The further development of enzyme assays demonstrated that levels of hexosaminidases A and B could be measured in patients and carriers, allowing the reliable detection of heterozygotes. During the early 1970s, researchers developed protocols for newborn testing, carrier screening, and pre-natal diagnosis. By the end of 1979, researchers had identified three variant forms of GM2 gangliosidosis, including Sandhoff disease and the AB variant of GM2-gangliosidosis, accounting for false negatives in carrier testing. Society and culture
Since carrier testing for Tay–Sachs began in 1971, millions of Ashkenazi Jews have been screened as carriers. Jewish communities embraced the cause of genetic screening from the 1970s on. The success with Tay–Sachs disease has led Israel to become the first country that offers free genetic screening and counseling for all couples and opened discussions about the proper scope of genetic testing for other disorders in Israel.Because Tay–Sachs disease was one of the first autosomal recessive genetic disorders for which there was an enzyme assay test (prior to polymerase chain reaction testing methods), it was intensely studied as a model for all such diseases, and researchers sought evidence of a selective process. A continuing controversy is whether heterozygotes (carriers) have or had a selective advantage. The presence of four different lysosomal storage disorders in the Ashkenazi Jewish population suggests a past selective advantage for heterozygous carriers of these conditions. "This controversy among researchers has reflected three debates among geneticists at large:
Dominance versus overdominance.
Other significant issues involve the difficulty in crossing the blood–brain barrier, as well as the great expense, as each unit of cord blood costs $25,000, and adult recipients need many units. Gene therapy
On 10 February 2022, the first ever gene therapy was announced, it uses an adeno-associated virus (AAV) to deliver the correct instruction for the HEXA gene on brain cells which causes the disease. Only two children were part of a compassionate trial presenting improvements over the natural course of the disease and no vector-related adverse events. References
External links

GeneReviews/NCBI/NIH/UW entry on hexosaminidase A deficiency, Tay–Sachs disease
NINDS Tay–Sachs Disease Information Page
Tay–Sachs disease at NLM Genetics Home Reference
Tay–Sachs on NCBI