Diploid-triploid mosaicism

{{Infobox medical condition (new)

| name = Diploid-triploid mosaicism

| synonyms = Diploidy triploidy, 2n/3n mixoploidy, triploidy mosaicism, diploid triploid mosaic, DTM, mosaic triploid

| image = Two_kids_with_dtm_2014-07-16_21-09.jpg

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| caption = Two children with diploid-triploid mosaicism

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| field = Medical genetics

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Diploid-triploid mosaicism is a human chromosome disorder. Individuals with diploid-triploid syndrome have some cells with three copies of each chromosome for a total of 69 chromosomes (called triploid cells) and some cells with the usual 2 copies of each chromosome for a total of 46 chromosomes (called diploid cells).

Having two or more different cell types is called mosaicism. Diploid-triploid mosaicism can be associated with truncal obesity, body/facial asymmetry, weak muscle tone (hypotonia), delays in growth, mild differences in facial features, fusion or webbing between some of the fingers and/or toes (syndactyly) and irregularities in the skin pigmentation. Intellectual disabilities may be present but are highly variable from person to person ranging from mild to more severe. The chromosome disorder is usually not present in the blood; a skin biopsy, or analyzing cells in the urine is needed to detect the triploid cells.{{cite web|title=Diploid-triploid mosaicism|url=http://rarediseases.info.nih.gov/gard/10715/diploid-triploid-mosaicism/resources/1|publisher=Genetic and Rare Diseases Information Center (GARD)|date=22 March 2010|access-date=31 March 2014|archive-date=2 April 2014|archive-url=https://web.archive.org/web/20140402131856/http://rarediseases.info.nih.gov/gard/10715/diploid-triploid-mosaicism/resources/1|url-status=dead}}

Diploid-triploid individuals may have the karyotypes 46,XX/69,XXX or 46,XX/69,XXY. Individuals with 46,XX/69,XXY karyotype typically develop as phenotypically male, but may also exhibit disorders of sexual development. Almost all diploid-triploid individuals who are phenotypically female have the karyotype 46,XX/69,XXX, but a case has been reported where a 46,XX/69,XXY individual developed as phenotypically female.{{Cite journal |last=Oktem |first=Ozgur |last2=Paduch |first2=Darius A. |last3=Xu |first3=Kangpu |last4=Mielnik |first4=Anna |last5=Oktay |first5=Kutluk |date=March 2007 |title=Normal female phenotype and ovarian development despite the ovarian expression of the sex-determining region of Y chromosome (SRY) in a 46,XX/69,XXY diploid/triploid mosaic child conceived after in vitro fertilization-intracytoplasmic sperm injection |url=https://pubmed.ncbi.nlm.nih.gov/17164312/ |journal=The Journal of Clinical Endocrinology and Metabolism |volume=92 |issue=3 |pages=1008–1014 |doi=10.1210/jc.2006-1963 |issn=0021-972X |pmid=17164312}}

Triploidy is distinct from trisomy, in which only one chromosome exists in three pairs.{{cite web |date=2005 |title=Diploidly Triploidly |url=http://www.rarechromo.org/information/Other/Diploidy%20triploidy%20FTNP.pdf |url-status=dead |archiveurl=https://web.archive.org/web/20160304095026/http://www.rarechromo.org/information/Other/Diploidy%20triploidy%20FTNP.pdf |archivedate=2016-03-04 |access-date=31 March 2014 |work=Unique, Rare Chromosome Disorder Support Group |publisher=www.rarechromo.org}}