Taking the gene test
The 46 chromosomes or genetic material that we inherit from our parents are responsible for more than just shaping our physical characteristics. They can give us insight into the kind of diseases we could be exposed to
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In 2012, Madurai-based Avinash Shetty, then 30, was busy making arrangements for his wedding. But festivities were not the only thing on his family’s mind. With serious health scares on both sides, his fiancée and he were aware they had the odds stacked against them in the genetic department. “My mother-in-law had succumbed to leukaemia and my mother was suffering from lung carcinoma and diabetes. Plus, I was (and still am) a smoker,” says Shetty. “My mother, a nurse, insisted that my future bride and I get genetic testing done,” he says. Blood and tissue samples were sent for testing. “Fortunately, there was nothing amiss.” The couple married and now have two daughters.
The 46 chromosomes or genetic material that we inherit from our parents are responsible for more than just shaping our physical characteristics. They can give us insight into the kind of diseases we could be exposed to. “With a single blood test, doctors are now able to analyse our risk to disease at the DNA level and tell in advance the kind of illness you might possibly develop,” says Mumbai-based Priyanka Raina, genetic counsellor at Positive Bioscience, a clinical genomics company, and consultant at Saifee Hospital.
The study of a person’s DNA to identify various mutations is called genetic testing. Genomic medicine is the broad discipline—basically medical care attuned to the body’s unique genetic make-up. So, when you get tested for disease based on your genetic coding, it is called genetic testing. The medical care that results is genomic medicine.
“Advances in genomic medicine are the results of ground-breaking research. We expect it to transform the very fabric of healthcare,” says Samarth Jain, founder and chief executive officer of Positive Bioscience, which offers genetic testing and evaluation of one’s risk for disease.
Perhaps the most famous example of genetic diagnosis is Angelina Jolie’s preventive breast surgeries in 2013. A simple blood test showed the actor carried the BRCA1 gene, which meant she had an 87% risk of contracting breast cancer and a 50% risk of ovarian cancer. She knew she had a strong family risk for both diseases, since her mother and aunts had succumbed to them. Jolie removed her breasts, uterus and fallopian tubes in successive operations.
Shortly afterwards, there were reports of a steady rise in demand for pre-emptive surgeries by women. Doctors still advise caution, however; they say pre-emptive surgery necessitates a thorough assessment of risk factors, age and family history.
“While pre-emptive surgery isn’t the norm in India yet, there is a growing awareness about genetic diagnosis, especially in the area of cancer prediction and treatment,” says Vikas Goswami, senior oncologist at the Fortis Hospital in Noida, near Delhi. “But in many cases, even as we’re able to assess our risk to cancer, we won’t always have the medicine to treat it. And that is a very real vulnerability.”
To be able to diagnose whether we may be at risk of the disease is only part of the story. “We need to be able to answer questions such as what the nature of this disease would be, what drugs would be effective, can we predict whether the cancer would spread or recur. We hope that genetic research can provide answers to these in the days ahead,” says Dr Goswami.
“In addition to cancer, genomic testing has opened up our world to many other diseases that could possibly be diagnosed or predicted, such as cardiovascular diseases, diabetes, autism spectrum diseases and neurological disorders,” says Radhika Vaishnav, a Vadodara-based genetic scientist and executive editor of the International Journal Of Molecular ImmunoOncology. “Being able to treat previously ‘untreatable’ conditions is becoming a reality today,” she adds. “However, though far more accessible (with costs half of what they were in 2011), genetic testing is still in its infancy in India. This is because genomic medicine relies on Big Data (comparing the genetic data of millions of people) for its accuracy in the prediction of disease. There are concerns that there is not enough Indian population-specific data to compare and accurately predict disease risk.”
Since the 1970s, blood tests have been conducted routinely during pregnancy in India to rule out genetic diseases such as Down’s Syndrome. “Today, we’re able to catch rare genetic disorders earlier,” says Seema Thakur, senior consultant, genetics and foetal diagnosis, at the Indraprastha Apollo Hospitals in New Delhi. “Diseases like thalassemia (an inherited blood disorder requiring frequent blood transfusion), dwarfism and Gaucher’s (an inherited disorder in which the body’s ability to store fats is compromised, accumulating it in the body’s tissues, cells and organs) are now being identified early.”
Great strides have also been made in the treatment of muscular dystrophy (MD), a genetic disorder which causes progressive muscular degeneration and weakness. Of the nine kinds of muscular dystrophy, Duchenne Muscular Dystrophy (DMD)— the most common one—is manageable after prenatal genetic testing. “DMD can begin as early as the age of 3. By the time a child reaches his/her teens, their muscles progressively waste away and they will find themselves in a wheelchair. By the age of 21, the disease can prove fatal,” says Berty Ashley, senior research associate at the Dystrophy Annihilation Research Trust, a non-profit in Bengaluru. “DMD occurs because a certain gene in our bodies (incidentally the largest gene we have) called the dystrophin gene is not copied in its entirety when it is passed on to the child in the womb. The gene is made of 79 exons, structures that fit like a jigsaw puzzle. When the gene is transferred to the child, any exon, for example, is missing or deleted,” says Ashley.
In September, the US food and drug administration approved the use of new medication (dystrophy eteplirsen) for this. “Taking this drug during pregnancy will introduce the missing genetic strand in the child. It won’t cure the disease but it could effectively hamper its progression,” says Ashley. A child will still have weak limbs, but he will be spared a life in a wheelchair or premature death.
Dr Thakur, however, believes that genetic testing without sustained counselling both before and afterwards could lead to greater stress for patients.
“Genetic testing is extremely expensive (ranging from Rs12,000 to Rs1.5 lakh) and not all (diagnostic) labs offer standardized results. If you are faced with an incurable disease, there is little you can do. It could cause great anxiety,” she says.
It is disturbing that people are requesting tests on their own because emotionally, they may not be equipped to handle the results. “Adequate counselling and follow-up on treatment/medication are important,” Dr Thakur explains, adding, “There is no doubt that our knowledge of genetic diagnosis will bring with it greater responsibility.”
Where to go
Places that provide prenatal diagnostic services and genetic diagnosis
■The Indian Council of Medical Research in Mumbai provides prenatal diagnostic services (www.icmr.nic.in)
■The genetics unit, department of paediatrics, All India Institute of Medical Sciences, New Delhi (a World Health Organization collaborating centre) offers genetic diagnosis, prenatal diagnosis and counselling (www.aiims.edu)
■ Genetic blood tests and counselling are offered at hospitals across the country such as Apollo (Madurai, Chennai), Saifee (Mumbai), Kokilaben Dhirubhai Ambani Hospital, Breach Candy (Mumbai) and Medanta—The Medicity (Gurugram).