Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a condition that affects how the body uses an important vitamin called thiamine (vitamin B1).
Thiamine is essential for the nervous system to work correctly. When thiamine levels drop, often due to fever, illness, or stress, it can cause problems with movement. Symptoms can include muscle stiffness, weakness, or trouble with balance and coordination. Muscles in the face can also be affected, leading to difficulties with chewing, swallowing, speaking, or moving the eyes. BTBGD comes in three forms: classic BTBGD (early childhood encephalopathy), early infantile Leigh-like syndrome, and adult-onset Wernicke-like encephalopathy.
Classic BTBGD: This is the most common form. Symptoms usually start between ages 3 and 10 and include seizures, abnormal muscle movements, weakness, and confusion. These symptoms often occur in episodes triggered by illness or stress. Without treatment, these episodes can be severe and may lead to coma or death.
Early Infantile Leigh-like Syndrome: This is the most severe form and begins in the first three months of life. The symptoms are similar to the classic form but can cause more damage to the brain. Babies may have trouble feeding, vomit frequently, and have worsening seizures over time.
Adult-Onset Wernicke-like Encephalopathy: This is the rarest and mildest form of BTBGD. Symptoms usually appear in the teens or twenties and include seizures, abnormal eye movements, and difficulty walking.
BTBGD is treated using supplements of high-dose thiamine (vitamin B1) and/or biotin (vitamin B7). Some individuals with muscle weakness or difficulty with moving or speaking may benefit from physical, occupational, and speech therapies.
This group of conditions is caused by pathogenic (disease-causing) variants in the SLC19A3 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance of having a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
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Written August 2024
