What is the best treatment for rancid butter syndrome?

Tyrosinemia type 1?: By rancid butter syndrome i think you mean tyrosinemia type 1. This occurs when an enzyme, called fumarylacetoacetase (fah), is either missing or not working properly and therefore tyrosine accumulate. It is treated using special medical formulas in place of other things in the diet that contain tyrosine. A medication known as ntbc is also used in some chronic cases. See a metabolism specialist.