Genetics of CNS Disease

Question 1

Which type of inheritance is displayed in Duchenne’s muscular dystrophy?

Answer 1

X-linked recessive

Affects males only.

Question 2

What are features of Duchenne’s muscular dystrophy?

Answer 2

Shoulder girdle weakness at 3-4yo. Progressively worsens, with wheelchair in teens and eventual death in 20s.
Gower’s sign
Calf hypertrophy
Muscle weakness

Question 3

What is Gower’s sign?

Answer 3

When patient uses their arms to compensate for pelvic weakness when trying to stand up.

Question 4

How is Duchenne’s muscular dystrophy diagnosed?

Answer 4

Measure serum CK and perform EMG initially
Biopsy
Genetic testing (best method)

Question 5

Why do X-linked recessive conditions only affect males?

Answer 5

As they only have one X chromosome.

Question 6

What gene is affected in Duchenne’s muscular dystrophy?

Answer 6

Dystrophin gene.

Question 7

What pattern of inheritance is seen in Huntington’s disease?

Answer 7

Autosomal dominant

Question 8

What pattern of inheritance is seen in spinal muscular atrophy?

Answer 8

Autosomal recessive

2 faulty copies needed.

Question 9

What gene is involved in spinal muscular atrophy?

Answer 9

SMN1 gene.

Question 10

What are features of spinal muscular atrophy?

Answer 10

Hypotonia
Muscle weakness
Muscle wasting