Question

Case study

An 8-year-old boy was presented for difficulty in walking and muscle weakness with difficulty in climbing stairs, running and particularly in vigorous physical activities, he also had decreased strength and endurance. His parents did not have consanguineous marriage, one brother and two sisters were all healthy; no other family members were similarly affected. On examination, he had difficulty jumping onto the examination table, a Gower sign, proximal weakness of pectoral and pelvic girdle muscles, a waddling gait tight hell cords, and apparently enlarged calf muscles. His serum creatine kinase and aldolase levels were 50 fold higher than normal, motor nerve conduction studies revealed low amplitude compound muscle action potentials throughout, with normal conduction velocities.

Question: How would you differentiate this disease from one of the disease listed below, which also produce muscle weakness?

Answer 1

Duchenne Muscular Dystrophy Gene (DMD) gene is the one of the largest human gene which encodes the muscle protein,dystrophin.This protein is located primarily in muscles and used for the movement of skeletal muscles and cardiac muscle.Small amounts of DMD gene are present in the nerve cells in the brain.

In skeletal muscle and cardiac muscles the dystrophin is a part of a protein complex that work together to strengthen muscle fibers and protect them from injury as they helps in contract and relax.This protein is important for the normal structure and function of synapses.

Here in the case study the 8 year old boy is presented with difficulty in walking and muscle weakness with difficulty in climbing stairsrunning and particularly in vigorous physical activities and also had decreased strength and endurance.

And on examination he had difficulty jumping onto the examination table, a Gower sign,Proximal weakness of pectoral and pelvic girdle muscles, a waddling gait tight hell cords and apparently enlarged calf muscles.

In lab studies his enzyme levels CK and aldolase were 50 fold higher than normal,

In motor nerve conduction studies reveals low amplitude compound muscle action potentials throughout with normal conduction velocities.

According to the patient symptoms and other studies shows the baby is having Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy is a rapidly progressive muscle dystophy or it is a type ofmuscular dystrophy that occurs primarily in boys.The incidence rate is approximately 1in 3500 males birth worldwide.It is caused by alteration or mutation in a gene called DMD gene or in case it often occurs in people from families without a known family history of the condition.

The symptoms of the disease usually appear the as early as infancy and before the age of 6.Due to the loss of muscle mass or wasting there is a progressive muscle weakness of the legs and pelvic muscles can be seen in this type of case.The muscle weakness can causes a waddling gait and difficulty in climbing stairs.Some range of muscle weakness can be seen in upper body part but it is not as much severe when compared with lower half of the body.

Initially the calf muscles may enlarge and eventually the enlarged muscle tissue is gradually replaced with fat and connective tissue.Usually the muscle contractures occurs in the legs

The case with DMD muscular dystrophy often have extremely elevated creatine kinase and aldolase blood levels.The creatine kinase and aldolase are enzyme that present normally in high concentrations in the muscle cells of our body.In the present condition during the process of muscle degeneration or the breakdown,that results in broken up of muscle cells and its contents will leak in to the blood stream.