Bloom syndrome

Bloom syndrome is a rare inherited disorder caused by pathogenic variants in BLM. It is marked by short stature, sun-sensitive skin changes, immune problems, and greatly increased cancer risk.

BLM: BLM is a DNA helicase that helps resolve problematic DNA structures during replication and repair. Pathogenic variants in this gene cause Bloom syndrome by impairing genome maintenance.
Autosomal recessive inheritance: Autosomal recessive inheritance occurs when disease results from pathogenic variants in both copies of an autosomal gene. Bloom syndrome usually requires a disease-causing BLM variant from each parent.
Molecular genetic testing: Molecular genetic testing identifies disease-associated changes in DNA, often in a specific gene or gene panel. Finding pathogenic variants in both BLM copies can confirm Bloom syndrome.
Poikiloderma: Poikiloderma is a skin pattern combining pigmentation changes, small visible blood vessels, and thinning or atrophy. Sun-exposed skin in Bloom syndrome often develops this distinctive pattern during childhood.
DNA helicase: A DNA helicase is an enzyme that separates or rearranges DNA strands using energy from ATP. BLM belongs to this enzyme family, whose strand-processing activity supports faithful DNA replication.
DNA repair: DNA repair comprises cellular processes that detect and correct damage or errors in genetic material. Bloom syndrome arises from impairment of a DNA repair and replication-maintenance protein.
Cancer surveillance: Cancer surveillance uses scheduled examinations or tests to detect cancer early in people at elevated risk. The markedly increased and early-onset cancer risk calls for individualized, ongoing monitoring.
Short stature: Short stature is height substantially below the expected range for age, sex, and population. Prenatal and postnatal growth restriction is a defining feature of Bloom syndrome.
Homologous recombination: Homologous recombination is a DNA repair process that uses a matching sequence as a template. BLM helps regulate this repair pathway and limits exchanges between matching chromosomes.
Genome instability: Genome instability is an increased rate of mutations, chromosome rearrangements, or other changes in genetic material. It connects BLM dysfunction to the syndrome’s broad cellular and clinical consequences.

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