Which disease is associated with joints in humans?

Deposition of . . . . . . in the joints causes gout.

Gout happens due to the accumulation of $...$ in joints.

'Paraplegia' refers to the paralysis of

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$:
Osteoporosis is characterised by decreased bone mass and increased chances of fractures.
Reason $(R)$:
Common cause of osteoporosis is increased levels of estrogen.
In the light of the above statements,choose the most appropriate answer from the options given below:

Chronic autoimmune disorder affecting the neuromuscular junction, leading to fatigue, weakening, and paralysis of skeletal muscle, is called: