growth deficiency, sun-sensitive, telangiectatic, hypo and hyperpigmented skin, predisposition to malignancy and chromosomal instability, BLS, Congenital Telangiectatic Erythema

Overview

Bloom syndrome is a disorder characterized by a significantly increased risk of cancer and various other features. It is a rare inherited condition characterized by photosensitivity, raised, red skin blotches, growth deficiency and increased susceptibility to infectious diseases and tumors. 

Symptoms - Bloom syndrome

Signs and symptoms include short stature; sun-sensitive skin changes on the face, hands and/or arms; a high-pitched voice; and distinctive facial features including a long, narrow face, small lower jaw, large nose and prominent ears. Some affected individuals may also have learning disabilities; an increased risk of diabetes; chronic obstructive pulmonary disease (COPD); and recurrent infections of the upper respiratory tract, ears, and lungs during infancy. Cancers may include any of those found in the general population, but develop much earlier in life in affected individuals. 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.

Causes - Bloom syndrome

Bloom syndrome is an autosomal recessive disorder associated with mutations in BLM gene encoding protein that belongs to the family of DNA helicases. It is characterized by predisposition to cancer, immunodeficiency, high sensitivity to UV and genomic instability of somatic cells.

Prevention - Bloom syndrome

Not supplied.

Diagnosis - Bloom syndrome

Bloom syndrome is diagnosed by either cytogenetic analysis or mutation testing. Cytogenetic analysis is used to detect if there is an increased amount of sister chromatid exchange in cells. Genetic testing can reveal if a person has mutations in the BLM gene, which are known to cause Bloom Syndrome. If an individual has a family history of Bloom syndrome, one of these two testing methods may be used to find out if the person has also inherited the condition. An unusually low birth weight and short height throughout childhood are suggestive of Bloom syndrome in an individual with an affected sibling.

Bloom syndrome is diagnosed by clinical features and can be confirmed by chromosome analysis. A greatly increased frequency of sister chromatid exchanges (SCEs) in cells exposed to bromodeoxyuridine (BUDR) is diagnostic; Bloom syndrome is the only disorder in which such evidence of hyper-recombination is known to occur. BLM is the only gene known to be mutated in Bloom syndrome. Molecular genetic testing for the common mutation, BLMAsh, is clinically available.

Prognosis - Bloom syndrome

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Treatment - Bloom syndrome

There is currently no cure for Bloom syndrome, so treatment is generally symptomatic and supportive. Because affected individuals are hypersensitive to DNA-damaging chemicals and ionizing radiation, standard cancer treatment plans often need to be adjusted for affected individuals. Changes may include reducing both the dosage and duration of the treatment; however, the cancers in affected individuals are often unusually responsive to treatment. The wide variety of types of cancer as well as the early development of tumors in affected individuals make life-long cancer surveillance significantly important. Additionally, it is recommended that individuals avoid sun exposure to the face, particularly in infancy and early childhood. Treatment of diabetes is typically the same as for individuals in the general population.

Resources - Bloom syndrome

NIH

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