Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD, also known as Duchenne‑type muscular dystrophy) is an X‑linked recessive congenital disorder caused by a mutation in the gene encoding the protein dystrophin. It is named after the French neurologist Guillaume Duchenne de Boulogne. DMD is a fatal, currently incurable disease that clinically manifests in boys. It is the most common form of muscular dystrophy, with an incidence of approximately 1 per 3,500 live‑born boys.

Symptoms

DMD is characterized by progressive muscle weakness, initially affecting the legs and pelvic muscles and later spreading to the upper limbs, neck, and respiratory muscles. By approximately 13 years of age, boys become wheelchair‑dependent. Death usually occurs between 20 and 30 years of age as a result of cardiac or respiratory failure.

Girls are predominantly asymptomatic carriers and usually have no symptoms or only very mild ones; however, a few cases are known in which girls exhibited typical features of DMD or BMD.

Becker muscular dystrophy (BMD) is a milder allelic form of the disease with a slower progression and longer survival. The phenotype covers a very broad spectrum, ranging from very mild involvement—where patients are followed only on an outpatient basis throughout life—to forms with a course similar to DMD. Clinical symptoms usually appear after the fifth year of life. The mildest forms of BMD are characterized only by muscle pain, cramps, or myoglobinuria after physical exertion.

Diagnosis

DMD is caused by a mutation on the X chromosome in the gene encoding dystrophin. In patients with DMD, dystrophin is completely absent, whereas in patients with BMD a mutated dystrophin is present. The dystrophin gene is the largest known human gene, which explains the high probability of mutations occurring within it. This accounts for the large number of DMD cases arising from spontaneous (de novo) mutations without a family history of the disease.

• svalová ochabnutosť
• od približne 13. roku pripútanosť na vozík
• smrť nastáva medzi 20-30 rokom ako dôsledok srdcovej alebo dychovej nedostatočnosti
• dievčatá majú minimálne ťažkosti (len veľmi málo známych prípadov, keď mali typické príznaky DMD)
• klinické príznaky až po piatok roku dieťaťa