Genes on B chromosomes of vertebrates

Alexey I. Makunin, Polina V. Dementyeva, Alexander S. Graphodatsky, Vitaly T. Volobouev, Anna V. Kukekova, Vladimir A. Trifonov

Research output: Contribution to journalReview articlepeer-review


Background: There is a growing body of evidence that B chromosomes, once regarded as totally heterochromatic and genetically inert, harbor multiple segmental duplications containing clusters of ribosomal RNA genes, processed pseudogenes and protein-coding genes. Application of novel molecular approaches further supports complex composition and possible phenotypic effects of B chromosomes. Results: Here we review recent findings of gene-carrying genomic segments on B chromosomes from different vertebrate groups. We demonstrate that the genetic content of B chromosomes is highly heterogeneous and some B chromosomes contain multiple large duplications derived from various chromosomes of the standard karyotype. Although B chromosomes seem to be mostly homologous to each other within a species, their genetic content differs between species. There are indications that some genomic regions are more likely to be located on B chromosomes. Conclusions: The discovery of multiple autosomal genes on B chromosomes opens a new discussion about their possible effects ranging from sex determination to fitness and adaptation, their complex interactions with host genome and role in evolution.

Original languageEnglish (US)
Article number99
JournalMolecular Cytogenetics
Issue number1
StatePublished - 2014


  • Bchromosomes
  • Evolution of genomes
  • Proto-oncogenes
  • Segmental duplication
  • Vertebrates

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Genetics(clinical)
  • Biochemistry, medical


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