Duchenne muscular dystrophy is a genetic condition characterized by progressive muscle weakness and defects in muscle proteins. It is caused by an absence of the dystrophin protein due to mutations in the DMD gene located on the X chromosome. This weakens the connection between muscle proteins and cell membranes, allowing calcium to enter cells and cause muscle fiber damage and wasting. Symptoms begin in childhood and include difficulty walking, joint contractures, and cardiac issues. Diagnosis involves muscle biopsies, genetic testing, and elevated muscle enzyme levels. It primarily affects boys and is the most common and severe form of muscular dystrophy.

1. Midhun Paul
Monalisa
Simson

2. WHAT IS DUCHENNE MUSCULAR
DYSTROPHY?
DUCHENNE MUSCULAR DYSTROPHY IS A
GENETIC OR HEREDITARY MUSCLE CONDITION;
CHARACTERIZED BY PROGRESSIVE SKELETAL
MUSCLE WEAKNESS, DEFECTS IN MUSCLE
PROTEINS, AND THE DEATH OF MUSCLE CELLS
AND TISSUE.

3. FUNCTION OF DYSTROPHIN
Dystrophin provides strength to muscle cells
by linking the internal cytoskeleton to the
surface membrane.
Without this structural support, the cell
membrane becomes permeable. As
components from outside the cell are allowed
to enter the internal pressure of the cell
increases until the cell bursts and dies.

4. HOW MUSCULAR DYSTROPHY IS CAUSED?????
 In DMD, absence of the dystrophin protein weakens the
connections between all of the proteins in the muscle and the cell
membrane.
 Eventually the cell membrane becomes weaker and ruptures.
 As a result, particles, such as calcium, can move in and out of
the ruptured cell membrane.
 As calcium moves into the muscle cell, it will cause contraction at
the damaged site and muscle fibers will break. When this is
severe enough, the muscle will begin to waste away
It is due to mutation of a gene, responsible for
production of dystrophin

5.  The DMD gene
is located on
the Xp 21 band
of the X
chromosome
 Mutations
leading to the
absence of
dystrophin
WHERE IS THIS GENE??????

6. DUCHENNE MUSCULAR DYSTROPHY INHERITANCE
During the translocation process, a mutation
occurs.
Mutations leading to the absence of dystrophin
Very Large Deletions (lead to absence of dystrophin)
Mutations causing reading errors (causes a degraded,
low functioning DMD protein molecule)
Stop mutation
Splicing mutation
Duplication
Deletion
Point Mutation

7. TO WHOM IT WILL BE EFFECTED
 Mother carries the recessive gene and
passes it to her child
 Trait is usually expressed in
males only

9. WHAT ARE THE SYMPTOMS????
• Muscle weakness
• Delayed development of muscle motor skills
• Problems walking (delayed walking)
• Difficulty using one or more muscle groups
(depends on the type of dystrophy)
• Eyelid drooping (ptosis)
• Drooling
• Hypotonia
• Mental retardation ( only present in some types of
MD)
• Joint contractures (clubfoot, clawhand or others)

10. • Onset : age 3-6
years
• Progressive
weakness
• Pseudohypertrop
hy of calf
muscles
• Spinal deformity
• Cardiopulmonary
involvement
Mild - moderate MR
DMD: Clinical manifestation

11. Pseudohypertrhophy of calf muscle, Tip toe gait
forward tilt of pelvis, compensatory lordosis

12. Laboratory Test
Muscle biopsy: the primary test used to confirm the diagnosis.
DNA test
Serum CPK (creatine phosphokinase-an enzyme found in muscle)
may be elevated.
EMG (electromyography) may confirm that weakness is caused by
destruction of muscle tissue rather than damage to nerves.
ECG (electrocardiography) to monitor changes in cardiac status
Myoglobin - urine/ serum: When muscle is damaged, the myoglobin is
released into the bloodstream. It is filtered out of the bloodstream by
the kidneys, and eliminated in urine. In large quantities, myoglobin can
damage the kidney and break down into toxic compounds, causing
kidney failure.

13. LABORATORY DIAGNOSIS
LDH: LDH is most often measured to evaluate the presence
of tissue damage. The enzyme LDH is in many body
tissues, especially the heart, liver, kidney, skeletal
muscle, brain, blood cells, and lungs.
Creatinine : A normal (usual) value is 0.8 to 1.4
mg/dl. Creatinine is a breakdown product of creatine,
which is an important constituent of muscle. A serum
creatinine test measures the amount of creatinine in
the blood. Greater-than-normal levels may indicate:
Muscular dystrophy. Lower-than-normal levels may
indicate: Muscular dystrophy (late stage)
AST: The normal range is 10 to 34 IU/L. An increase has
many indications, one of them being progressive MD.

14. FACTS ABOUT MUSCULAR DYSTROPHY
DMD affects mostly males at a rate of 1 in 3,500
births.
 There are over 200 types of mutations that can
cause any one of the forms of muscular dystrophy.
 DMD is the most severe and common type of
muscular dystrophy.
 DMD is characterized by the wasting away of
muscles.
 DMD is the most aggressive form of muscular
dystrophy.
 Diagnosis in boys usually occurs between 16
months and 8 years.
Parents are usually the first to notice problem.
 Death from DMD usually occurs by age of 30