Bloomsyndromet

Bloomsyndromet, commonly known as Bloom syndrome, is a rare autosomal recessive genetic disorder caused by biallelic mutations in the BLM gene, which encodes a RecQ helicase involved in DNA repair and genome maintenance. The loss of BLM function leads to genomic instability and increased sensitivity to DNA damage.

Clinical features include severe growth retardation beginning before birth and persistent short stature, photosensitive skin changes, and poikiloderma—a mosaic of pigmented, atrophic, and telangiectatic skin on the face and sun-exposed areas. Immunodeficiency with recurrent infections and an elevated lifetime risk of malignancy are common.

Genetically, Bloom syndrome is inherited in an autosomal recessive manner. The BLM protein participates in homologous recombination and DNA replication fork maintenance. Its deficiency causes widespread chromosomal instability, including elevated rates of sister chromatid exchange, which is a diagnostic cytogenetic hallmark.

Diagnosis is based on clinical features and laboratory work, including a markedly increased rate of sister chromatid exchanges in cultured lymphocytes and confirmation by sequencing of the BLM gene.

Management is supportive and multidisciplinary. It emphasizes cancer surveillance, infection prevention and treatment, sun protection, nutrition and growth support, and genetic counseling for families. There is no cure, and prognosis is influenced by cancer risk and the severity of immune dysfunction.

Epidemiologically, Bloom syndrome is extremely rare but has a higher reported frequency in the Ashkenazi Jewish population due to a founder mutation. The condition requires ongoing medical follow-up throughout life.