There are nine major types of muscular dystrophy, though the total number of distinct subtypes runs much higher. Limb-girdle muscular dystrophy alone accounts for dozens of subtypes, each tied to a different gene mutation. The nine broad categories differ in which muscles they target first, how quickly they progress, and when symptoms appear, ranging from birth to middle age.
The Nine Major Types
The nine recognized categories are: Duchenne, Becker, myotonic, facioscapulohumeral, limb-girdle, congenital, Emery-Dreifuss, distal, and oculopharyngeal muscular dystrophy. Each involves progressive muscle weakness, but the pattern of that weakness, the age it starts, and the organs it affects beyond skeletal muscle vary significantly from one type to the next.
Duchenne and Becker
Duchenne (DMD) and Becker (BMD) muscular dystrophy are caused by mutations in the same gene, which provides instructions for making a protein called dystrophin. The critical difference is how much functional dystrophin the body can still produce. In Duchenne, the mutation prevents the body from making any functional dystrophin (less than 5% of normal levels). In Becker, the mutation results in an abnormal but partially working version (more than 20% of normal levels).
That distinction drives everything else. Duchenne appears in early childhood, typically before age 5, and progresses rapidly. Boys with DMD usually live into their twenties. Becker shows up later, often in adolescence or even adulthood, and progresses much more slowly. Males with BMD can survive into their forties or beyond. Both conditions overwhelmingly affect males. About 1 in every 5,000 males aged 5 to 9 has Duchenne or Becker, with Duchenne being three times more common.
Myotonic Dystrophy
Myotonic dystrophy is the most common form of adult-onset muscular dystrophy. It comes in two types, both caused by a segment of DNA that repeats too many times within a gene, creating instability. Type 1 results from a mutation in the DMPK gene; type 2 from a mutation in the CNBP gene.
The two types affect different muscle groups. Type 1 primarily weakens muscles farthest from the center of the body: lower legs, hands, neck, and face. Type 2 targets muscles closer to the trunk: neck, shoulders, elbows, and hips. Type 2 tends to be milder overall. Symptoms for both commonly develop in a person’s twenties or thirties, though they can appear at any age. A mild form of type 1 may not become noticeable until mid to late adulthood. The hallmark symptom that sets myotonic dystrophy apart from other forms is myotonia, a prolonged stiffness after contracting a muscle (for example, difficulty releasing your grip after shaking hands).
Facioscapulohumeral Dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) follows a distinctive top-down pattern. Weakness in the facial muscles or shoulders is usually the first sign. Over time, it can spread to the lower legs, hips, and pelvis. The progression is slow, unfolding over decades rather than years.
Weak lower leg muscles can cause foot drop, making it harder to walk and increasing fall risk. Weak hip and pelvic muscles make climbing stairs difficult. Weak abdominal muscles can lead to an exaggerated curve in the lower back. About 20% of people with FSHD eventually need a wheelchair, but the majority do not.
Limb-Girdle Dystrophy
Limb-girdle muscular dystrophy (LGMD) is not a single disease but an umbrella category. It covers any muscular dystrophy that primarily weakens the muscles around the hips and shoulders (the “limb girdles”). Dozens of different genes have been identified as causes, each producing a distinct subtype. Some subtypes begin in childhood, others in adulthood. Some progress quickly, others slowly. What unites them is the location of the weakness: the upper legs, hips, shoulders, and upper arms are hit first and hardest.
Congenital Muscular Dystrophy
Congenital muscular dystrophy (CMD) refers to a group of forms that become apparent at or near birth. Several subtypes exist, and many affect more than just muscle.
- Laminin-alpha 2-related (LAMA2): Accounts for 10% to 37% of CMD cases. Children with the early-onset form often never develop the ability to walk. Seizures affect about one-third of them.
- Dystroglycanopathies: Make up 12% to 25% of cases. These frequently affect the brain, causing seizures and cognitive disabilities, and can also cause eye problems. Walker-Warburg syndrome and muscle-eye-brain disease fall into this group.
- Collagen VI-related: Represent 12% to 19% of cases. Severity ranges from mild (Bethlem muscular dystrophy) to severe (Ullrich congenital muscular dystrophy).
- Selenoprotein N-related: About 11% of cases. These primarily weaken the head and trunk muscles early in life.
Depending on the specific subtype, children with CMD may also develop eye conditions like nearsightedness or glaucoma, brain malformations, or drooping eyelids.
Emery-Dreifuss Dystrophy
Emery-Dreifuss muscular dystrophy stands out because of its impact on the heart. Almost all people with this condition develop heart problems by adulthood, including abnormal heart rhythms and defects in the electrical signals that control the heartbeat. Left untreated, these can cause palpitations, an unusually slow heart rate, fainting, heart failure, and an increased risk of sudden death. A small percentage of people with the autosomal dominant form experience heart problems without any noticeable muscle weakness at all.
The skeletal muscle symptoms are real but often less prominent than the cardiac risk. Joint contractures (tightening that limits range of motion) in the elbows, ankles, and neck are common early signs. Female carriers of certain forms may develop heart problems or mild muscle weakness even without the full condition.
Oculopharyngeal Dystrophy
Oculopharyngeal muscular dystrophy (OPMD) targets two specific areas: the eyelids and the throat. The most common symptoms, in order of frequency, are drooping eyelids, difficulty swallowing, tongue weakness or shrinkage, limited upward eye movement, difficulty speaking, and facial weakness. Over time, weakness can spread to muscles around the hips, shoulders, and upper legs.
The most serious complication is swallowing difficulty. Weak tongue and throat muscles raise the risk of choking, aspiration pneumonia (when food or liquid enters the lungs), and malnutrition.
Distal Muscular Dystrophy
Distal muscular dystrophy is another umbrella term, covering several rare forms that primarily weaken the muscles farthest from the body’s center: the hands, forearms, lower legs, and feet. These forms tend to progress more slowly than many other types and typically appear in adulthood. Because they affect the extremities first, early symptoms often show up as difficulty with grip strength or frequent tripping.
How Muscular Dystrophy Is Diagnosed
Diagnosis typically starts with a blood test measuring creatine kinase (CK), an enzyme that leaks out of damaged muscle cells. In children with Duchenne, CK levels peak at 10 to 20 times the normal upper limit by age 2, then gradually decline by about 25% per year as muscle mass is lost.
Genetic testing is the definitive step. For Duchenne and Becker, the analysis looks for large deletions or duplications in the dystrophin gene, which account for 70% to 80% of cases. If those aren’t found, next-generation sequencing searches for smaller mutations. In many cases today, next-generation sequencing is the first test performed. If genetic testing comes back negative but suspicion remains high, a muscle biopsy can measure how much dystrophin protein the tissue actually contains. The same genetic testing approach, adapted for different genes, applies across the other types of muscular dystrophy as well.