Question

Tay-Sacs Disease is..?

a
a fatal disorder
b
a lipid disorder
c
a neurological disorder
d
a and c
e
all of the above
f
none of the above

Answer 1

e...

Explanation:

Tay-Sachs, like the closely related Sandhoff disease, is a genetic disorder: a defective gene for an enzyme called `beta`-hexosaminidase. This enzyme is involved in the breakup and clearance of a class of lipids called gangliosides.

These are so named, because they were first isolated from ganglion cells in the brain.

Gangliosides are continuously synthesised and broken up. The breakdown occurs in Lysosomes . If `beta` -hexosaminidase is inactive, then the gangliosides are not broken down. As a result the lysosomes swell up and eventually hinder the neurons in their normal function, invariably resulting in a general deterioration in mental and physical capabilities, most notably blindness, deafness and paralysis .

Tay-Sachs usually manifests itself within the first year. Known as Infantile TS, this form usually leads to death within 4-5 years.

A more rare, and less severe form is Juvenile TS. The first symptoms usually occur between the ages of 2 and 10. Life expectancy is 5-15 years.

Thirdly, another rare form is Adult-Onset TS. The signs of this variant usually start appearing in a patient's 30's or 40's. Unlike the first two, it is not always lethal, though sufferers usually end up in a wheelchair towards the end of their life.

Back to the question:

• a : Is it fatal? `rarr` Yes: Usually, though not always...
• b : Lipid disorder? `rarr` Yes , it is classified as an inborn error of lipid metabolism.
• c : Neurological disorder? `rarr` Yes . Not directly though, as the neurological abberations are a result of the metabolism
  error.

From this, it follows that the correct answer should be e.....