1. A doctor will look at a child’s health history and family history. The doctor will look for signs of progressive muscle weakness. 
2. During a physical exam, this doctor will look for certain symptoms. This classic pattern in boys can be highly suggestive of a DMD diagnosis:
   • Weakness in the large muscles of the legs
   • Large calf muscles
3. When suspicious of DMD, the doctor will then recommend:
   • Blood testing for muscle enzymes
   • Genetic testing
   • Muscle biopsy (less common)

This is one of the earliest tests done to diagnose DMD. It looks at the blood level of a muscle enzyme called creatinine kinase (CK). This enzyme leaks out of damaged muscle cells. It is very high in young boys with DMD. 

To confirm the diagnosis of DMD, a genetic blood test can look at a child’s DNA. This test looks for a mutation/abnormality in the DMD gene. 

New therapies can target specific mutations in the DMD gene. However, there are more than 18,000 different kinds of abnormalities that can cause this disorder. Genetic testing can help identify a child’s specific gene abnormality. It is becoming increasingly important to know your child’s mutation so your doctor can plan the best path forward for your child.

Sometimes, a muscle biopsy is used to help with diagnosis, in addition to genetic testing. In a muscle biopsy, a small piece of muscle is surgically removed for the doctors look at under the microscope. They look for evidence of muscle disease. The biopsy can also be used to measure any dystrophin in the child’s muscle. The quantity of dystrophin in the muscle can help predict how severe the disorder will be. 

Here is how doctors use dystrophin levels to understand the severity of the disease:

• Duchenne muscular dystrophy. Levels at less than 5% of the normal quantity. This is the most severe.
• “Intermediate” muscular dystrophy. Levels at 5% to 20% of the normal quantity. This is moderately severe.
• Becker muscle dystrophy. Levels at more than 20% of normal level. This is the least severe.

With the advances in genetic testing, however, muscle biopsy is rarely still used. Nearly all patients are diagnosed with genetic testing instead.

Repeating testing or imaging in older LGS patients can be useful. It can help when an underlying cause has not been determined. It can identify previously missed causes. However, it is not necessary in all cases. Sometimes, genetic testing can be reviewed rather than repeated as knowledge about genetics grows. 

Creating a treatment plan that draws on many different disciplines can help:

• Maximize a child’s functioning
• Minimize a child’s complications

Typically, a neurologist or neuromuscular specialist will be the primary doctor. They will then help plan treatment and coordinate care. 

Other specialists who may be involved include:

• Neurologists
• Orthopedists (bone specialists)
• Cardiologists
• Pulmonologists (lung specialists)
• Genetics doctors
• Physical therapists
• Occupational therapists
• Endocrinologists (hormone specialists)
• Bone health specialists 
• Dieticians

Steroids

Two steroids can help treat DMD:

• Prednisone
• Deflazacort

They may help:

• Improve muscle strength
• Improve lung and heart function
• Reduce spine abnormalities
• Keep boys with DMD walking for a longer time

Side effects are the main concern with long-term use of steroids. Side effects may include:

• Weight gain
• Short height
• Behavioral changes
• Poor bone health
• Cataracts

Exon Skipping Therapy

Recently, the FDA approved four drugs that target specific regions of the DMD gene. They can be used to treat children with specific mutations in those regions. 

All four drugs seem to increase the amount of dystrophin protein in the muscles. They seem to improve muscle strength and slow the progression of DMD. The medications have to be given through an IV every 2 weeks for life. For this reason, an infusaport is usually given to children getting this treatment. An infusaport is a small implant that allows more permanent access to a blood vein.

Future Drug Therapies

There are many other drugs currently being tested for those with DMD. These new drugs may be able to treat all patients with DMD, regardless of their specific type of gene mutation. The goal of gene therapy is to insert a normal DMD gene copy into the body’s cells. 

Heart Checkups

A complete check of the heart by a heart specialist is recommended for all boys with DMD. These checks should:

• Begin in early childhood
• Take place at least every other year until age 10 or onset of heart disease
• Take place every year after onset of heart disease

Typically, at each check, cardiologists will perform:

• An echocardiogram (ultrasound of the heart)
• An electrocardiogram (checks electrical activity of the heart)
• A physical exam

A cardiac MRI may be performed if there is concern for heart muscle damage. 

Medications

Cardiologists may also recommend starting boys with DMD on heart-protective medications. These medicines have been shown to slow the course of cardiac muscle damage in DMD. Examples are:

• Angiotensin converting enzyme (ACE) inhibitors
• Angiotensin receptor blockers (ARB)
• Beta blockers

Female DMD Carriers and Heart Disease

Female carriers of DMD are at more risk than other women of developing cardiomyopathy. In cardiomyopathy, the heart has trouble getting blood to the rest of the body. Female carriers should undergo a complete heart checkup in their late adolescence or early adulthood. They may need this checkup sooner if heart symptoms begin.

Lung Checkups

The muscles that help with breathing get weaker as DMD progresses. Pulmonologists, or lung doctors, will need to check lung function from time to time. They may do so using

• Pulmonary function tests
• Sleep studies

Pulmonary Devices

Pulmonologists may recommend different kinds of devices. These can include:

• A cough assist. A cough assist can help keep lungs clear of secretions and prevent lung infections. 
• A ventilation device. Later in the disorder, the breathing muscles get too weak to be able to work effectively. At that time, a device can assist with breathing. At first, this assistance may be needed only at night, but over time, it may become a permanent need 24 hours a day.

Noninvasive breathing support can be provided with a mask or with a nose- or mouthpiece. However, for more permanent support, a surgical opening in the windpipe may be needed. This is known as a tracheostomy.

Neuromuscular specialists can work closely with orthopedic doctors and physical and occupational therapists. These experts can provide support to:

• Keep muscles strong
• Minimize deformities of spine and limbs.

They may offer:

• Exercises. These can include stretching and strengthening exercises and working with weights.
• Braces. These can help keep limbs stretched and flexible, delaying the onset of joint problems (contractures).
• Surgery. When contractures have advanced, surgery may be performed by orthopedic doctors.
• Spine care. They will help monitor curvature of spine (scoliosis). If needed, surgery can help. 
• Supportive devices. Therapists can recommend wheelchairs, standers, walkers, lifts, shower chairs, and other mobility and transfer devices as needed.

Excessive weight gain can be a concern for boys with DMD. Weight gain can be a side effect when on steroids, and the muscle weakness of DMD can make it hard to stay active. Dieticians may recommend:

• Watching caloric intake
• Keeping a balanced diet
• Getting adequate vitamin D and calcium 

Constipation is common for those with DMD. It can be managed with:

• Good hydration
• Increased fiber intake
• Medications 

Like every other muscle in the body, the muscles involved in chewing and swallowing get weaker in later stages of DMD. This may lead to weight loss, dehydration, malnutrition, and aspiration. A swallow study can be done to make sure that a child can still swallow. If it is unsafe to eat by mouth, a feeding tube needs to be inserted directly to the stomach to provide nutrition and hydration. This is known as a gastrostomy tube (g-tube).

Some children with DMD have learning disabilities. Children should be evaluated through their school system’s special education department or at a medical center. Based on this evaluation, an individualized educational plan (IEP) can help ensure the best education possible. 

DMD is also associated with attention-deficit/hyperactivity disorder (ADHD), anxiety, and depression. Boys with DMD should be closely monitored for these disorders and provided with therapy as needed.