Some trisomies cause few, if any, symptoms.
This article explains how trisomies occur and why some are more severe than others.
it also describes 10 different trisomies and the medical issues they can cause.
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What Causes a Trisomy?
Chromosomes are made up ofgenes, each of which carries coded information in the form ofDNA.
Of these, 22 pairs are calledautosomeswhich determine our unique biological and physical features.
The 23rd pair aresex chromosomesknown as an X and a Y chromosomewhich determine our biological sex.
From this point forward, the error will be repeated and repeated until embryogenesis is complete.
Consequences of a Trisomy
Different trisomies have different features.
In addition to causing birth defects, trisomies can causemiscarriage.
In fact, more than half of all miscarriages are thought to be resulting from a chromosomal defect.
With appropriate care, most can have a relatively normal life span.
Only around 5% of cases are due to translocation.
Compared to Down syndrome, Edwards syndrome is relatively uncommon, affecting one of every 5,000 births.
Only a few are resulting from translocation or mosaicism.
Symptoms are generally so severe that a baby with Patau syndrome rarely lives past the first month.
Patau syndrome is the third most common autosomal disorder among newborns after Down syndrome and Edwards syndrome.
Wakany syndrome is most commonly the result of mosaicism.
Babies born with mosaic trisomy 8 can survive, but this is rare.
Worldwide, mosaic trisomy 8 occurs in one out of every 25,000 to 50,000 live births.
It may also be the result of mosaicism.
Full trisomy 16 is incompatible with life.
Some may be otherwise healthy, but others may have congenital problems such as heart defects and developmental delays.
Trisomy 22
Most fetuses with full trisomy 22 are miscarried before the first trimester.
Trisomy 22is the second most common chromosomal cause of miscarriages.
Babies born with partial or mosaic trisomy 9 have a far greater chance of survival.
Other possible symptoms include smalltesticles, enlarged breasts (gynecomastia), and infertility.
Some people with Klinefelter syndrome may have learning disabilities, typically language-oriented, although intelligence is usually not affected.
Klinefelter syndrome is one of the more common trisomies, affecting one of every 500 or 1,000 babies.
The trisomy is not associated with physical features and often causes no medical symptoms.
Triple X syndrome is reported in one of every 1,000 live births.
Because it causes no overt symptoms, the number of actual cases is likely greater.
If anything, they can sometimes be taller than average.
Even so, the impairment tends to be mild.
Most adults with XYY syndrome have normal sexual development and are able to conceive children.
XYY syndrome is thought to affect one of every 1,000 live births.
Because there are few symptoms, it is thought that only one in eight cases is officially diagnosed.
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