Thiamine metabolism dysfunction syndrome 5 (episodic encephalopathy type)
Type of disease: Rare conditions
Encephalopathy due to thiamine pyrophosphokinase deficiency is a rare genetic disorder that involves a problem with the breakdown of thiamine, or vitamin B1. Vitamin B1 is important in breaking down fats and proteins, and plays a key role in making sure the brain works correctly. In episodic encephalopathy due to thiamine pyrophosphokinase deficiency, individuals have some loss of memory and brain function, slight personality changes, a hard time concentrating, and low energy levels. Individuals usually develop loss of coordination, repetitive muscle contractions, and muscle stiffness, which may eventually lead to no longer being able to walk. In some, but not all individuals, mental development is normal. Symptoms usually begin at a young age during infancy or childhood.
This condition is caused by a change (mutation) in the TPK1 gene and is passed through families in an autosomal recessive manner. Autosomal recessive means that an individual must have two mutations in order to have this condition. A person with only one mutation is called a carrier because they “carry” a mutation but do not have the condition. If both parents are carriers of a mutation, their children have a one in four chance (25%) of having the condition.
Diagnosis is made by physical exam and determining the amount of a chemical called lactate in the blood and spinal fluid. In some cases, treatment with oral vitamin B1 supplements has helped to relieve symptoms. If you or a family member has been diagnosed with episodic encephalopathy due to thiamine pyrophosphokinase deficiency, talk with your doctor about the most current treatment options. Support groups are also good resources of support and information.