Tay–Sachs disease is a recessively inherited disease of brain lipid metabolism. The most common form of Tay-Sachs disease becomes apparent in infancy.
Check out our 31 interesting facts about Tay-Sachs disease:
1) It is caused by a mutation in the gene (genes are located on chromosomes and serve to direct specific processes and developments within the physical body) responsible for the essential enzymes called beta hexaminidase A (Hex-A).
2) Without hexaminidase A, a fatty substance (called GM2 ganglioside) accumulates abnormally in cells, particularly in the nerve cells of the brain. This ongoing accumulation causes progressive damage to the cells.
3) The less beta-hexosaminidase A a person has, the more severe the disease and the earlier the symptoms appear.
4) A child can only get TSD by inheriting the gene for it from both parents.
5) When two-carrier parents have children, three outcomes are possible:
- both parents pass the gene mutation to the child. The child will suffer from the disease, depending upon the mutations passed, but, he will likely die at a very young age;
- one parent passes the gene mutation to the child but the other does not. Then, the child will not suffer from the disease, however, it will be a carrier of the TS gene;
- both parents do not pass the gene mutation to the child. The child will be healthy and live a normal life.
6) TSD generally strikes in early life (3-6 months of age), however, it can also not appear until youth or strike in adulthood.
7) The main symptoms of the disease include:
- seizures (fits);
- being overly startled by movement and noises;
- muscle stiffness;
- loss of hearing or vision;
- difficulty swallowing;
- weakness, that keeps getting worse until the sufferer is unable to move;
- losing the skills which he or she has already learned;
- being very slow to reach milestones, such as – learning to crawl.
8) There are 3 forms of TSD, distinguished by the general age of onset:
9) Classic Infantile Tay-Sachs – the symptoms appear around 6 months of age. The infantile form of TSD is characterized by an almost complete lack of Hex-A enzyme activity.
10) Juvenile Tay-Sachs – the symptoms usually occur between ages 2 and 5, however, they can occur anytime during childhood. Generally, one of the first symptoms is problems with coordination.
11) Late Onset Tay-Sachs – the symptoms generally occur in adolescence or early adulthood. Initial symptoms associated with late-onset TSD include:
- progressive muscle weakness;
- mood alterations;
12) The disease is named after Bernard Sachs (in 1887, he described the cellular changes and observed a significantly increased rate of disease in Ashkenazi Jews) and Waren Tay (in 1881, he described a red spot on the retina of the eye).
13) By the mid-1960s, TSD was recognized as one of a few conditions, including Gaucher and Niemann-Pick diseases, where the absence of a normal degradative enzyme allows the accumulation of cellular waste components. These, over time, destroy normal organ function.
14) A rare breed of sheep has been used as a model in the research of TSD, due to their susceptibility to the disease.
15) The TS blood test, also known as the carrier screening, identifies TS non-carriers and carriers.
16) Besides enzyme assays of Hex-A activity, the diagnosis can also be done via genetic testing using polymerase chain reaction. This method of diagnostic is particularly used when the ancestry of both parents is known.
17) Prenatal testing for TSD can be performed around the eleventh week of pregnancy using chorionic villi sampling. Between the 15th and 18th weeks of pregnancy, a woman can have an amniocentesis to test for the TS gene.
18) There is no cure for any form of TSD.
19) A few different therapies are being explored as potential treatments for TSD. They include:
- pharmacological chaperone therapy;
- substrate inhibition;
- enzyme replacement therapy;
- stem cell therapy;
- gene therapy.
20) Enzyme replacement therapy has been considered a treatment method for TSD and other lysosomal storage disorders.
21) A treatment aimed at inhibiting gangliosides synthesis is presently being investigated for the slowly progressive forms.
22) In the early 2000s, a team of researchers in Germany and Italy demonstrated that they could reduce the symptoms of the TSD in afflicted mice by injecting them with a virus which infected their cells with a gene they lacked.
23) Children born with juvenile TS typically die before the age of 15.
24) Children born with infantile TS, even with the best available treatment, generally die before the age of 5.
25) The late-onset type doesn’t always shorten life expectancy.
Ashkenazi Jewish and The ”Jewish Disease” Inheritance
26) TSD is frequent in the Ashkenazi Jewish population and French Canadians. According to statistics, in these populations, 1 in every 27 people carried a TS gene mutation.
27) Also, in the Ashkenazi Jewish population, the TSD incidence is about 1 in every 3,500 newborns.
28) The most convincing theory as to why the TSD disproportionately affect the Ashkenazis Jewish population is that they mostly married within their own community, leading to the mutation to become more frequent.
29) Carrier screening programs for TSD have reduced the disease incidence by 90 percent. Worldwide, since 1970, over 1.4 million people have been screened voluntarily to determine if they are carriers of the mutant gene for TSD.
30) The next highest risk population is people of Irish-American descent. According to the data, people of Irish ancestry have a 1 in 50 chance of being a carrier of the TS gene.
31) Around 1 in every 300 people who are not of these backgrounds is a carrier for the TS gene.