Partial synonym is "neo-sex chromosomes" but this applies only to cases where neo-sex chromosomes have more than two members (i.e. not neo-XY but e.g. X1X2Y which can also be detailed as ♂X1X2Y/♀X1X1X2X2) and when multiple sex chromosomes include some novel part of the genome, previously autosomal (i.e. does not apply e.g. to fission of ancestral sex chromosomes as there is no "neo" part attached).
Textual definition
More than two sex chromosomes in the karyotype, usually manifested by different diploid chromosome number (2n) between males and females. They usually arise after chromosome rearrangements between original sex chromosomes and autosomes. A typical and most frequent case is a fusion between Y chromosome and autosome leading to X1X2Y (♂X1X2Y/♀X1X1X2X2) sex chromosome system where X1 represents the original X chromosome and X2 is a homolog to chromosome which fused to Y chromosome. These three members pair into trivalent during first meiotic division. Also, in this context, Y chromosome is designated as neo-Y and X2 chromosome as neo-X (neo-X2). In this case, males have three sex chromosomes (X1X2Y; Y remarkably large chromosome without homolog) while females have four sex chromosomes (two copies of X1 and X2). Multiple sex chromosomes do not generate male-vs-female differences in 2n e.g. in case if these have been generated by e.g. reciprocal translocation (e.g. X1X2Y1Y2 in males, X1X1X2X2 in females; more complex situations of multiple reciprocal translocations are also possible such as found in echina and platypus). Multiple sex chromosomes are usually monogenic (carrying a single master sex-determining gene or, more generally, a single sex-determining region) just as standard (XY, ZW) sex chromosome systems.
Suggested parent term
sex chromosome GO:0000803
ZW sex-determination system GSSO:000119
XY sex-determination system GSSO:000117
(Could be also UV sex-determination system which is not yet defined in OLS)
Attribution
0000-0003-4441-9615
Additional context
Exclude polygenic or polyfactorial sex determination (this is something different). Multiple sex chromosomes are usually monogenic but contain more chromosomes due to structural rearrangements (or as a consequence of aneuploidy). In case where "polygenic" means two sex chromosome systems in the transient state of sex chromosome turnover (i.e. previous sex chromosome system is still co-segregating with a new dominant sex chromosome system, such as e.g. in cichlids, e.g. Metriaclima pyrsonotus) I rather suggest to call it "complex sex chromosome system". The same may apply if there are populations with different sex chromosome systems and they mate and create different combinations of sex chromosome systems (such as e.g. in Glandirana rugosa, Xiphophorus maculatus, Xenopus tropicalis). Another interesting context is that multiple sex chromosomes are actually often instantly heteromorphic (cytologically distinguishable) but this is not the same process as heteromorphy generated by gradual accumulation of genetic divergence (deleterious mutations, repeats accumulations) due to recombination suppression.
Suggested literature:
Kitano, J., & Peichel, C. L. (2012). Turnover of sex chromosomes and speciation in fishes. Environmental biology of fishes, 94, 549-558. https://doi.org/10.1007/s10641-011-9853-8
Pokorná, M., Altmanová, M., & Kratochvíl, L. (2014). Multiple sex chromosomes in the light of female meiotic drive in amniote vertebrates. Chromosome Research, 22, 35-44. https://doi.org/10.1007/s10577-014-9403-2
Sember, A., Nguyen, P., Perez, M. F., Altmanová, M., Ráb, P., & Cioffi, M. de B. (2021). Multiple sex chromosomes in teleost fishes from a cytogenetic perspective: state of the art and future challenges. Philosophical Transactions of the Royal Society B: Biological Sciences, 376(1833), 20200098. https://doi.org/10.1098/rstb.2020.0098
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In which category is your new term request?
Preferred term label
multiple sex chromosomes
Synonyms
Partial synonym is "neo-sex chromosomes" but this applies only to cases where neo-sex chromosomes have more than two members (i.e. not neo-XY but e.g. X1X2Y which can also be detailed as ♂X1X2Y/♀X1X1X2X2) and when multiple sex chromosomes include some novel part of the genome, previously autosomal (i.e. does not apply e.g. to fission of ancestral sex chromosomes as there is no "neo" part attached).
Textual definition
More than two sex chromosomes in the karyotype, usually manifested by different diploid chromosome number (2n) between males and females. They usually arise after chromosome rearrangements between original sex chromosomes and autosomes. A typical and most frequent case is a fusion between Y chromosome and autosome leading to X1X2Y (♂X1X2Y/♀X1X1X2X2) sex chromosome system where X1 represents the original X chromosome and X2 is a homolog to chromosome which fused to Y chromosome. These three members pair into trivalent during first meiotic division. Also, in this context, Y chromosome is designated as neo-Y and X2 chromosome as neo-X (neo-X2). In this case, males have three sex chromosomes (X1X2Y; Y remarkably large chromosome without homolog) while females have four sex chromosomes (two copies of X1 and X2). Multiple sex chromosomes do not generate male-vs-female differences in 2n e.g. in case if these have been generated by e.g. reciprocal translocation (e.g. X1X2Y1Y2 in males, X1X1X2X2 in females; more complex situations of multiple reciprocal translocations are also possible such as found in echina and platypus). Multiple sex chromosomes are usually monogenic (carrying a single master sex-determining gene or, more generally, a single sex-determining region) just as standard (XY, ZW) sex chromosome systems.
Suggested parent term
sex chromosome GO:0000803 ZW sex-determination system GSSO:000119 XY sex-determination system GSSO:000117 (Could be also UV sex-determination system which is not yet defined in OLS)
Attribution
0000-0003-4441-9615
Additional context
Exclude polygenic or polyfactorial sex determination (this is something different). Multiple sex chromosomes are usually monogenic but contain more chromosomes due to structural rearrangements (or as a consequence of aneuploidy). In case where "polygenic" means two sex chromosome systems in the transient state of sex chromosome turnover (i.e. previous sex chromosome system is still co-segregating with a new dominant sex chromosome system, such as e.g. in cichlids, e.g. Metriaclima pyrsonotus) I rather suggest to call it "complex sex chromosome system". The same may apply if there are populations with different sex chromosome systems and they mate and create different combinations of sex chromosome systems (such as e.g. in Glandirana rugosa, Xiphophorus maculatus, Xenopus tropicalis). Another interesting context is that multiple sex chromosomes are actually often instantly heteromorphic (cytologically distinguishable) but this is not the same process as heteromorphy generated by gradual accumulation of genetic divergence (deleterious mutations, repeats accumulations) due to recombination suppression.
Suggested literature:
Kitano, J., & Peichel, C. L. (2012). Turnover of sex chromosomes and speciation in fishes. Environmental biology of fishes, 94, 549-558. https://doi.org/10.1007/s10641-011-9853-8
Pokorná, M., Altmanová, M., & Kratochvíl, L. (2014). Multiple sex chromosomes in the light of female meiotic drive in amniote vertebrates. Chromosome Research, 22, 35-44. https://doi.org/10.1007/s10577-014-9403-2
Pennell MW, Kirkpatrick M, Otto SP, et al (2015) Y Fuse? Sex Chromosome Fusions in Fishes and Reptiles. PLOS Genet 11:e1005237. https://doi.org/10.1371/journal.pgen.1005237
Charlesworth D, Charlesworth D (2021) The timing of genetic degeneration of sex chromosomes. https://doi.org/10.1098/rstb.2020.0093
Sember, A., Nguyen, P., Perez, M. F., Altmanová, M., Ráb, P., & Cioffi, M. de B. (2021). Multiple sex chromosomes in teleost fishes from a cytogenetic perspective: state of the art and future challenges. Philosophical Transactions of the Royal Society B: Biological Sciences, 376(1833), 20200098. https://doi.org/10.1098/rstb.2020.0098
Code of Conduct