Homozygous BLM mutations cause a rare autosomal recessive inherited disorder “Bloom Syndrome” that is characterized by chromosomal instability, immunodeficiency, and a predisposition to different types of malignancies, including breast and colon cancers (de Voer et al., 2015; Kluzniak et al., 2019). The gene discussed is BLM; the disease is Bloom syndrome.