Duchenne muscular dystrophy (DMD)
Duchenne Muscular Dystrophy (DMD) primarily affects boys, occurring in 1 in every 3,600 live-born boys. It is much rarer in girls, who are typically carriers of the disease. In these cases, the girls are not affected, but they carry the faulty gene in their genetic material. Around 30% of the cases develop due to some harmful environmental factors, such as ionizing radiation.
The underlying cause of the disease is the abnormal production or complete absence of a protein called dystrophin. This results in an excessive influx of calcium ions into muscle cells, leading to muscle damage and degeneration.
Signs of Degeneration
The disease is characterized by a gradual onset of muscle weakness that becomes progressively more pronounced, alongside a decline in intellectual function. In infancy children are typically asymptomatic, though some may show mild muscle weakness, and difficulty in holding up the head may be an early sign of the condition.
Children usually learn to roll over, sit up, and walk at the expected age. However, the disease typically becomes noticeable around age 3 when the muscles around the hips weaken, causing the child to stand by supporting themselves on their knees. Climbing stairs becomes difficult and their walking pattern becomes waddling. Along with these symptoms the calves often feel firmer and the child’s legs may appear unusually muscular.
As the child gets older, more muscle fibers throughout the body begin to deteriorate. The muscles in the wrists, forearms, and hands often remain functional for a while, allowing the child to eat, drink, and use a computer. Unfortunately, walking ability declines more rapidly and by around 10 years old most children will need to use a wheelchair. The primary goal is to extend the period during which the child can still walk.
Consequences of Muscle Degeneration
The symptoms of muscle weakness extend to internal organs: due to weakness in the throat and respiratory muscles, the child may have difficulty in swallowing and may cough with less force. This makes it harder for them to clear mucus from their lungs, increasing the risk of upper respiratory infections and pneumonia. Due to the weakness in bowel and bladder muscles, some children may experience difficulties with controlling their bowel movements and urination.
For children in wheelchairs, chest deformities and the progression of scoliosis further impair respiratory function. Life expectancy is largely determined by the weakness in the respiratory muscles and heart muscle. As the disease progresses, respiratory failure may occur and the child may eventually need a ventilator. In many cases the decline in intellectual function is not severe and children are able to attend regular school.
In addition to muscle weakness, joint deformities caused by muscle contractions and stiffness are also common.
Diagnose
The diagnosis is confirmed with genetic testing, which detects the absence of dystrophin as well as serum CK testing, which measures the extent of muscle damage. Normally the CK levels are below 160, but in the case of these children they can rise to tens of thousands. An electromyogram (EMG) test can also be used to measure the degree of muscle degeneration.
Fighting the Disease
The treatment for Duchenne muscular dystrophy is primarily symptomatic, aimed at improving the patient's quality of life. This is achieved through medication, physiotherapy, and sometimes surgery. It’s essential to strengthen the respiratory and back muscles, manage joint contractures and treat respiratory infections quickly, ensuring that mucus is cleared effectively from the airways. Regular ECG and chest X-ray exams are recommended to monitor the heart’s condition. Psychological support for both the child and family is also very important.
Attempts have been made to introduce muscle precursor cells from the father into the child’s muscle tissue, with the hope that healthy muscle cells will take over the functions of the damaged ones. However, the effectiveness of this method has not been proven yet.
Prevention
Prenatal diagnosis is possible, meaning that before birth a sample of amniotic fluid can be tested to determine if the fetus has inherited the disease.
The story of Kornél & Zsombor
