A molecular marker is a DNA sequence fragment indicating specific biological processes, particularly in relation to muscular dystrophy, a group of inherited diseases causing muscle degeneration. The mutations in the dystrophin gene on the X chromosome lead to Duchenne and Becker muscular dystrophy, with various types of mutations including deletions and point mutations identified through different genetic analysis methods. Dystrophin's protein complex connects muscle fibers to the extracellular matrix, and disruptions in this complex result in muscular dystrophy.

2. A molecular marker (genetic marker) is a
fragment of dna sequence that associated to
a part of the genome.
It is used as an indicator of a specific
biological process occurring in the body.

3. The term muscular
dystrophy refers to a
group of inherited
muscle-destroying
diseases that cause
progressive degeneration
of skeletal muscles.

4.  Duchenne muscular dystrophy (DMD)
 Becker muscular dystrophy (BMD)

5. Markers in muscular dystrophy
DMD(Dystrophin) gene
was discovered by Louis
M. Kunkel in 1986 , that
the dystrophin mutated
gene causes muscular
dystrophy.

6.  Dystrophin is a gene located in the X
chromosome.
 It codes for the dystrophin protein.
 Mutations in the dystrophin causes Duchenne
and Becker muscular dystrophy.

7. Position 21.2
GENE LOCUS

8. STRUCTURE OF DYSTROPHIN:
Dystrophin is a rod shaped cytoplasmic
protein.
 It is a cohesive protein.
 It is responsible for connecting the
cytoskeleton of each muscle fiber to the basal
lamina , through a protein complex containing
many subunits.

9. STRUCTURE OF DYSTROPHIN

10.  Dystrophin protein has four main functional
domains:
Actin
binding
amino
terminal
Central rod(spectrin like) domain
Cystein rich
domain
Carboxyl
terminus

11.  The dystrophin-glycoprotein complex (DGC) is
a multi subunit complex that connects the
cytoskeleton of a muscle fiber to its
surrounding extracellular matrix.
 Mutation in the DGC disrupts the complex
and leads to muscular dystrophy.

12. The dystrophin-
glycoprotein complex
consists of,
1. Dystrophin
2. Dystroglycans( and
)
3. Sarcoglycans (,,
and )
4. sarcospon
5. Syntrophins(1,1,2
,1 and 2)
6. -Dystrobrevin

14. DYSTROPHIN GENE MUTATION
1. DELETION:
o Pieces of DNA are lost
o 60-70 chance to DMD
2. DUPLICATION:
o Pieces OF DNA are copied
o 10  chance to DMD
3. POINT MUTATION:
o There are small changes in the DNA code
o 15-30 chance to DMD

15. DELETION
The deletions can described as either being “in
frame” or “out frame”
In frame: If a deletion occurs which takes out a
whole number of codons, this is referred to as an
in frame deletion.
Out frame: If the deletion takes out part of a
codon then it is said to be out of frame.

17. Methods to find deletions and
duplications:
 CGH (Comparative Genomic Hybridization Array)
 MLPA (Multiple Ligation-dependent Probe
Amplification)
 MAPH (Multiple Amplifiable Probe
Hybridization)
 SCAIP (Single Condition Amplification/ Internal
Primer)
 Multiple PCR
 Southern plot

18. Methods to find point mutations:
 Sanger gene sequence
 Resequencing array
 SCAIP
 m RNA analysis/c DNA sequencing
 FISH (Fluorescence In Situ Hybridization)