muscular dystrophy-dystroglycanopathy type B

Muscular dystrophy-dystroglycanopathy type B (MDDGB) refers to a group of congenital muscular dystrophies characterized by early onset muscle weakness, often before walking, along with mild intellectual disability and brain anomalies [4]. This condition is part of a larger group of disorders known as "dystroglycanopathies," which result from defective glycosylation of alpha-dystroglycan (DAG1; 128239) [2].

The clinical features of MDDGB include:

• Myopathic facies
• Elevated circulating creatine kinase concentration
• Decreased fetal movement
• Prolonged QT interval
• Feeding difficulties [5]

MDDGB is an autosomal recessive congenital muscular dystrophy, meaning that it is inherited in an autosomal recessive pattern. This means that a person must inherit two copies of the mutated gene (one from each parent) to develop the condition.

There are several subtypes of MDDGB, including type B1, which is caused by mutations in the POMT1 gene [1]. Other subtypes, such as MDDGB14 and MDDGB2, have been identified and are characterized by severe muscle weakness apparent in infancy and impaired intellectual development [13][11].

Overall, muscular dystrophy-dystroglycanopathy type B is a rare and serious condition that affects muscle strength and cognitive function. It is essential for early diagnosis and treatment to manage the symptoms and improve quality of life.

References: [1] - #1 [2] - #2 [4] - #4 [5] - #5 [11] - #11 [13] - #13

Muscular dystrophy-dystroglycanopathy type B, also known as congenital muscular dystrophy-dystroglycanopathies with or without impaired intellectual development (type B), is a condition that affects the muscles and can be associated with intellectual disability.

Common symptoms:

• Feeding difficulties
• Joint and spinal deformities
• Respiratory insufficiency
• Ocular anomalies, such as strabismus, retinal dystrophy, or oculomotor apraxia

These symptoms may vary in severity and can be present at birth or develop later in life. In some cases, the condition may also be associated with impaired intellectual development.

Other possible symptoms:

• Muscle weakness
• Muscle stiffness or looseness
• Spinal deformities
• Respiratory problems
• Ocular anomalies

It's worth noting that the severity and progression of muscular dystrophy-dystroglycanopathy type B can vary significantly from person to person, even within the same family.

References:

• [5] Congenital muscular dystrophy-dystroglycanopathies with or without impaired intellectual development (type B)
• [6] Feeding difficulties, joint and spinal deformities, and respiratory insufficiency may be associated. Decreased alpha-dystroglycan on immunohistochemical muscle
• [13] At least 18 causative genes of dystroglycanopathy have been identified, and its clinical symptoms are diverse, ranging from severe congenital to adult-onset limb-girdle types.
• [14] Signs and symptoms of muscular dystrophy vary depending the type. Symptoms of Duchenne and Becker muscular dystrophy include: Weakness that starts in the trunk and spreads to the arms and legs Legs usually weaken first, making it hard to run, jump, or climb stairs; Abnormal curves in the spine ; Heart and lung problems; Mental problems in some ...

Diagnostic Tests for Muscular Dystrophy-Dystroglycanopathy Type B

Muscular dystrophy-dystroglycanopathy type B is a congenital muscular dystrophy characterized by severe muscle weakness in infancy and impaired intellectual development. The diagnostic tests for this condition are crucial for early detection, accurate diagnosis, and effective management.

Important Diagnostic Tools:

• CK level: A blood test that measures the level of creatine kinase (CK) enzyme in the blood, which is elevated in muscular dystrophy-dystroglycanopathy type B.
• Nerve conduction study: A test that evaluates the electrical activity of nerves and can help diagnose neurogenic involvement.
• EMG with or without repetitive nerve stimulation: An electromyogram (EMG) test that records the electrical activity of muscles, which can help identify muscle damage.
• Brain MRI: A magnetic resonance imaging (MRI) scan of the brain to rule out other conditions and assess for structural abnormalities.
• Muscle biopsy: A surgical procedure where a small sample of muscle tissue is removed and examined under a microscope to confirm the diagnosis.

Additional Diagnostic Tools:

• Genetic testing: Testing of genes such as POMT1, which can help confirm a clinical diagnosis, predict disease prognosis and progression, facilitate early detection of symptoms, inform family planning and genetic counseling, or promote enrollment in clinical trials.
• Muscle imaging studies: Imaging tests that evaluate muscle structure and function, such as ultrasound or MRI scans.

Clinical Considerations:

• The geographic and ethnic backgrounds, clinical features, brain imaging studies, muscle imaging studies, and muscle biopsies of children with suspected CMD help predict subtype-specific diagnoses.
• Genetic testing of these genes may help confirm a clinical diagnosis, predict disease prognosis and progression, facilitate early detection of symptoms, inform family planning and genetic counseling, or promote enrollment in clinical trials.

References:

• [3] Jul 3, 2019 — The most important diagnostic tools are CK level, nerve conduction study, and EMG with or without repetitive nerve stimulation, brain MRI, muscle biopsy.
• [6] by CG Bönnemann · 2014 · Cited by 362 — Note: The most important tools in the clinical differential diagnosis are: EMG/NCV to diagnose neurogenic involvement, muscle biopsy, and selective biochemical ...
• [13] Genetic testing of these genes may help confirm a clinical diagnosis, predict disease prognosis and progression, facilitate early detection of symptoms, inform family planning and genetic counseling, or promote enrollment in clinical trials.
• [14] The geographic and ethnic backgrounds, clinical features, brain imaging studies, muscle imaging studies, and muscle biopsies of children with suspected CMD help predict subtype-specific diagnoses.

Muscular dystrophy-dystroglycanopathy type B, also known as muscle-eye-brain disease (MEB), is a rare and severe form of muscular dystrophy that affects the muscles, eyes, and brain. While there is no specific treatment for this condition, researchers have been exploring various pharmacotherapeutic approaches to manage its symptoms.

One potential therapeutic approach being investigated is the use of BBP-418 (Ribitol). According to search results [1], BBP-418 has shown considerable success in improving dystroglycanopathy by reducing muscle fibrosis and infiltration. However, it's essential to note that this treatment is still in the experimental stages, and more research is needed to confirm its efficacy.

Another study suggests that partial restoration of glycosylation may be sufficient to prevent muscular dystrophy in a model mouse [4]. This finding has implications for the development of novel therapeutic strategies for muscular dystrophies, including MEB.

It's also worth noting that aggressive supportive care is essential to preserve muscle activity and manage symptoms in patients with congenital muscular dystrophies, including MEB [9].

In terms of specific treatments, there are no FDA-approved medications specifically designed for muscular dystrophy-dystroglycanopathy type B. However, researchers are exploring various pharmacotherapeutic approaches, including the use of exon-skipping drugs like eteplirsen, which has been approved for treating Duchenne muscular dystrophy [11].

Key points:

• BBP-418 (Ribitol) may be a potential therapeutic approach for improving dystroglycanopathy.
• Partial restoration of glycosylation may prevent muscular dystrophy in model mice.
• Aggressive supportive care is essential to manage symptoms and preserve muscle activity in patients with congenital muscular dystrophies, including MEB.
• No FDA-approved medications are specifically designed for muscular dystrophy-dystroglycanopathy type B.

References:

[1] Search result 1 [4] Search result 4 [9] Search result 9 [11] Search result 11

Muscular dystrophy-dystroglycanopathy type B, also known as Fukuyama-type congenital muscular dystrophy (FCMD), is a rare genetic disorder that affects muscle strength and intellectual development. When considering the differential diagnosis for this condition, several other disorders should be taken into account.

• Duchenne Muscular Dystrophy (DMD): This is one of the most common muscular dystrophies, characterized by progressive muscle degeneration and weakness [6]. While it shares some similarities with FMD, such as muscle weakness and wasting, DMD typically presents later in childhood than FMD.
• Becker Muscular Dystrophy (BMD): Another form of muscular dystrophy that can mimic the symptoms of FMD, BMD is caused by mutations in the same gene as DMD but results in a milder phenotype [6].
• Congenital Muscular Dystrophies (CMDs): These are a group of genetic muscle diseases that occur at birth or early during infancy. CMDs can present with muscle weakness, hypotonia, and other systemic features, making them a differential diagnosis for FMD [9][10].

The key to differentiating these conditions lies in their clinical presentation, laboratory findings, and imaging studies.

• Clinical Presentation: FMD typically presents with congenital onset of muscle weakness, intellectual disability, and mild structural brain abnormalities. In contrast, DMD and BMD often present later in childhood with progressive muscle degeneration [1].
• Laboratory Findings: Genetic testing can help identify the underlying cause of the condition. For example, mutations in the DYS gene are associated with FMD, while mutations in the DMD gene are responsible for DMD and BMD [4][5].
• Imaging Studies: MRI findings can also aid in differential diagnosis. In FMD, CNS involvement and specific MRI findings are key in distinguishing it from other CMDs [8].

In conclusion, when considering the differential diagnosis of muscular dystrophy-dystroglycanopathy type B, a comprehensive evaluation of clinical presentation, laboratory findings, and imaging studies is essential to accurately diagnose this rare genetic disorder.

References:

[1] Context 1 [4] Context 2 [5] Context 3 [6] Context 6 [8] Context 8