Duchenne Muscular Dystophy

Introduction• Commonly referred to as DMD• The disease was first described by the Neapolitan physician

Giovanni Semmola in 1834 and Gaetano Conte in 1836• DMD is named after the French neurologist Guillaume

Benjamin Amand Duchenne • Duchenne was the first who did a biopsy to obtain tissue

from a living patient for microscopic examination.

Inheritance

• Caused by an absense of dystrophin

• Dystrophin is a protein that helps keep muscle cells intact

• DMD has x-linked recessive inheritance pattern

• Passed on by the mother• Not all children of a carrier

will get the disease• 80% of carriers of DMD do

not have any signs or symptoms of the disease

• Females who carry the changed copy of the gene have a 50% chance of passing it on

• 25% of having a child with DMD if the mom is a carrier

• DMD affects 1 out of 3,500 male births worldwide

Duchenne Muscular Dystrophy• DMD is one of nine muscle dystrophies • Causes muscle weakness that can begin as early as three years old• The muscle weakness starts in the hip muscles and then spreads

to the pelvic, thigh, and shoulder areas• DMD is life-threatening and most cases of DMD die at age 30• Externally a person with DMD looks abnormally skinny and fragile• Internally the affected person’s muscles are much smaller than

those of an unaffected person

Treatment

• Treatment for DMD is aimed at the symptoms• Aggressive management of dilated cardiomyopathy with anti-

congestive medications is used • In severe cases cardiac transplantation is used• Assistive devices for respiratory complications may be needed• The steroid prednisone is given to patients with DMD to improve

the strength and function of the individuals• Prednisone has also shown to prolong the ability to walk by 2 to 5

years• Physical therapy is used to promote mobility and prevent

contractures • Surgery may be needed for severe contractures and scoliosis• Several other therapies are under investigation such as coenzyme

Q10, glutamine, pentoxifyline, and PTC124

Detection• 20% of carriers of DMD will show symptoms including muscle

weakness and cardiac abnormalities• A clinical diagnosis may be made when a boy has progressive

symmetrical muscle weakness • The symptoms present before age 5 years, and they often have

extremely elevated creatine kinase blood levels • If untreated, the affected boys become wheelchair dependent

before age 13 years• A muscle biopsy (taking a sample of muscle) for dystrophin studies

can be done to look for abnormal levels of dystrophin in the muscle • The dystrophin protein can be visualized by staining the muscle

sample with a special dye that allows you to see the dystrophin protein

Citations

• http://mda.org/disease/duchenne-muscular-dystrophy• http://mda.org/disease/duchenne-muscular-dystrophy• http://www.genome.gov/19518854