Are You A Pediatrician? Take This Quiz About Muscular Dystrophy In Children

Explanation
A neuromuscular disease could be suspected in a pregnancy complicated by polyhydramnios and reduced foetal movement. Neonates or infants may present with arthrogryposis, hypotonia, early feeding difficulties, respiratory problems or a need for respiratory support in the absence of any significant pulmonary pathology. Toe-walking or global developmental delay may manifest later in childhood.

Explanation
The statement is true because Duchenne and Becker muscular dystrophies are indeed the most common pediatric muscular dystrophies. These are genetic disorders that primarily affect the muscles, causing progressive muscle weakness and degeneration. Duchenne muscular dystrophy is more severe and typically appears in early childhood, while Becker muscular dystrophy is milder and usually manifests in adolescence or early adulthood. Both conditions primarily affect boys and are caused by mutations in the dystrophin gene.

Explanation
Duchenne and Becker muscular dystrophies are both caused by mutations in the dystrophin gene, which is located on the X chromosome. Since these conditions are X-linked recessive, they primarily affect males. Females can be carriers of the mutated gene but usually do not show symptoms. Therefore, the statement that Duchenne and Becker muscular dystrophies have an X-linked recessive mode of inheritance is true.

Explanation
To date, there is no specific treatment for inherited neuromuscular conditions.
The prospects of genetic therapy has been very disappointing, hampered by various challenges of finding effective delivery systems and poor clinical responses.

Explanation
Pregnancy with a foetus with muscular dystrophy can be complicated by polyhydramnios, which is an excessive accumulation of amniotic fluid. This can occur due to the impaired swallowing and movement of the foetus. Additionally, reduced foetal movement is also a common symptom of muscular dystrophy. Therefore, it is true that pregnancy with a foetus with muscular dystrophy may be complicated by polyhydramnios and reduced foetal movement.

Explanation
Children with muscular dystrophy may present later in childhood with toe walking or global developmental delay. This means that these symptoms may not be evident in the early stages of childhood but may become apparent as the child grows older. Therefore, the statement "True" is correct.

Explanation
The given statement is true. DNA analysis in Duchenne or Becker muscular dystrophy reveals a deletion or duplication in the dystrophin gene. This genetic analysis is a reliable method for diagnosing these types of muscular dystrophy. The absence or alteration of the dystrophin gene is a key characteristic of these conditions, which affects muscle function and leads to progressive muscle weakness.

Explanation
The analysis of muscle biopsy can indeed include various techniques such as haematoxylin and eosin staining, fibre typing, immunohistochemistry, oxidative enzyme staining, immunoblotting, enzyme analysis, mitochondrial DNA analysis, and electron microscopy. These techniques are commonly used to examine the structure, composition, and function of muscle tissue, and can provide valuable information for diagnosing and understanding various muscle-related disorders. Therefore, the statement "Analysis of muscle biopsy may include" is true.

Explanation
EMG may show a clear myopathic or denervating pattern, but the picture is often mixed.

Explanation
Muscle ultrasound is a useful tool for detecting myopathies and muscular dystrophies because it can identify increased echogenicity in the affected muscles. Echogenicity refers to the ability of a tissue to reflect ultrasound waves, and increased echogenicity indicates abnormalities or changes in the muscle structure. Therefore, the statement that muscle ultrasound can be valuable in detecting myopathies and muscular dystrophies, associated with increased echogenicity of involved muscles, is true.

Explanation
MRI can help to identify the pattern of muscle groups involved in muscle dystrophy. This imaging technique can provide detailed images of the muscles, allowing doctors to assess the extent and distribution of muscle damage. By analyzing these images, they can identify the specific muscle groups affected by muscle dystrophy and monitor the progression of the disease. Therefore, the statement that MRI cannot help to identify the pattern of muscle groups involved in muscle dystrophy is false.

Explanation
The characteristic findings of dystrophic changes on muscle biopsy include: variation in fibre size, fibre splitting, necrotic fibres, excess of fatty and fibrous tissue

Explanation
The statement is true because classification of childhood muscular dystrophy can indeed be done at the level of the specific protein deficiency by immunohistochemistry and immunoblotting. These techniques allow for the identification and analysis of proteins that may be deficient or abnormal in individuals with muscular dystrophy. Additionally, classification can also be done at the DNA level through mutation analysis, which involves analyzing the genetic material for any mutations or abnormalities that may be causing the muscular dystrophy.

Explanation
A deletion mutation of one or more exons of the dystrophin gene is found in 65% of males with dystrophinopathy. This means that a significant majority of males with this condition have this specific type of mutation.

Explanation
The given statement is true. It states that about 5% of males with dystrophinopathy have a duplication of one or more exons of the gene, while 30% have point mutations. This means that a small percentage of males with dystrophinopathy have a duplication of certain parts of the gene, while a larger percentage have point mutations, which are changes in individual nucleotides within the gene sequence.

Explanation
Approximately one-thirds of the dystrophin gene mutations are new mutations.

Explanation
The clinical phenotype of muscular dystrophy is indeed dependent on the amount of functional dystrophin present in the muscles. Dystrophin is a protein that plays a crucial role in maintaining the structural integrity of muscle fibers. In individuals with muscular dystrophy, a genetic mutation results in the absence or reduced levels of dystrophin, leading to muscle weakness and degeneration. The severity of the symptoms and the age of onset can vary depending on the amount of functional dystrophin present. Therefore, it is true that the clinical phenotype of muscular dystrophy is influenced by the amount of functional dystrophin in the muscles.

Explanation
18. The clinical phenotype of dystrophinopathy is very wide and includes asymptomatic cases with elevated creatine kinase (CK) only, cases with cramps and myalgia, cases with dilated cardiomyopathy and no skeletal muscle involvement.

Explanation
Approximately 17% of female carriers exhibit observable muscle weakness. This suggests that there is a significant proportion of female carriers who experience this particular symptom.

Explanation
The statement is true because boys with the more severe Duchenne phenotype have a complete absence of dystrophin, which is a protein that helps maintain the structure of muscle fibers. On the other hand, males with the milder Becker phenotype have a partial deficiency of dystrophin, meaning that they still have some of the protein present, although it may be reduced in quantity or function. This difference in the level of dystrophin deficiency contributes to the variation in the severity of symptoms between the two phenotypes.

Explanation
Approximately 8% of female carriers exhibit signs of dilated cardiomyopathy, a condition characterized by the enlargement of the heart chambers, along with or without muscle weakness. This suggests that there is a significant proportion of female carriers who may be at risk of developing this cardiac disorder.

Explanation
Duchenne's disease is a progressive genetic disorder that primarily affects males. It causes muscle weakness and degeneration, leading to immobility. The disease typically starts to manifest in early childhood and progresses rapidly. By the age of 13, most patients become immobile due to severe muscle weakness. Unfortunately, the condition is life-threatening, and the majority of individuals with Duchenne's disease do not survive beyond their mid-20s. Therefore, the statement that most patients with Duchenne's disease become immobile before the age of 13 years and usually die before 25 years is true.

Explanation
Most patients with Becker's type of disease have a milder form of the condition and are able to walk independently (ambulant) until their forties or even later. This suggests that the disease progression is slower and individuals with Becker's type have a better prognosis compared to other types of the disease.

Explanation
Patients with muscular dystrophy often experience weakness and deterioration of respiratory muscles, leading to respiratory infections and insufficiency. This is because the muscles responsible for breathing become weakened over time, making it difficult for patients to effectively clear their airways and cough out mucus, increasing the risk of infections. Additionally, the weakened respiratory muscles can result in insufficient oxygen intake, leading to respiratory failure. Cardiac failure is also a common cause of death in muscular dystrophy patients, as the disease can affect the heart muscles, leading to heart failure.

Explanation
Dystrophin is a 427 kDa protein, consisting of an N-terminal domain and a central rod domain - which binds actin with the greatest affinity, a cysteine rich domain, and a C-terminal globular domain, which bind to the trans-membrane dystroglycan complex.

Explanation
The correct answer includes multiple clinical complications of muscular dystrophy in childhood. These complications are dilated cardiomyopathy, rhabdomyolysis and acute renal failure, tachyphylaxis to depolarising neuromuscular blocking drugs, nocturnal hypoventilation desaturation during REM sleep, and kyphoscoliosis. These complications can all occur as a result of the progressive muscle weakness and degeneration seen in muscular dystrophy. Dilated cardiomyopathy refers to the enlargement and weakening of the heart muscle, while rhabdomyolysis is the breakdown of muscle tissue leading to kidney damage. Tachyphylaxis to depolarising neuromuscular blocking drugs refers to a reduced response to these medications, which are commonly used during surgeries. Nocturnal hypoventilation desaturation during REM sleep is a breathing disorder that can lead to low oxygen levels during sleep, and kyphoscoliosis is an abnormal curvature of the spine.

Explanation
The statement is true because muscular dystrophy, a genetic disorder that weakens and deteriorates the muscles over time, can lead to various complications in childhood. These complications may include learning disabilities, malnutrition, muscle contractures, squint, depression or anxiety disorders, and respiratory insufficiency.

Explanation
The statement is true because muscular dystrophy is a complex condition that affects various systems in the body. Therefore, a multidisciplinary team is required to manage the different aspects of the disease. Each specialist plays a crucial role in providing comprehensive care to children with muscular dystrophy. The team includes paediatricians for overall medical management, ophthalmologists for eye-related issues, neurosurgeons for any neurological complications, orthopaedic surgeons for musculoskeletal problems, cardiologists for heart-related concerns, clinical geneticists for genetic counseling and testing, psychiatrists and psychologists for mental health support, social workers for assistance with social and emotional needs, and physiotherapists and occupational therapists for rehabilitation and improving quality of life.