X-linked dystrophies

Question 1

What is the inheritance pattern of both DMD and BMD?

Answer 1

X-linked recessive

Question 2

What are the two kind of X-linked muscular dystrophy?

Answer 2

Becker’s and Duschenne

Question 3

What is the difference in onset between BMD and DMD?

Answer 3

DMD has an earlier onset and is more severe

-BMD onsets later and some affected don’t lose the ability to walk

Question 4

What is normal life span for DMD patients?

Answer 4

-late teens to early twoenties

Question 5

What is the lcoation and name of the protein resoinsible for both DMD and BMD?

Answer 5

• Short arm of the X-chromosome
• Dystrophin is the protein that is lacking

Question 6

How much dystrophin is present in DMD and BMD patients?

Answer 6

• DMD: none or very little
• BMD: reduced amounts, size, and function

Question 7

What kind of mutation is responsible for DMD?

Answer 7

-Frameshift mutations caused by deletions or duplication of an exon

Question 8

-What kind of mutation is responsible for BMD?

Answer 8

-Typically non-frameshift mutations.

Question 9

What is the role of dystrophin?

Answer 9

• part of the complex joining the intracellular cytoskeleton to the extracellular matrix.
• interacs with structural actin and B-dystroglycan

Question 10

What plasma protein is elevated in DMD and BMD? How much in each?

Answer 10

• Creatine kinase.
• Severly elevatin in DMD but only midly in BMD
• also slightly elevated in DMD carriers

Question 11

What is the basis of diagnosis for DMD and BMD?

Answer 11

• H&P and measurement of Serum CK.
• Confirmed by muscle biopsy or DNA analysis

Question 12

What are the two kinds of DNA analysis used to diagnose DMD and BMD in newborns as well as carriers and fetal?

Answer 12

• Multiplex PCR
• Single Condition amplification/internal primer sequencing (SCAIP)