Last week I went to a retirement party for Dr. Sachiko (Sachi) Nakagawa, a former colleague of mine from my time in the genetic testing lab at Jacobi Medical Center. When preparing for the speech I delivered at the party, I reviewed her invaluable contributions in the realm of Tay-Sachs disease screening, and I thought that you all needed to hear a bit (or maybe more than just a bit) about those.
Sachi was trained as a biochemist and ended up here at Einstein in the late 1960s for additional training after receiving her Ph.D. In the early 1970s, she joined the group of Dr. Harold Nitowsky, who was on the verge of setting up the Tay-Sachs community carrier screening program known as Operation Gene Screen. To quote Sachi directly, “this is how I ended up doing Tay-Sachs carrier screening till now … and nobody told us we made any mistake for the last 40 years.”
Forty years devoted to Tay-Sachs enzyme screening! Hard to imagine—especially if you knew that she hardly missed a day of work or took a vacation! Sachi must have tested tens of thousands of samples, starting with for the early Einstein screens, and then for commercial laboratories, for infertility clinics, and for Jewish genetic screening programs nationwide, including our own Program for Jewish Genetic Health. To Sachi, the focus was never the total number of samples—each sample was treated with the utmost care, and each was tested and retested to ensure an accurate classification.
One of Sachi’s most important technical contributions was her development of the platelet assay for Tay-Sachs carrier testing. Until Sachi’s platelet test, Tay-Sachs testing of Hex A enzyme activity was being performed on serum (the part of your blood that is neither a blood cell nor a clotting factor). While this was a good test for identifying carriers, many samples were yielding inconclusive results. I remember Sachi describing to me her “aha moment.” While at a scientific conference, she realized that platelets (a component of the blood that is important for clotting) would be a much more homogenous sample than serum, and could possibly overcome the significant number of inconclusives. And Sachi was correct about this. Her platelet assay became the gold standard test that not only was a gift to the Jewish screening programs but also helped to identify Tay-Sachs carriers from ethnic backgrounds that were not 100% Ashkenazi Jewish.
Along that line, it is important to recognize that Tay-Sachs disease, in addition to in the Ashkenazi Jewish population, also is seen more frequently in other populations including the Irish, French Canadian, and Cajun—and this is something that is often overlooked (but see also an earlier blog). I will never, ever forget an email exchange I had with Sachi when she was asked to confirm a probable diagnosis of Tay-Sachs in a sample from a baby of Irish descent. “There is no HexA enzyme peak,” she related, “the baby is affected with the disease.” Thankfully, we don’t see much of this anymore in the Jewish population due to the carrier screening programs, and hopefully the same trend will follow in other prone populations in the future.
A co-worker of Sachi’s told me that, on Sachi’s last day in the laboratory she said goodbye to her instrumentation and thanked it for its stellar performance. And hearing that made me give pause for thought. The world of genetic testing is moving at rapid fire pace these days. It is important to remember that, before DNA was discovered, and before the genes and mutations associated with specific diseases were characterized, there were biochemical genetic tests, some of which are still being used today (today we test for Tay-Sachs carriers both by looking for mutations on the DNA level and by assessing enzyme levels). People like Sachi, who developed and ran these tests in the most dedicated manner, will never be forgotten by her colleagues. I hope that she also will be remembered by the countless screened individuals who benefited from her expertise, as well as by the community as a whole. Kudos to you, Dr. Sachiko Nakagawa.