Histidinemia

Histidinemia is a rare inherited metabolic disorder that affects the breakdown of the amino acid histidine. It is caused by a deficiency in the enzyme histidase, which is responsible for converting histidine to urocanic acid. This deficiency leads to an accumulation of histidine in the blood and urine, a condition known as histidinemia.

The disorder is typically diagnosed through newborn screening or biochemical testing of amino acids. Symptoms can vary widely, with some individuals being asymptomatic and others experiencing mild to moderate intellectual disability, speech impediments, and eczema. However, many people with histidinemia do not show any noticeable symptoms.

Histidinemia is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition. Carriers of the gene will have one normal copy and one mutated copy and typically do not exhibit symptoms.

There is no cure for histidinemia, but management often involves a histidine-restricted diet. This dietary approach aims to reduce histidine intake to prevent excessive buildup in the body. Regular monitoring of histidine levels in the blood and urine is important to assess the effectiveness of the diet and manage the condition. Research into the long-term effects and optimal treatment strategies for histidinemia is ongoing.