Bloom syndrome

A rare genetic disorder characterized by short stature and increased cancer risk

An individual with Bloom syndrome

Bloom syndrome metaphase cells exhibit frequent sister chromatid exchanges.

Bloom syndrome
Synonyms	Congenital telangiectatic erythema
Pronounce	N/A
Field	N/A
Symptoms	Growth deficiency, sun-sensitive skin rash, narrow face, high-pitched voice, immunodeficiency
Complications	Increased risk of cancer, diabetes, chronic lung disease, infertility in males
Onset	Present from birth
Duration	Lifelong
Types
Causes	Mutations in the BLM gene; autosomal recessive inheritance
Risks	Higher prevalence among Ashkenazi Jews
Diagnosis	Genetic testing, clinical evaluation, sister chromatid exchange test
Differential diagnosis	Fanconi anemia, Xeroderma pigmentosum, Ataxia telangiectasia
Prevention	Genetic counseling
Treatment	Symptomatic and supportive care, cancer screening and management
Medication	Antibiotics for infections, treatments for complications (e.g., insulin for diabetes)
Prognosis	Reduced life expectancy; many develop cancer at an early age
Frequency	Rare (fewer than 300 cases reported worldwide)
Deaths	Usually related to cancer or infections

Bloom syndrome has an autosomal recessive pattern of inheritance.

Bloom syndrome is a rare autosomal recessive genetic disorder characterized by short stature, a sun-sensitive skin rash, and an increased risk of cancer. It is caused by mutations in the BLM gene, which is responsible for encoding a protein that helps maintain the stability of DNA.

Genetics

Bloom syndrome is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected by the disorder. The BLM gene is located on chromosome 15, and mutations in this gene lead to a deficiency in the BLM protein, a type of helicase that is crucial for DNA repair and genomic stability.

Clinical Features

Individuals with Bloom syndrome typically present with several characteristic features:

• Short stature: Affected individuals are significantly shorter than their peers.
• Sun-sensitive skin rash: A distinctive rash often appears on the face, particularly on the cheeks and nose, after exposure to the sun.
• Increased cancer risk: There is a markedly increased risk of developing various types of cancer, often at a younger age than the general population.
• Immunodeficiency: Some individuals may have a weakened immune system, leading to increased susceptibility to infections.
• Facial features: Distinctive facial features may include a long, narrow face, prominent nose, and small lower jaw.

Diagnosis

Diagnosis of Bloom syndrome is typically based on clinical features and confirmed by genetic testing. The presence of increased sister chromatid exchange in cultured cells is a hallmark of the disorder. Genetic testing can identify mutations in the BLM gene to confirm the diagnosis.

Management

There is no cure for Bloom syndrome, and management focuses on monitoring and treating symptoms. Regular cancer screenings are essential due to the high risk of malignancies. Sun protection measures, such as wearing protective clothing and using sunscreen, are recommended to prevent skin damage. Supportive therapies may be needed for infections and other complications.

Prognosis

The prognosis for individuals with Bloom syndrome varies depending on the severity of symptoms and the development of cancer. With careful monitoring and management, some individuals can live into adulthood, although the risk of early death from cancer remains significant.

Related pages

• Genetic disorder
• DNA repair
• Cancer
• Autosomal recessive inheritance

External links

• Bloom syndrome at NLM Genetics Home Reference

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