Bloom syndrome

Bloom syndrome (also known as Bloom-Torre-Machacek syndrome or congenital telangiectatic erythema) is a rare autosomal recessive genetic disorder caused by biallelic pathogenic variants in the BLM gene (also called RECQL3), which encodes a RecQ family DNA helicase essential for maintaining genomic stability. The hallmark of the condition is marked chromosomal instability, with greatly increased rates of sister chromatid exchanges, which underlies the dramatically elevated predisposition to a wide spectrum of cancers occurring at unusually young ages. Clinical features typically manifest in infancy and include severe pre- and postnatal growth restriction resulting in proportionate short stature, a sun-sensitive telangiectatic erythema predominantly affecting the face (especially the butterfly area of the cheeks and nose), a high-pitched voice, and a characteristic narrow, long facial appearance with a small mandible and prominent nose and ears. Affected individuals frequently experience immunodeficiency with recurrent infections, insulin resistance or diabetes mellitus, and male infertility due to absent spermatogenesis. Females may have reduced fertility but can reproduce. Mild to moderate intellectual ability is typical, though intelligence is usually normal. The most serious complication is a markedly increased risk of malignancy, including leukemias, lymphomas, and various solid tumors, often occurring in childhood or early adulthood. There is no specific curative treatment for Bloom syndrome. Management is supportive and includes strict sun protection, growth monitoring, nutritional support, surveillance for diabetes, aggressive treatment of infections, and rigorous cancer surveillance protocols. Chemotherapy and radiation doses may need to be reduced due to the underlying chromosomal fragility. The Bloom Syndrome Registry, maintained since 1960, has been instrumental in characterizing the natural history of this condition.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Bloom syndrome