A marker chromosome (mar) is a small fragment of a chromosome which generally cannot be identified without specialized genomic analysis due to the size of the fragment.[1] The significance of a marker is variable as it depends on what material is contained within the marker.[2] The large majority of these marker chromosomes are smaller than one of the smaller human chromosomes, chromosome 20, and by definition are termed small supernumerary marker chromosomes.[3]
Marker chromosomes occur sporadically about 70% of the time, with the remainder being inherited from a parent. About 50% of cases involve mosaicism, which affects the severity of the condition. The frequency is approximately 3-4 per 10,000 people, and 1 in 300 people with intellectual disability.[2]
Marker chromosomes typically occur in addition to the standard 46 chromosomes, making it a partial trisomy or tetrasomy supernumerary chromosome.[4] A marker can be composed of inactive genetic material and have little or no effect, or it can carry active genes and cause genetic conditions such as iso(12p), which is associated with Pallister-Killian syndrome, and iso(18p), which is associated with intellectual disability and syndromic facies.[5] Chromosome 15 has been observed to contribute to a high number of marker chromosomes, but the reason has not been determined.[1] The small supernumerary marker chromosome (sSMC) page contains examples of other birth defects, syndromes, and tumors that are associated with various types of sSMCs.
^ abNelson Textbook of Pediatrics, Chapter 81, 604-627 https://www.clinicalkey.com/#!/content/book/3-s2.0-B9781455775668000818?scrollTo=%23hl0003126
^Sun M, Zhang H, Li G, Guy CJ, Wang X, Lu X, Gong F, Lee J, Hassed S, Li S (September 2017). "Molecular characterization of 20 small supernumerary marker chromosome cases using array comparative genomic hybridization and fluorescence in situ hybridization". Scientific Reports. 7 (1): 10395. Bibcode:2017NatSR...710395S. doi:10.1038/s41598-017-10466-z. PMC 5583289. PMID 28871159.
^Jafari-Ghahfarokhi H, Moradi-Chaleshtori M, Liehr T, Hashemzadeh-Chaleshtori M, Teimori H, Ghasemi-Dehkordi P (2015). "Small supernumerary marker chromosomes and their correlation with specific syndromes". Advanced Biomedical Research. 4: 140. doi:10.4103/2277-9175.161542. PMC 4544121. PMID 26322288.
^Baldwin, Erin L.; May, Lorraine F.; Justice, April N.; Martin, Christa L.; Ledbetter, David H. (8 February 2008). "Mechanisms and Consequences of Small Supernumerary Marker Chromosomes: From Barbara McClintock to Modern Genetic-Counseling Issues". American Journal of Human Genetics. 82 (2): 398–410. doi:10.1016/j.ajhg.2007.10.013. PMC 2427313. PMID 18252220.
A markerchromosome (mar) is a small fragment of a chromosome which generally cannot be identified without specialized genomic analysis due to the size...
markerchromosome (sSMC) is an abnormal extra chromosome. It contains copies of parts of one or more normal chromosomes and like normal chromosomes is...
A chromosome is a package of DNA with part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated...
15, also called markerchromosome 15 syndrome, idic(15), partial tetrasomy 15q, or inverted duplication 15 (inv dup 15), is a chromosome abnormality in...
condition caused by an abnormal extra chromosome, i.e. a small supernumerary markerchromosome. This chromosome consists of the entire short arm and a...
X chromosome or are partially missing an X chromosome (sex chromosome monosomy). Most people have two sex chromosomes (XX or XY). The chromosomal abnormality...
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described...
homologs, which prevents de novo creation of wild-type chromosomes; and (3) carry dominant genetic markers, which can help identify rare recombinants and are...
on a chromosome. This linkage map may identify distances from other genes using (cM) centiMorgans as a unit of measurement. Co-dominant markers can be...
generation of linear yeast artificial chromosomes can be broken down into 6 main steps: Ligation of selectable marker into plasmid vector: this allows for...
with 0, 1, 2, 3 (etc.) B chromosomes. B chromosomes are distinct from markerchromosomes or additional copies of normal chromosomes as they occur in trisomies...
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination...
Xq28 is a chromosome band and genetic marker situated at the tip of the X chromosome which has been studied since at least 1980. The band contains three...
two copies of the p arm of chromosome 18. This extra chromosome is classified as a small supernumerary markerchromosome that forms de novo in a parent's...
protein. Small supernumerary markerchromosome (sSMCs) are extra chromosomes consisting of parts of virtually any other chromosome(s). By definition, they...
Small supernumerary markerchromosomes and giant rod chromosomes in osteosarcomas) Familial cases where the deletion of chromosome 13q14 inactivates the...
case. The small supernumerary markerchromosome in Tetrasomy 9p "Tetrasomy 9p" (PDF). rarechromo.org. Unique: Rare Chromosome Disorder Support Group. Retrieved...
between chromosomes 11 and 22 in the form of a der(22) chromosome. (This der(22) chromosome is classified as one of the small supernumerary marker chromosomes...
Supernumerary chromosome could refer to: B chromosome in some animals and plants Small supernumerary markerchromosome (sSMC) in humans This disambiguation...
Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million...
genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with developmental delays, mild to moderate...
used to isolate specific cell populations. B chromosomeChromosomal duplication Isochromosome Markerchromosome Polyploidy Rieger, R.; Michaelis, A.; Green...
Philadelphia of a small abnormal markerchromosome in patients with chronic myeloid leukemia—the first consistent chromosome abnormality detected in a human...
British Mandate of Palestine Small supernumerary markerchromosome (sSMC), an extra, 47th autosomal chromosome Supernumerary sexes (or supernumerary genders)...
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