Diagnosis and Testing
When can tetraploidy be diagnosed?
Most pregnancies carrying a tetraploid fetus will end in miscarriage within the first trimester. However, if the pregnancy continues, there may ultrasound findings indicative of physical birth defects in the fetus that may be apparent as early as near the end of the first trimester and throughout the remainder of the pregnancy. If a pregnant woman elected to undergo prenatal diagnostic procedures such as chorionic villus sampling (CVS), typically performed near the end of the first trimester of pregnancy, or amniocentesis, typically done starting around the 15th week of pregnancy, tetraploidy would be diagnosed.
- Bussamra, L.C., Drummond, C.L., Andrade, F.M., Tedesco, G., Britto, I.S. and Herbst, S.S. (2014), P02.27: Prenatal diagnosis of tetraploidy in a 13-week fetus with omphalocele and normal nucal translucency. Ultrasound Obstet Gynecol, 44: 196. doi: 10.1002/uog.14037
More Diagnosis and Testing Content
How can I find out if my baby has tetraploidy?
Prenatally, tetraploidy can be diagnosed by chorionic villus sampling (CVS) or amniocentesis. CVS, typically performed near the end of the first trimester of pregnancy, involves a needle biopsy of a small piece of the placenta. The placenta is formed from the same cells that form the baby following conception, and so usually the genetic information present in the placenta is the same as the baby. Amniocentesis, typically performed starting around the 15th week of pregnancy, involves withdrawing some amniotic fluid from the sac surrounding the baby and doing genetic testing on fetal skin cells that are present in the fluid.
After birth, tetraploidy would be diagnosed by genetic testing performed most typically on a blood sample from a baby, although saliva or other tissues may be used.
Families interested in more information about genetic testing during pregnancy or after birth may benefit from genetic counseling. The National Society of Genetic Counselors website includes a searchable "Find a Genetic Counselor" directory which can be used to locate genetic counselors throughout the United States and Canada.
Is there more than one test to diagnose tetraploidy after birth?
One genetic test able to diagnose tetraploidy is called a chromosome analysis, or karyotype. In a karyotype, the chromosomes in a cell are chemically treated in a specific way, and then the chromosomes are visualized, counted and arranged into their pairs. Either extra or missing whole chromosomes, or extra or missing pieces of a certain size, can be detected by karyotype analysis.
Additionally, a test called array comparative genomic hybridization, or chromosome microarray analysis, may also be used to diagnose tetraploidy in an individual. In chromosome microarray analysis, a sample is analyzed for areas of deletions (missing genetic material) and duplications (extra genetic material) all along the 23 pairs of chromosomes found in a cell. If an individual with tetraploidy had a chromosome microarray performed, the presence of four copies of all of the genetic material analyzed would indicate tetraploidy.
Karyotype analysis and chromosome microarray analysis are both available through many hospitals and commercial laboratories across the country. A medical geneticist or another physician familiar with this testing could order this genetic testing.
To find a genetic professional near you who can discuss genetic testing, visit the following two sites: A listing of medical geneticists can be found at the American College of Medical Geneticists website (www.acmg.net) and genetic counselors can be found on the National Society of Genetic Counselors website: www.nsgc.org.