Children with DMD have problems in movement. Gower's sign is muscle weakness of the lower limbs in children suffering from DMD. Children use hands as a support to move up the legs to stand from the floor as a squatting position. The cause is reduced hip and thigh muscle strength. Gowers' sign in small children with DMD indicates a strong possibility of infection in the lumbar spine which makes the back weak.
Muscle atrophy is wasting away of muscles or loss of muscle tissues. During atrophy, normal muscles decrease in size and leads to weakness. The main reason of muscle loss is lack of physical activity. The biceps reduce with time in muscle atrophy. Other causes of muscle atrophy are aging, injury, malnutrition, long-term corticosteroid therapy, etc. Several diseases also result in atrophy such as multiple sclerosis, muscular dystrophy, polio, spinal muscular atrophy, etc.
Duchenne Muscular dystrophy (DMD) is caused by a mutation of the dystrophin gene. This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. With X-linked recessive mutant allele from mother, sons have 50% chance to be affected with the disease. Daughters are not affected, but they have 50% chance to be carriers like their mother.
Deletion (also called gene deletion, deficiency, or deletion mutation) is a mutation in which a part of a chromosome or a sequence of DNA is missing during DNA replication. Deletion phenomenon is also responsible among other types of mutations for Duchenne muscular dystrophy. Duchenne and Becker muscular dystrophy (DMD and BMD) are caused, in most cases, by deletions in the dystrophin gene (DMD).