distal myopathy with anterior tibial onset

Distal Myopathy with Anterior Tibial Onset: A Rare Genetic Neuromuscular Disease

Distal myopathy with anterior tibial onset (DMAT) is a rare genetic neuromuscular disease characterized by progressive muscle weakness, starting in the anterior tibial muscles and later involving lower and upper limb muscles. This condition is associated with increased serum creatine kinase levels and absence of dysferlin on muscle biopsy.

Key Features:

• Progressive Muscle Weakness: The disease starts with weakness in the anterior tibial muscles, which gradually progresses to involve lower and upper limb muscles.
• Increased Serum Creatine Kinase Levels: Elevated levels of serum creatine kinase are a hallmark of this condition.
• Absence of Dysferlin on Muscle Biopsy: The absence of dysferlin protein on muscle biopsy is a diagnostic feature of DMAT.

Age of Onset and Disease Course

The onset of DMAT typically occurs between 14 and 28 years of age, with the anterior tibial muscles being the first to be affected. The disease course progresses rapidly, leading to the involvement of lower and upper limb muscles, and necessitating the use of a wheelchair within 11-22 years from onset.

Genetic Basis

DMAT is an autosomal recessive muscle disorder caused by homozygous mutations in the gene encoding dysferlin (DYSF) on chromosome 2p13. This genetic mutation leads to the absence of dysferlin protein, which is essential for muscle function and integrity.

References:

• [1] A rare genetic neuromuscular disease with characteristics of a progressive muscle weakness starting in the anterior tibial muscles, later involving lower and upper limb

Distal myopathy with anterior tibial onset, also known as distal myopathy with tibialis anterior muscle involvement, is a rare genetic neuromuscular disease characterized by progressive muscle weakness starting in the anterior tibial muscles.

Common signs and symptoms:

• Weakness and wasting (atrophy) of the anterior tibial muscle, which helps control up-and-down movements of the foot [1]
• Progressive muscle weakness that can spread to other muscles in the lower extremities, including the calf muscles [3]
• Muscle weakness may also affect the upper limbs, although this is less common [2]
• Clumsiness and difficulty with fine motor tasks, such as writing or using small objects [8]

Early symptoms:

• Weakness and wasting of the tibialis anterior muscle, which can lead to difficulties with walking and balance [4]
• Steppage gait, where the person has to lift their legs high to avoid tripping due to weakness in the lower extremities [8]

Progression of symptoms:

• Muscle weakness can progress to other muscles in the distal limbs, including the hands and feet [5]
• Claw hand contractures may develop as a result of muscle weakness in the hands [8]
• Glutei and other proximal muscles may also be affected over time [9]

It's essential to note that distal myopathy with anterior tibial onset is a rare condition, and not all individuals will experience all of these symptoms. If you suspect you or someone else has this condition, it's crucial to consult with a healthcare professional for proper diagnosis and treatment.

References: [1] - Context result 4 [2] - Context result 2 [3] - Context result 3 [4] - Context result 4 [5] - Context result 5 [8] - Context result 8

Diagnostic Tests for Distal Myopathy with Anterior Tibial Onset

Distal myopathy with anterior tibial onset is a rare, genetic neuromuscular disease characterized by progressive muscle weakness starting in the anterior tibial muscles. To diagnose this condition, several diagnostic tests are employed.

• Electromyography (EMG): This test assesses the health of muscles and the nerves that control them. EMG can help identify abnormal electrical activity in the muscles, which is a characteristic feature of distal myopathy with anterior tibial onset [4].
• Magnetic Resonance Imaging (MRI): MRI scans can provide detailed images of the muscles and surrounding tissues, helping to confirm the diagnosis and rule out other conditions [4].
• Specialized Blood Tests: Elevated levels of creatine kinase (CK) in the blood are a hallmark of distal myopathy with anterior tibial onset. Measuring CK levels can help support the diagnosis [5].
• Muscle Biopsy: A muscle biopsy of the distal muscles showing dystrophic features and prominent rimmed vacuoles is also used to confirm the diagnosis [6].

These diagnostic tests are essential in confirming the presence of distal myopathy with anterior tibial onset, allowing for proper management and treatment of this rare condition.

References: [4] - A thorough clinical evaluation, a detailed patient history, identification of characteristic findings, and various tests including EMG and MRI are used to diagnose distal myopathy. [1] [5] - An elevation of the level of the enzyme creatine kinase (also known as creatine phosphokinase (CK; EC 2.7.3.2) in the blood is a characteristic feature of distal myopathy with anterior tibial onset. [5] [6] - Diagnosis relies on molecular genetic testing, and additional examinations include muscle biopsy of distal muscles showing dystrophic features and prominent rimmed vacuoles. [6]

Current Drug Treatments for Distal Myopathy with Anterior Tibial Onset

Unfortunately, there are no FDA-approved drugs specifically designed to treat distal myopathy with anterior tibial onset (DMAT). However, researchers have been exploring various treatment options to manage the symptoms and slow disease progression.

• Vamorolone: A study published in 2023 [7] mentioned vamorolone as a potential therapeutic option for LGMD2B and MM patients. Although not specifically targeting DMAT, it may be worth considering its

Distal Myopathy with Anterior Tibial Onset: Differential Diagnosis

Distal myopathy with anterior tibial onset is a rare, genetic neuromuscular disease characterized by progressive muscle weakness starting in the anterior tibial muscles. The differential diagnosis of this condition involves several other myopathies that can present with similar symptoms.

Key Features to Consider:

• Muscle Weakness: The primary symptom of distal myopathy with anterior tibial onset is muscle weakness, particularly in the anterior compartment of the leg.
• Increased Serum Creatine Kinase Levels: Elevated serum creatine kinase levels are a common finding in this condition.
• Absence of Dysferlin on Muscle Biopsy: The absence of dysferlin on muscle biopsy is a key diagnostic feature.

Differential Diagnosis:

The differential diagnosis for distal myopathy with anterior tibial onset includes:

• Calpain-3 Mutation: A genetic mutation that can cause similar symptoms.
• Muscle Filaminopathy: A rare, genetic neuromuscular disease characterized by muscle weakness and wasting.
• Sporadic Inclusion Body Myositis (sIBM): An autoimmune disorder that can present with muscle weakness and atrophy.

Clinical Diagnosis

The clinical diagnosis of distal myopathy with anterior tibial onset is often possible with distinctive onset, CK levels, and association with particular ethnic groups. A thorough medical history, physical examination, and laboratory tests are essential for accurate diagnosis.

References:

• [13] Distal myopathy with anterior tibial onset is characterized by leg weakness that involves the muscles of the anterior compartment of the leg, causing foot drop [Illa et al 2001].
• [15] Distal myopathy with anterior tibial onset is a rare, genetic neuromuscular disease characterized by a progressive muscle weakness starting in the anterior tibial muscles, later involving lower and upper limb muscles, associated with an increased serum creatine kinase levels and absence of dysferlin on muscle biopsy.