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How reliable is TW3 test for age verification?

How reliable is TW3 test for age verification?


Published: 7 Aug 2020 12:05 PM GMT

The national tennis federation AITA has announced introduction of TW3 test to tackle the menace of age fraud in the sport but experts have spelled out the limitations of the popular method and suggested adoption of more reliable techniques like the FELS method and "epigenetic clock".

The experts are divided on using the Tanner Whitehouse 3 (TW3) method but it is largely believed, even by the International Olympic Committee (IOC), that it is inconclusive. However, since it is widely used and considered one of the accurate methods, leading sports federations in the country including the BCCI, the All India Football Federation (AIFF) and the Sports Authority of India (SAI) subject the players to TW3 test.



Assessment of skeletal maturity are made from handwrist radiographs, using either the method of Greulich-Pyle (GP), Tanner-Whitehouse (TW) or FELS method. The Blood samples, Ultrasound, and MRI are non-radiation methods but they too are not sufficient according to IOC. The TW3 method uses X-Rays of the left hand and wrist to examine the skeletal maturity of a person to determine their bone age.

In wrist scans, age is estimated by looking at 20 or so bones initially separated by cartilage, but which progressively move closer to one another until they fuse in the mature wrist. One of the reasons for using left hand and wrist radiographs is that most people are right-handed, and therefore, the right hand is more likely to be injured than the left hand.



Dr Sunita Kalyanpur and her Radiologist husband Arjun Kalyanpur, who conducted the TW3 tests on about 3000 footballers for the AIFF, admit that it's not 100 percent accurate but asserted that it's very close to determining the actual age.

"The technology has changed drastically in the last few years. We use a Danish software. The process is much more refined. It takes less than a minute and there is no risk to the child. Earlier the gap with the actual age was up to four years but it's hardly 6 to 9 months now. TW3 is the most accurate method," Arjun said. However, experts say that chronological age could be different from the biological age by as much as 2-3 years, whichever method is used.

"The child who is an early developer could look biologically 16 years old even though he or she may be just 13 or 14 years old. Research has shown that in team sports, children who are bigger and stronger are more likely to be chosen and on testing are invariably biologically more mature. This means that the late developers are less likely to be chosen as they are usually smaller and weaker even though all differences will be equalised when they are fully mature," said Amanda Johnson, who worked as a physio with the Manchester United Football Club (MUFC).

Amanda also explained that MUFC had conducted a study to investigate the differences between skeletal and chronological age. "The study found that around 30% of players are either late or early developers, suggesting that many players undergoing training in age-defined groups might not benefit optimally from prescribed training regimens." Amanda recommends that more competitions should be introduced in the junior ranks which consider Bio-banding where players compete against each other as per their body weight and potential size.

"This method has been successfully introduced by the Premier League in several junior tournaments. The taller and stronger players compete against their matching rivals and it's a battle between equals." She also strongly recommended that if skeletal X-rays are to be used for age determination, they should be assessed using the FELS technique. In this method, skeletal maturity indicators are measured (58 binary indicators, 27 ordinal indicators and 13 continuous measures).



The IOC in its consensus statement (June, 2010) on age determination in high-level young athletes had said, "The onset and rate of growth and maturation varies widely between individuals during adolescence, and consequently the maturational status of children of the same age also differs.... the assessment of skeletal age by X-ray scanning is limited and does not allow a precise determination of the chronological age. Variations up to several years in bone age have been observed in adolescents of the same chronological age."



Sports Medicine expert Dr Saranjeet Singh, based in Lucknow, said 'epigenetic clock' is a better method for determining the age of an individual. "In the epigenetic clock method we look at molecular markers called methyl groups that can get added or removed from DNA. The study of these and similar DNA markers is called epigenetics and is currently a very new and active field of study," Singh said.

"It turns out that some of these methylation sites can steadily accumulate or decrease in specific ways as a person ages. This can be used as an 'epigenetic clock'. In a recent breakthrough, biomarkers of ageing based on DNA methylation data have enabled accurate age estimates for any tissue across the entire life course.

These ‘epigenetic clocks’ link developmental and maintenance processes to biological ageing, giving rise to a unified theory of life course." However, the DNA methylation test cost varies, from Rs 14,000 to 18000, which is much more than the TW3 which would cost not more than Rs 2000.

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