Abstract
Down Syndrome (DS), or Trisomy 21 Syndrome, is one of the most common genetic diseases. It is a chromosomal abnormality caused by a duplication of chromosome 21. DS patients show the presence of a third copy (or a partial third copy) of chromosome 21 (trisomy), as result of meiotic errors. These patients suffer of many health problems, such as intellectual disability, congenital heart disease, duodenal stenosis, Alzheimer's disease, leukemia, immune system deficiencies, muscle hypotonia and motor disorders. About one in 1000 babies born each year are affected by DS. Alterations in the dosage of genes located on chromosome 21 (also called HSA21) are responsible for the DS phenotype. However, the molecular pathogenic mechanisms of DS triggering are still not understood; newest evidences suggest the involvement of epigenetic mechanisms. For obvious ethical reasons, studies performed on DS patients, as well as on human trisomic tissues are limited. Some authors have proposed mouse models of this syndrome. However, not all the features of the syndrome are represented. Stem cells are considered the future of molecular and regenerative medicine. Several types of stem cells could provide a valid approach to offer a potential treatment for some untreatable human diseases. Stem cells also represent a valid system to develop new cell-based drugs and/or a model to study molecular disease pathways. Among stem cell types, patient-derived induced pluripotent stem (iPS) cells offer some advantages for cell and tissue replacement, engineering and studying: self-renewal capacity, pluripotency and ease of accessibility to donor tissues. These cells can be reprogrammed into completely different cellular types. They are derived from adult somatic cells via reprogramming with ectopic expression of four transcription factors (Oct3/4, Sox2, c-Myc and Klf4; or, Oct3/4, Sox2, Nanog, and Lin28). By reprogramming cells from DS patients, it is possible to obtain new tissue with the same genetic background, offering a valuable tool for studying this genetic disease and to design customized patient-specific stem cell therapies.
Highlights
Down Syndrome (DS), or Trisomy 21 Syndrome, is one of the most common genetic diseases
The American College of Obstetricians and Gynecologists recommends providing the option of screening tests and diagnostic tests for DS to all pregnant women, regardless of the age[7]
This test is performed between 18 and 22 weeks of pregnancy. It has a higher risk of miscarriage than amniocentesis and chorionic villus sampling, so it is only recommended when results of other tests are unclear and the desired information cannot be obtained by any other method
Summary
Down Syndrome (DS), or Trisomy 21 Syndrome, is one of the most common genetic diseases. Mosaicism is the rarest type of DS which accounts for 2-4% of patients with DS[6] This form of genetic disorder is caused by problems after fertilization, during the phase where cells are dividing rapidly. The integrated screening test includes the features of the first trimester combined test with a maternal blood test to measure the levels of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A. In CVS, cells are taken from the placenta and used to analyze the fetal chromosomes This test is performed after 10 weeks of pregnancy and it has a higher risk of miscarriage than amniocentesis. The fetal blood is taken from a vein in the umbilical cord and examined for chromosomal defects This test is performed between 18 and 22 weeks of pregnancy. It has a higher risk of miscarriage than amniocentesis and chorionic villus sampling, so it is only recommended when results of other tests are unclear and the desired information cannot be obtained by any other method
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