SNP Shot: Genomic Insights

Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a neurological condition that impacts the brain, specifically the basal ganglia, which are crucial for controlling movement. As the name implies, symptoms can improve with biotin and thiamine supplementation. However, without consistent, early vitamin treatment, individuals with BTBGD will experience progressively worsening neurological issues. The specific neurological problems and their severity vary considerably, even among affected family members.

Symptoms of BTBGD usually manifest between ages 3 and 10, though onset can occur at any age. Many symptoms involve movement difficulties, such as involuntary muscle contractions (dystonia), muscle stiffness (rigidity), weakness on one or both sides of the body (hemiparesis or quadriparesis), coordination problems (ataxia), and overactive reflexes (hyperreflexia). Facial movements can also be affected, potentially leading to facial paralysis (supranuclear facial palsy), eye muscle paralysis (external ophthalmoplegia), difficulty chewing or swallowing (dysphagia), and speech impairments. Additionally, affected individuals may experience confusion, loss of learned abilities, intellectual disability, and seizures. In severe cases, the condition can lead to coma and be life-threatening.

The neurological symptoms often appear as increasingly severe episodes, often triggered by fever, injury, or other bodily stressors. Less frequently, symptoms are constant or slowly worsen over time, rather than occurring in distinct episodes. In these cases, the neurological problems are generally limited to dystonia, seizures, and delays in mental and motor development (psychomotor delay).

Inheritance:

BTBGD follows an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. The parents, who each carry one copy of the mutated gene, usually do not exhibit any symptoms of the disease.