Which of the following is a DNA repair defect?

Bloom syndrome (often abbreted as BS in literature), also known as Bloom-Torre-Machacek syndrome, is a rare autosomal disorder characterized by sho stature, predisposition to the development of cancer and genomic instability. BS is caused by mutations in the BLM gene leading to mutated DNA helicase protein formation. Cells from a person with Bloom syndrome exhibit a striking genomic instability that includes excessive crossovers between homologous chromosomes and sister chromatid exchanges (SCEs). Autosomal Recessive Syndromes of Defective DNA Repair Xeroderma pigmentosum Ataxia-telangiectasia Bloom syndrome Fanconi anemia Ref Robbins 9/e pg 172