Red spot on the Retina?? Could be fatal TSD!!

Tay-Sachs disease (TSD), a rare genetic disorder is also called as Hexosaminidase A deficiency and is innate in an autosomal recessive pattern (where both copies of the gene in each one cell have mutations). The disease is named after an ophthalmologist ‘Warren Tay’ (British by origin) that firstly described and identified the red coloured spot on the retina of the eye in year 1881 and there after an American neurologist B. Sachs primarily explained the cellular changes involved in TSD. This disease is caused when unfavourable quantities of ganglioside, a fatty acid derivative mount up in the nerve cells of our brain. Further researches in late 20th and early 21st centuries verified that TSD is caused due to the mutations on the HEXA gene on chromosome number 15. This HEXA gene supply instructions for the formation of a part of beta-hexosaminidase A enzyme, located in lysosomes and have a crucial role in the spinal cord and brain. A large number of HEXA mutations have been discovered and advanced researches are still going on and a fact which came into light is that most of the HEXA mutations are extremely rare and do not occur in genetically isolated populations. Most of the cases are found in people of central and eastern European countries especially in Cajun and Amish community in Louisiana and Pennsylvania.
TSD can occur at any age and stage but the most common one is in infancy. Both the parents carry one copy of mutated gene each, but may or may not show symptoms of this condition. These mutations in the HEXA gene upset the functioning of beta- hexosaminidase A, which avert this enzyme from breaking down GM2 ganglioside resulting into its accumulation up to a toxic level in brain and further causing problems.
Broadly TSD can be divided into three levels depending upon the age at which it occurs:

Infantile TSD
Disease becomes noticeable after first six months of life resulting into muscle atrophy and paralysis. Death occurs before the age of 4-5 years

Juvenile TSD
Very rare case when disease appears in the age group of 2-10 years followed by speech, motor and swelling difficulties. Death occurs between 5-15 years of age.

Adult TSD
Rare form of TSD occurs in the age group of 20- 30’s followed by neurological weakening, unsteadiness of gait, psychiatric illness like schizophrenia resulting into restricted movements and physical complications.

A child can have Tay-Sachs disease only & only if both the parents are carrier of the genes. When two carriers have a child together i.e (MCarrier x FCarrier)
50% possibility that their infant will be a carrier(ICarrier), but not have the disease
25% possibility that their infant (IDisease ) will have the disease
25% possibility that their infant (I Healthy ) will not be a carrier and not have the disease too.

Location of HEXA gene: positioned on the long (q) arm of chromosome 15 between 23 & 24 positions.

U.S. National Library of Medicine®

There is at present no cure for TSD. After an extensive medical care too, children with infantile TSD suffers and die by the time they reach the age of 5 or 6 and the sufferings in Adult TSD can only be slowed down with the help of drugs and treatments. Various methods of treatment like Substrate reduction therapy, Gene therapy, Enzyme replacement therapy (Gregory M. Pastores, 2006) is still under experimental stages. Anticonvulsant medicine might primarily manage seizures. Other compassionate cure includes apposite nutrition and hydration and techniques to carry on the airway open. Children may ultimately need a feeding hose or pipe.



Click here for more details and for comprehensive reading about the Tay-Sachs disease