Skip to content

#genomic instability

3 public questions tagged with this topic.

Bloom syndrome is associated with mutation in

Bloom syndrome is rare autosomal recessive disorder characterized by growth retardation, photosensitive facial rash, immunodeficiency, and markedly elevated sister chromatid exchanges leading to predisposition to many cancers. Molecular defect lies in BLM gene encoding RecQ helicase homologous to yeast Sgs1, possessing 3'→5' helicase activity. BLM together with Top3α and RMI1 forms dissolvasome that dissolves double Holliday junctions into non-crossovers. Deficiency causes accumulation of unresolved recombination intermediates resolved aberrantly by nucleases, producing excessive crossovers an

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 19: Bloom Syndrome and BLM Helicase Deficiency

RecQ helicase mediated dissolution prevents

Double Holliday junctions arising during DSBR can yield crossover if cleaved by resolvases such as Mus81 or Yen1. Somatic cells limit crossovers to avoid loss of heterozygosity and translocations. RecQ helicase family members including yeast Sgs1 and human BLM cooperate with topoisomerase IIIα and Rmi1/Rmi2 to dissolve double Holliday junctions. Helicase migration converges junctions into single hemicatenane structure decatenated by topoisomerase. This dissolution pathway produces exclusively non-crossover products, preventing interchange of flanking markers, while resolution by structure-spec

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 5: RecQ Helicase Dissolution Preventing Crossovers

Genomic instability in cancer cells leads to

Accumulation of mutations, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)