[5] Following this, some of the genetic mechanisms underlying Lynch syndrome were elucidated during the 1990s and the significance of tumours outside the colon, such as those of the endometrium, small intestine and ureter, became clearer.
These changes in the knowledge of the syndrome lead to a revision of the Amsterdam criteria and were published in Gastroenterology journal in 1999.
They were formulated to serve as a common starting point for future research into the genetics underlying the disease.
These were called the Amsterdam II clinical criteria for families with Lynch syndrome.
[4][6] Each of the following criteria must be fulfilled: In 1997, the National Cancer Institute published a set of recommendations called the Bethesda guidelines for the identification of individuals who should receive genetic testing for Lynch syndrome related tumors.