"Tertiary trisomy" - the extra chromosome is made up of copies of arms from two other chromosomes.Trisomies are sometimes characterised as "autosomal trisomies" (trisomies of the non-sex chromosomes) and "sex-chromosome trisomies." Autosomal trisomies are described by referencing the specific chromosome that has an extra copy. Thus, for example, the presence of an extra chromosome 21, which is found in Down syndrome, is called trisomy 21. Human trisomy
Trisomies can occur with any chromosome, but often result in miscarriage, rather than live birth. For example, Trisomy 16 is the most common trisomy in human pregnancies, occurring in more than 1% of pregnancies; only those pregnancies in which some normal cells occur in addition to the trisomic cells, or mosaic trisomy 16, survive. This condition, however, usually results in spontaneous miscarriage in the first trimester. The most common types of autosomal trisomy that survive to birth in humans are:

Trisomy 21 (Down syndrome)
Trisomy 18 (Edwards syndrome)
Trisomy 13 (Patau syndrome)
Trisomy 9
Trisomy 8 (Warkany syndrome 2)Of these, Trisomy 21 and Trisomy 18 are the most common. In rare cases, a fetus with Trisomy 13 can survive, giving rise to Patau syndrome. Autosomal trisomy can be associated with birth defects, intellectual disability and shortened life expectancy. Trisomy of sex chromosomes can also occur and include:
XXX (Triple X syndrome)
XXY (Klinefelter syndrome)
XYYCompared to trisomy of the autosomal chromosomes, trisomy of the sex chromosomes normally has less severe consequences. Individuals may show few or no symptoms and have a normal life expectancy. See also
Chromosome abnormalities
Aneuploidy
Karyotype
Sexual reproduction
Monosomy

References


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Low- to medium-quality evidence is also mounting for its use in bone and joint infections, including chronic osteomyelitis, although adverse effects are a significant concern when long-term use is necessary.In combination with other drugs, linezolid has been used to treat tuberculosis. The optimal dose for this purpose has not been established. In adults, daily and twice-daily dosing have been used to good effect. Many months of treatment are often required, and the rate of adverse effects is high regardless of dosage. There is not enough reliable evidence of efficacy and safety to support this indication as a routine use.Linezolid has been studied as an alternative to vancomycin in the treatment of febrile neutropenia in cancer patients when Gram-positive infection is suspected. It is also one of few antibiotics that diffuse into the vitreous humor, and may therefore be effective in treating endophthalmitis (inflammation of the inner linings and cavities of the eye) caused by susceptible bacteria. Again, there is little evidence for its use in this setting, as infectious endophthalmitis is treated widely and effectively with vancomycin injected directly into the eye. Infections of the central nervous system
In animal studies of meningitis caused by Streptococcus pneumoniae, linezolid was found to penetrate well into cerebrospinal fluid, but its effectiveness was inferior to that of other antibiotics. There does not appear to be enough high-quality evidence to support the routine use of linezolid to treat bacterial meningitis.