Down syndrome is a genetic condition that is usually caused by an extra copy of the twenty-first chromosome. Most people have two copies of each chromosome, for a total of 46. People with Down syndrome have 3 copies of the 21st chromosome, making a total of 47. Down syndrome is also called Trisomy 21. According to Dr Dipanjana Datta, BGCI Level II certified Genetic Counsellor at Renew Healthcare, the down syndrome does not typically run in families and is not caused by anything either parent did or did not do. Some people can have “Translocation Down syndrome” or “Mosaic Down syndrome,” which are rare genetic variations of Down syndrome.
The journey of detecting and diagnosing Down syndrome is a delicate path marked by both medical expertise and compassionate care. From prenatal screenings to postnatal assessments, each step plays a crucial role in providing families with the information and support they need. Let us understand the causes, diagnosis, and prevention of this genetic disorder.
Down Syndrome: Causes
People with translocation Down syndrome can inherit the condition from an unaffected parent. The parent carries a rearrangement of genetic material between chromosome 21 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, as this translocation is passed to the next generation, it can become unbalanced. People who inherit an unbalanced translocation involving chromosome 21 may have extra genetic material from chromosome 21, which causes Down syndrome. Like trisomy 21, mosaic Down syndrome is not inherited. It occurs as a random event during cell division early in foetal development. As a result, some of the body's cells have the usual two copies of chromosome 21, and other cells have three copies of this chromosome
Down Syndrome: Diagnosis and Prevention
Prenatal screening tests, such as ultrasound and maternal serum screening, offer early indications of potential chromosomal abnormalities, including Down syndrome. These non-invasive procedures (NIPS) provide valuable insights, empowering parents to make informed decisions about their pregnancy.
In cases where prenatal screening suggests a heightened risk of Down syndrome, diagnostic tests, such as amniocentesis or chorionic villus sampling (CVS), offer definitive confirmation. While these procedures carry a small risk of complications, they provide invaluable clarity, enabling parents to prepare emotionally and practically for the road ahead.
People with balanced translocation who have a risk of having a child with Down Syndrome can opt for Preimplantation genetic testing {PGT ( SR)}, where embryos can be screened for the correct number of chromosomes, and the healthy embryo can be implanted. However, if the translocation is with Chr21 / Chr21, then the chance of trisomy 21 is 100 % and PGT is not useful.
Postnatally, clinical evaluations, including physical examinations and genetic testing, allow for the timely diagnosis of Down syndrome in newborns.
Down Syndrome: Early Diagnosis and Intervention
Early detection facilitates access to essential medical interventions, therapies, and support services, enhancing the overall quality of life for individuals with Down syndrome and their families. Down syndrome manifests as a neurodevelopmental disorder with mild to severe Intellectual Disability, It can also involve other organs like the Heart, gastrointestinal system, seizures, etc. However, proper management can extend the life of an affected individual to almost 60 years.
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