Wilson's disease is caused by a deficiency in the ATP7B protein, not a deficiency of a nutrient or mineral in the body.
Explanation of ATP7B Deficiency and Wilson's Disease
Wilson's disease is a rare inherited disorder characterized by the body's inability to properly excrete copper. This leads to an accumulation of copper, primarily in the liver, brain, and corneas of the eyes. This accumulation is directly caused by a deficiency in the function of the ATP7B protein.
The Role of ATP7B
The ATP7B protein is primarily found in the liver and plays two crucial roles in copper metabolism:
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Attaching copper to ceruloplasmin: Ceruloplasmin is a protein that carries copper in the bloodstream. ATP7B attaches copper to ceruloplasmin, allowing it to be transported throughout the body.
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Excreting excess copper into bile: ATP7B transports excess copper into bile, which is then eliminated from the body through the digestive system.
Consequences of ATP7B Deficiency
When the ATP7B protein is deficient or non-functional (due to genetic mutations), the body cannot effectively perform these two functions. As a result:
- Copper is not properly attached to ceruloplasmin, leading to reduced levels of functional ceruloplasmin in the blood.
- Copper is not efficiently excreted into bile, leading to a buildup of copper in the liver.
Over time, the accumulated copper damages the liver and eventually spills over into other organs, including the brain and corneas. This leads to the characteristic symptoms of Wilson's disease.
Important Note: Copper Deficiency as a Consequence of Treatment
While Wilson's disease is caused by a deficiency in ATP7B function, leading to copper accumulation, treatment for Wilson's disease sometimes involves medications (decoppering agents) that can induce copper deficiency if overused. This iatrogenic copper deficiency can cause hematological and neurological symptoms. This is different from the primary cause of the disease.
In summary, Wilson's disease results from a deficiency in the function of the ATP7B protein, resulting in excess copper accumulation. It's not caused by a lack of dietary copper initially.
