muscular dystrophy-dystroglycanopathy type B6

Muscular dystrophy-dystroglycanopathy type B6, also known as MDDGB6, is a rare and severe form of congenital muscular dystrophy.

Characteristics:

• Autosomal recessive inheritance: This condition is inherited in an autosomal recessive pattern, meaning that a person must inherit two copies of the mutated gene (one from each parent) to develop the condition.
• Muscular dystrophy with impaired intellectual development: MDDGB6 is characterized by progressive muscle weakness and wasting, as well as significant impairments in cognitive function and intellectual development.
• Structural brain abnormalities: Individuals with MDDGB6 often have structural brain abnormalities, which can affect various aspects of their development and functioning.

Symptoms:

• Muscle weakness and wasting: Affected individuals may experience progressive muscle weakness and

Muscular dystrophy-dystroglycanopathy type B6, also known as MDDGB6, is a rare congenital disorder characterized by impaired intellectual development and structural brain abnormalities. The condition is part of a group of disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239).

Clinical Signs and Symptoms:

• Profound intellectual disability [8]
• White matter changes in the brain
• Reduced immunolabeling of alpha-dystroglycan in skeletal muscle

Additionally, some individuals with MDDGB6 may experience other symptoms such as:

• Abnormality of head or neck (e.g., macroglossia)
• Elevated circulating creatine kinase concentration
• Abnormality of the eye [2]

It's essential to note that these symptoms can vary in severity and presentation among affected individuals.

References:

[8] - This condition is characterized by profound intellectual disability, white matter changes, and reduced immunolabeling of alpha-dystroglycan in skeletal muscle ... [2] - Abnormality of head or neck. Macroglossia · Abnormality of metabolism/homeostasis. Elevated circulating creatine kinase concentration · Abnormality of the eye.

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Muscular dystrophy-dystroglycanopathy type B6 (MDDGB6) is a congenital muscular dystrophy characterized by autosomal recessive inheritance, impaired intellectual development, and structural brain abnormalities [5]. Diagnosing MDDGB6 can be challenging due to its rarity and the complexity of the disease.

Genetic Testing Genetic testing is a crucial diagnostic tool for MDDGB6. The Invitae Congenital Muscular Dystrophy Panel analyzes genes associated with congenital muscular dystrophies, including those responsible for MDDGB6 [4]. This panel can detect causative mutations in approximately 30-66% of children with dystroglycanopathy [14].

Clinical Genetic Tests Several clinical genetic tests are available to diagnose MDDGB6. For example, CeGaT GmbH offers a test for conditions, including muscular dystrophy-dystroglycanopathy type B6 [3]. Intergen also provides a clinical genetic test for MDDGB6, focusing on the LARGE1 gene (22q12.3) [6].

Blood Samples and Other Tests While not specific to MDDGB6, blood samples can be examined for mutations in some genes that cause types of muscular dystrophy, especially in people diagnosed with myotonic muscular dystrophy [10]. Lung-monitoring tests are also used to check lung function, which may be affected in individuals with muscular dystrophies [10].

Important Considerations It's essential to note that a diagnosis of MDDGB6 can be extremely challenging. A healthcare provider may use various diagnostic tests and consider other conditions to rule out before confirming the diagnosis.

References: [3] - Clinical Genetic Test offered by CeGaT GmbH for conditions (37): Muscular dystrophy ... Muscular dystrophy-dystroglycanopathy type B6 · Myosin storage myopathy. [4] - The Invitae Congenital Muscular Dystrophy Panel analyzes genes associated with congenital muscular dystrophies, a heterogeneous group of neuromuscular ... [5] - MDDGB6 is an autosomal recessive congenital muscular dystrophy with impaired intellectual development and structural brain abnormalities (Longman et al., ... [6] - Clinical Genetic Test offered by Intergen for conditions (1): Muscular dystrophy-dystroglycanopathy type B6. [10] - Blood samples can be examined for mutations in some genes that cause types of muscular dystrophy, especially in people diagnosed with myotonic muscular dystrophy. [14] - 22,26,e24−e28 studies demonstrated that genetic testing can detect causative mutations in 30% to 66% of children with dystroglycanopathy.

Treatment Options for Muscular Dystrophy-Dystroglycanopathy Type B6

Muscular dystrophy-dystroglycanopathy type B6, also known as MDDGB6, is a rare and severe form of muscular dystrophy. While there are no specific treatments that can cure the condition, various drug therapies have been explored to manage its symptoms.

Prednisone and Deflazacort

According to recent studies [2], treatment for MDDGB6 often involves the use of corticosteroids such as prednisone (0.75 mg/kg/day) or deflazacort (0.9 mg/kg/day). These medications have been shown to improve muscle strength and overall quality of life in patients with muscular dystrophy.

Prodrug Treatments

Research has also investigated the potential benefits of prodrug treatments, such as those demonstrated by a study on isoprenoid synthase domain defects [3]. While more research is needed, these findings suggest that prodrug therapies may offer new avenues for treating MDDGB6 and other forms of muscular dystrophy.

Eteplirsen

Another treatment option being explored is eteplirsen, an exon 51-skipping drug approved by the FDA to treat Duchenne muscular dystrophy patients with exon 51 skippable mutations [4]. While its effectiveness for MDDGB6 specifically has not been extensively studied, it may offer a potential therapeutic approach for this condition.

Other Therapeutic Approaches

In addition to these specific treatments, various other therapies have been investigated as potential options for managing the symptoms of muscular dystrophy-dystroglycanopathy type B6. These include counseling and support services to help patients cope with the emotional and psychological aspects of their condition [8].

References:

[1] A Luna-Angulo (2024) - Secondary Dystroglycanopathies, FKRP, Rapamycin (2 mg/kg once a day/4 weeks)

[2] A Luna-Angulo (2024) - This treatment is generally based on the use of prednisone (0.75 mg/kg/day) or deflazacort (0.9 mg/kg/day).

[3] H Tokuoka (2022) - In this study, we demonstrate that prodrug treatments can ameliorate muscular dystrophy caused by defects in isoprenoid synthase domain.

[4] ML Chu (2018) - Eteplirsen is an exon 51-skipping drug approved by the FDA to treat Duchenne muscular dystrophy patients with exon 51 skippable mutations.

Muscular dystrophy-dystroglycanopathy type B6 (MDDGB6) is a rare and severe form of congenital muscular dystrophy characterized by profound intellectual disability, white matter changes, and reduced immunolabeling of alpha-dystroglycan in skeletal muscle [3]. The differential diagnosis for MDDGB6 involves ruling out other conditions that may present with similar symptoms.

According to the search results, the differential diagnosis for muscular dystrophy is broad when a previously healthy child presents with generalized weakness of rapid onset and an elevated CK (>1,000 IU/L) [14]. In such cases, the most common diagnosis is viral myositis or other neuromuscular disorders. However, in some cases, muscular dystrophy may be suspected based on clinical phenotype, inheritance pattern, and associated manifestations.

The presence of distinguishing clinical and muscle biopsy features can efficiently narrow the differential diagnosis to a few conditions, including LGMD2I or MFM, which are associated with oropharyngeal or ventilatory muscle weakness [13]. Other forms of muscular dystrophy, such as LGMD2B and LGMD2D, may also be considered in the differential diagnosis.

In addition, elevated serum CK at birth or early in life and/or muscle biopsy consistent with a dystrophic process can aid in the differential diagnosis of MDDGB6 [5].

It's worth noting that the Invitae Congenital Muscular Dystrophy Panel analyzes genes associated with congenital muscular dystrophies, which may help in diagnosing MDDGB6 by identifying mutations in the LARGE gene [8].