What is a trisomy 9?

General Discussion. Mosaic trisomy 9 is a rare chromosomal disorder in which the entire 9th chromosome appears three times (trisomy) rather than twice in some cells of the body. The term “mosaic” indicates that some cells contain the extra chromosome 9, while others have the typical chromosomal pair.

Is trisomy 9 inherited?

Mosaic trisomy 9 is usually not inherited . It often occurs sporadically as a random event during the formation of the reproductive cells (egg and sperm) or as the fertilized egg divides.

How long can you live with trisomy 9?

Trisomy 9 is extremely rare in live births. Only 0.1% of trisomy 9 conceptions will result in live birth with poor prognosis, with survival times ranging from mere minutes to 9 months after birth.

How is trisomy 9 Diagnosed?

Trisomy 9 is frequently diagnosed following a miscarriage, but it can also be detected during pregnancy by chorionic villus sampling (CVS) or amniocentesis. 7 Using placental tissue from CVS or fetal cells from amniocentesis, a doctor can order a picture of the baby’s chromosome (karyotype).

What are the different types of trisomy 9?

There are three types of trisomy 9: Full trisomy 9: All of the cells in the baby’s body and placenta have three copies of chromosome 9. Partial trisomy 9: There are two full copies of the ninth chromosome plus an additional partial copy.

What are the causes of trisomy 9p de novo?

Causes. In such de novo cases, the parents of the affected child usually have normal chromosomes and a relatively low risk of having another child with the chromosomal abnormality. In approximately 50% of cases, trisomy 9p may be due to a balanced chromosomal rearrangement in one of the parents.

What happens to cells with mosaic trisomy 9?

In people with mosaic trisomy 9, this attempt may be partly successful, leaving some cells with an extra chromosome 9 and some cells with the extra chromosome deleted (the usual chromosome number). This correction process is called trisomy rescue. [1] [2]

Are there two full copies of the ninth chromosome?

There are two full copies of the ninth chromosome plus an additional partial copy. Mosaic trisomy 9. Trisomy is present in some of the body’s cells while other cells have a normal set of chromosomes. Full trisomy 9 is nearly always fatal, with the vast majority of affected fetuses dying in the first trimester.