Biology

Muscular dystrophy refers to a group of more than 30 hereditarydiseases of the muscular system characterized by weakness and wasting of skeletalmuscles. One of these diseases that belong to this group is Duchenne muscular dystrophy (DMD). This is a severe recessive X-linked form of  Muscular dystrophy muscular dystrophy characterized by rapid progression of muscle degeneration, eventually leading to loss of ambulation and death. It is named after the French Guillaume Duchenne Guillaume Benjamin Amand Duchenne (18061875), who first described the disease in 1861. Because of the X-linked inheritance pattern, this disease almost exclusively affects males, but females can be carriers. It is by far the most common childhood-onset muscular dystrophy, afflicting 1 in 3300 boys with an overall prevalence of 63 cases per million and manifests in patients aged three to seven years old with the development of lordosis, a waddling gait, and the Gowers sign - pushing on the knees in order to stand.

This disease involves the DMD or Duchenne gene. This gene provides instructions for making dystrophin, a rod-shaped  Cytoplasmic cytoplasmic  Protein protein, and a vital part of a  Protein complex protein complex that connects the  Cytoskeleton cytoskeleton of a  Muscle fiber muscle fiber to the surrounding  Extracellular matrix extracellular matrix through the  Cell membrane cell membrane.. Dystrophin is located chiefly in muscles used for movement (skeletal muscles) and the muscles of the heart (cardiac muscles), but it can also be found in the brain and other smooth muscles. It is part of a group of proteins that work together that strengthens muscle fibers and protects them from injury as muscles contract and relax. The dystrophin complex may also play a role in cell signaling by interacting with proteins that send and receive chemical signals.

Mutations of the said gene causes the deletion of its parts while other mutations abnormally duplicate part of the genes or change a small number of DNA building blocks in the gene. This means that these mutations alter the normal nucleotide sequences of this proteins gene and stop its synthesis. The absence of Dystrophin dystrophin permits excess  Calcium calcium to penetrate the  Sarcolemma sarcolemma (cell membrane). In a complex cascading process that involves several pathways and is not clearly understood, increased  Oxidative stress oxidative stress within the cell damages Sarcolemma sarcolemma, and eventually results in the death of the cell. Muscle fibers undergo Necrosis necrosis and are ultimately replaced with  Adipose adipose and  Connective tissue connective tissue. Without it, the cell membrane becomes permeable, so that extracellular components enter the cell, increasing the internal pressure until the muscle cell explodes and dies. Muscles are susceptible to mechanical injury and undergo repeated cycles of necrosis and regeneration. Ultimately, regenerative capabilities are exhausted or inactivated.

Skeletal muscles become damaged as they repeatedly contract and relax with use so they die over time, causing the characteristic of weakness and wasting especially of the muscles of the hips, pelvic area, thighs and shoulders Because of this, a boy with this disease will have problems in his early developmental milestones such as sitting and walking,  As he grows older, he will have more and more difficulty in walking and will probably use a wheelchair on a regular basis.

Since dystrophin can also be found in the muscles of the heart and in smooth muscles, life-threatening heart and respiratory conditions become more prevalent as this disorder progresses. Complications like shortness of breath, fluid in the lungs, and swelling in the feet and lower legs can be seen.