about the genetic principle governing the disease , the symptoms and treatment associated with it

1. PREPARED BY
MONISHA MITRA
SHAYREE CHATTERJEE
MSc (Ag) 2nd year
THIRD SEMESTER
DEPARTMENT OF GENETICS
AND PLANT BREEDING
SUBJECT : CELL BIOLOGY
AND MOLECULAR
GENETICS (GPB 601)

2. Warren Tay
Bernard
Sachs

3. What is Tay-Sachs?
• A fatal genetic disorder
• Most commonly occurring in
children
• Results in progressive
destruction of the nervous
system
• Caused by the absence of a
vital enzyme called
hexosaminidase-
A (Hex-A).
• Tay-Sachs disease results
from defects in a gene on
chromosome 15 that codes
for production of the enzyme
Hex-A.

4. • Mutations in the HEXA gene disrupt the activity of
beta-hexosaminidase A (prevents the enzyme from
breaking down GM2 ganglioside).
• The HEXA gene provides instructions for making
part of an enzyme called beta-hexosaminidase A,
which plays a critical role in the brain and spinal
cord.
• This enzyme is located in lysosomes, which are
structures in cells that break down toxic substances
and act as recycling centers.
• Within lysosomes, beta-hexosaminidase A helps
break down a fatty substance called GM2
ganglioside.

5. • As a result, this substance accumulates to toxic
levels, particularly in neurons in the brain and spinal
cord.
• Progressive damage caused by the build up of
GM2 ganglioside leads to the destruction of these
neurons, which causes the signs and symptoms of
Tay-Sachs disease.
• Because Tay-Sachs disease impairs the function of
a lysosomal enzyme and involves the buildup of
GM2 ganglioside, this condition is sometimes
referred to as a lysosomal storage disorder or a
GM2- gangliosidosis.

8. Without
Hex-A
A fatty
substance
GM2
gangloside
Accumulate
abnormally
in the cell
Especially in
nerve cells
of the brain
Cell damage
and death

9. How do people inherit Tay-Sachs
disease?
• Tay-Sachs disease is inherited in an autosomal recessive
manner.
• This is one way a disorder or trait can be passed down
through a family.
• Everyone has two copies of the HEXA gene; one received
from their father and one from their mother.
• Autosomal recessive inheritance means that a person
receives a nonworking copy of the HEXA gene from both
parents.
• The parents have one working copy of the gene and one
nonworking copy; they are carriers for Tay-Sachs disease.
Carriers do not develop symptoms of the disorder.
• If two people who are carriers have Tay-Sachs disease,
there is a 25% chance with each pregnancy that the child
will have the disorder and a 50% chance the child will also
be a carrier

11. Basic symptoms of this disease