History of Tay-Sachs Disease Genetic Research
Up until the latter half of the twentieth century, Tay-Sachs disease was thought to be a disease of infants only, and later-onset forms of the disease were not recognized as being Tay-Sachs. In the 1970s and 1980s, as new information about the molecular biology of the disease was uncovered, it was determined that adult-onset forms of the disease did exist.
Tay-Sachs is now known to be an autosomal recessive genetic disorder, which means that a child born with the disease has inherited a defective copy of the HEXA gene from each parent.
Much genetic information about the disease has been uncovered in the twenty-first century. By the year 2000, more than one hundred different types of mutation in the HEXA gene had been discovered as a result of genetic testing of people known to be carriers of a mutated gene. All of the HEXA mutations so far discovered have resulted in Hex-A enzymes that are either non-functional, or function abnormally.
Bernard Sachs originally noted the prevalence of Tay-Sachs in Ashkenazi Jews more than one hundred years ago, but more recently it has been discovered that certain other cultural or geographic populations also have a higher incidence of HEXA gene mutations.
These include the Cajun population of southern Louisiana, where it has been noted that among this group of people exists the very same HEXA gene mutation that is so prevalent in Ashkenazi Jews. Genealogical research indicates that this mutation can be traced to a single French couple who lived in the eighteenth century.