Becker muscular dystrophy: symptoms, diagnosis and monitoring

Duchenne and Becker are best thought of as two ends of a range produced by one gene. In Duchenne the changes disrupt the way the gene is read, so almost no dystrophin is made. In Becker the reading frame is usually kept intact, so a shortened version of the protein is produced. It does some of its job, which is why the muscles survive for longer.

The practical result is that some boys who start with a Becker label have a presentation close to Duchenne, and some adults are diagnosed only in their thirties or later after a long period of being told they were simply unfit. Specialists sometimes talk about intermediate forms between the two.

The first symptom is often difficulty keeping up with other children at sport, cramping after exercise, or muscle pain rather than outright weakness. Calf enlargement is common. Weakness tends to start in the thighs, hips and shoulders and spreads gradually. Some people remain walking well into adult life, while others lose the ability earlier.

The NHS lists muscle weakness that gets worse with age, frequent falls, muscle discomfort and joint stiffness among general features of muscular dystrophy, and these descriptions fit many people with Becker.

• Muscle cramps or pain with exercise

• Thigh and hip weakness causing difficulty on stairs

• Calf enlargement

• Toe walking or shortened Achilles tendons

• Raised blood creatine kinase, sometimes found incidentally

A GP or paediatrician will usually start with a creatine kinase blood test and a neurological examination. The NHS lists blood tests, genetic screening, electromyography, muscle biopsy and MRI as the main tools used for muscular dystrophy, and genetic testing of the DMD gene is now the central step for Becker.

Identifying the exact DMD change is useful beyond the label. It confirms whether the pattern fits Becker rather than a limb-girdle dystrophy that looks similar, it helps predict how the heart might be affected, and it allows relatives to be offered carrier testing. NHS genetic testing is free when arranged by a hospital specialist.

In Becker, heart involvement can progress independently of how strong the legs are. A man who walks comfortably can still develop an enlarged, weakened heart. MedlinePlus notes that cardiomyopathy typically begins in adolescence in both Duchenne and Becker and can progress to dilated cardiomyopathy, a potentially life-threatening condition.

For that reason, people with Becker are generally offered regular cardiology review with echocardiography or cardiac MRI and heart-rhythm assessment even when they feel well. Medicines that protect the heart muscle may be started early. Breathlessness, ankle swelling, palpitations or fainting should prompt prompt medical review, and sudden chest pain, collapse or severe breathlessness needs 999.

Management is built around keeping people active safely. Gentle regular exercise and physiotherapy are usually encouraged, whereas very heavy resistance training or exhausting exertion is avoided because it can aggravate muscle damage. Occupational therapy, appropriate footwear or orthoses and adaptations at work can postpone loss of independence.

The NHS notes that care may include medicines, surgery for complications and respiratory support when needed, and that specialist teams give individual outlook. Some people with Becker eventually need a wheelchair, and a smaller number need breathing support at night. Anaesthesia needs advance planning because muscle conditions can carry extra risk, so any hospital team should be told about the diagnosis before procedures.

Because the gene is on the X chromosome, the pattern in a family is that men are affected and women may be carriers. Carriers can have mild muscle symptoms or heart changes, so Action Duchenne's comments about cardiac care in carriers are relevant to Becker families too.

Clinical genetics can explain recurrence risk, carrier testing and reproductive options. Genetic counselling is offered alongside NHS testing and covers the practical and emotional consequences of sharing results with relatives.