This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which of the following is not true regarding wilson's disease 
Select and explain. 
A. ATP7B mutation leading to impairment in copper metabolism, B. Most specific screening test is Urinary excretion of copper, C. Gold standard test is liver biopsy, D. KF ring is present in upto 30% cases
D: KF ring is present in upto 30% cases
Answer: D: KF ring is present in upto 30% cases 
Explanation: KF ring is present in upto 99 % of cases.
ATP 7B mutation results in defective biliary copper excretion into bile as copper can't be incorporated into apoceruloplasmin.
Thus copper accumulates in excess amounts in liver and brain.
The copper accumulation in descemets membrane of cornea is manifested as KF rings, in the eye.