Genetics Of Msk Disorder

Front 1

What is the normal function of dystrophin? Name 2 disorders from abnormality of dystrophin.

Back 1

Dystrophin - maintain the integrity of skeletal and cardiac muscle cystoskeleton.
Disorders: Becker's and Duchenne muscular dystrophy

Front 2

Becker and Duchenne muscular dystrophy are example of pleiotrophy. What is the definition of pleiotrophy (or genetic heterogeneity)?

Back 2

Pleiotrophy - a single mutation affects several apparently unrelated aspect of the phenotype. "One gene two diseases".

Front 3

Polygenic is the opposite of pleiotrophy. What is the definition of polygenic?

Back 3

Polygenic - disorders which is determined by a number of different genes. "Many genes same disease".

Front 4

There are 2 main types of muscular dystrophy. What are they and how are they different?

Back 4

Becker (BMD) and Duchenne Muscular Dystrophy (DMD). Both are due to defective or absent dystrophin protein and characterised with muscle weakness. BMD is benign form of DMD which produces partially functional dystrophin. BMD has a later presentation (early teen) than DMD. DMD has absent of dystrophin and have early presentation (children).

Front 5

What is the inheritance pattern of muscular dystrophy?

Back 5

X-linked recessive. Fathers cannot pass to son. Female carriers may develop some muscle weakness.

Front 6

What are the determinants of osteoporotic risk?

Back 6

Age (LAO)
Gender (50% women, 25% men)
Race
Vitamin D intake
Family history
Oestrogen status

Front 7

What have protective effects against osteoporosis?

Back 7

Oestrogen
Exercise
High BMI

Front 8

Osteoporosis Pseudoglioma (OP) is a single gene disorder that might give some hints about osteoporosis. What gene is associated with it?

Back 8

It is an autosomal recessive due to the mutations in the LRP5 (Low Density Lipoprotein receptor related) gene. It is expressed in osteoblast.