Diagnostics of Duchenne muscular dystrophy - analysis of 1 or 2 individually selected point mutations of the DMD gene

Diagnosis of Duchenne'a muscular dystrophy - analysis of 1 or 2 individually selected point mutations in the DMD gene

Clinical significance

Duchenne'a and Becker muscular dystrophies are associated with recessive inheritance coupled to the X chromosome. These forms of muscular dystrophy occur almost exclusively in men. More than 2,000 mutations in the DMD gene have been identified in people with Duchenne'a and Becker muscular dystrophy. These conditions occur almost exclusively in men and are characterized by progressive muscle weakness and atrophy and dilated cardiomyopathy. Most mutations delete a fragment of the DMD gene. Other mutations abnormally duplicate part of the gene or alter a small number of nucleotidesóin the gene. Mutations that cause Becker muscular dystrophy, whichóra usually has milder features and appears at a later age than Duchenne muscular dystrophy'a, usually lead to an abnormal version of dystrophin thatóra retains some function. Mutations thatóre causing more severe Duchenne'a muscular dystrophy produce non-functional dystrophin. Skeletal muscle and cardiac muscle cells without functional dystrophin become damaged, weaken and die over time, causing the characteristic muscle weakness and heart problems seen in Duchenne'a and Becker muscular dystrophy. Duchenne'a and Becker muscular dystrophies have similar symptoms and are caused by róely mutations in the same gene. In boysów with Duchenne muscular dystrophy'a, muscle weakness appears in early childhood and worsens rapidly. Affected children may have opóed motor skills such as sitting, standing and walking. Signs and symptoms of Becker muscular dystrophy tend to be milder and more orchestrated. In most cases, muscle weakness becomes apparent póously in childhood or adolescence and worsens much more slowly. Both forms of Duchenne'a and Becker muscular dystrophy are associated with a heart condition called cardiomyopathy, whichóra weakens the heart muscle, preventing the heart from pumping blood efficiently. Duchenne'a and Becker muscular dystrophies together affect 1 in 3,500 to 5,000 newborn boysów worldwide.

Patient preparation

Material: EDTA blood

Interventions

The basis for detecting genetic changes by molecular biology methods is the amplification of the patient's genetic material by polymerase chain reaction (PCR). Note that someóre drugs inhibit the PCR reaction, making it difficult or impossible to perform the test. These drugsów include someóre anticoagulants (e.g., heparin) and antiviral drugs (e.g., acyclovir). If the patient is taking drugs that inhibit PCR or preparations with unknown effects on PCR, blood should be drawn when the plasma concentrations of these drugsóre relatively lowest, such as just before the next dose. Drugs taken by the patient with potential inhibitory effects on PCR should be noted on the referral form. If in doubt, contact the Laboratory