Spinal Muscular Atrophy

Question 1

What is SMA?

Answer 1

A condition in which the ventral (anterior) horn of the spinal cord is affected

Alpha motor neuron dies

Question 2

What kind of symptoms would you see?

Answer 2

LMN symptoms

Question 3

There is 4 types:
Type I -> Type IV

What is the worst?

Answer 3

Type Ia - starts before birth

Type Ib - babies tend to only survive a few years as eventually go into resp failure

Question 4

What is the kind of inheritance?

Answer 4

Autosomal recessive

Question 5

It comes around due to a deletion of SMN1 gene which produces SMN proteins which help to maintain the alpha motor neuron.

If this is deleted then why do not all alpha motor neurons die?

Answer 5

You also have SMN2 gene which is 99% the same apart from one base

This also codes for SMN proteins but most are non-functional

The more copies of SMN2 gene you have the less severe your form of SMA

Question 6

How is it managed?

Answer 6

Supportive treatment from birth