DOCTOR-SPEAK—Down Syndrome by Dr Manjeet Mehta
Dr Manjeet Mehta PhD (Human Genetics), Fellowship (Genetic Medicine)
Consultant, Genetics & Molecular Medicine
Kokilaben Dhirubhai Ambani Hospital & Medical Res. Inst., Mumbai (Prev.)
Breach Candy Hospital, Mumbai; Surya Hospital, Mumbai (visiting)
Rainbow Global Hospital, Agra; Tyagi Multi Speciality Hospital, Lucknow
Director, Genetic World, Mumbai; Director, NeoGenetic Labs, New Delhi
Committee member – Indian Society for Prenatal Diagnosis & Therapy
Executive – Indian Society for Assisted Reproduction
Member – Technical Advisory Board, International Journal of Molecular & Immuno Oncology
What is Down syndrome (DS)? Is it hereditary? If a couple has one child with DS, what are the chances of having another one with this syndrome? Is it preventable?
Down syndrome is a condition caused due to the presence of one extra chromosome in our cells. Such people have three copies of chromosome number 21 instead of the normal two. It manifests with a typical clinical presentation. It could be de novo (due to some error in fertilization) or may be inherited if one of the parents is carrier of a Robertsonian translocation (when two smaller chromosomes are fused and travel as one during inheritance). If the cause of the extra chromosome is one of the parents being a carrier, then subsequent pregnancies have a chance of bearing child with Down syndrome. However, if the child with Down syndrome has three ‘free’ copies of chromosome 21, the chances of having another child with Down syndrome is very low (same as background population risk). This condition is lifelong; symptoms can be treated, but the condition cannot be reversed. The only way to prevent the birth of a baby with Down syndrome is by appropriate screening during pregnancy.
How is DS diagnosed? How much do the antenatal screening and diagnostic tests for DS approximately cost?
In a newborn child, a few clinical features give clear indication of Down syndrome. They are hypotonia (decreased muscle tone) and characteristic facial features like macroglossia (protruding tongue), mongoloid eyes, and simian crease (single transverse crease running across palm). In growing children, we observe developmental delays in their milestones, physical growth delays, and some extent of intellectual disability.
During pregnancy most of the women are asked to undergo a screening test i.e., dual marker in first trimester or quad marker in second trimester. These tests are for levels of some biochemical enzymes — alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and inhibin-A in the mother’s blood and give an indication of whether the fetus may be affected with Down syndrome (and some other conditions). A more sensitive test recently available is NIPT (noninvasive prenatal testing). However, these are all screening tests that give the risk of Down syndrome in the fetus. Additionally, some sonography measurements and certain ultrasound markers give an indication. Finally, for a confirmatory test, we have to sample some fetal tissue (day care procedure) and test it in the laboratory.
The approximate costs of the tests are:
Double Marker: Rs 1,800 – 2,400/-
Sonography: Rs 2,000/-
Quad Marker: Rs 2,000 – 2,600/-
NIPT: Rs 22,000 – 26,000/-
Invasive Amniocentesis Procedure: Rs 5,000 – 7,000/-
Lab tests: Rs 8,000 – 12,000/-
Can a person with DS lead a normal life like any other person, e.g., study in school/college, do a job, get married, raise children, etc.?
As Down syndrome involves several aberrations, each one would have to be examined and addressed individually. Children with Down syndrome may be slow learners. The extent of mental impairment varies. They may require special schooling. Some of them may require speech therapy. Today, with all these options available, the life span has gone up. People with Down syndrome are surviving for longer, leading healthy lives, and getting married and having children.
What, in your opinion, is the best treatment approach for a child diagnosed with DS?
Various therapies like Physical therapy, Audio therapy, Speech-language therapy, Occupational therapy, Assistive technology, Special education are available in most cities today. The main approach is to keep in mind what to look out for, and to address those symptoms accordingly.
Can you suggest some support groups (online or offline), NGOs or government agencies in your city/India that offer support to individuals with DS?
There are several support groups available for children with Down syndrome. The ‘Down Syndrome Federation of India’ is one such organization sharing information, counseling and therapies for people affected with Down syndrome. Several support groups are also available. Besides, there are Facebook groups to help people with information and support. Down Syndrome International having worldwide events has an Asia Pacific Chapter. At a local level, there are Whatsapp groups offering support. Many cities have dedicated schools run by missionaries/by NGOs, e.g., Dilkhush in Juhu, Mumbai.
Can DS be cured? Does stem cell or gene therapy have any role here? If yes, where can it be done and what is the cost involved?
Once a baby is born with Down syndrome, the condition cannot be reversed. Therefore, prevention becomes of prime importance. The only approach for any affected baby would be the treatment of the symptoms as they manifest themselves.
A couple of centers have experimented with the use of human embryonic stem cells for the treatment of Down syndrome and reported near normal outcome. Some others have tried ‘silencing’ the extra chromosome to control clinical manifestations. There are no confirmed and proven methods of treating Down syndrome by using stem cells or gene therapy.
Are you aware of any DS clinical research trials currently going on in our country?
There are several trials going on both in the private as well as government sector on various aspects of the condition—developmental, risk of heart disease, renal complications, Down syndrome with leukemia (ALL), etc. Faculty of Clinical Research (IGMPI) would have the information.
What is the one advice that you would like to give to the parents having children with DS?
Be patient. Your child is differently abled. He may require some special attention, and a lot of love and understanding. It is not the fault of any of the partners that has resulted in this condition in the child. This is an error in nature (error during fertilization). So accept it, and move on.
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