Final answer:
The disorder that was incorrectly linked to the MMR vaccine without appropriate scientific research is autism. Extensive scientific studies have consistently shown that there is no causal relationship between the MMR vaccine and autism.
Step-by-step explanation:
The disorder that was incorrectly linked to the MMR vaccine without appropriate scientific research is autism. Despite claims made by some individuals, extensive scientific studies have consistently shown that there is no causal relationship between the MMR vaccine and autism. The initial research that suggested a link between these two was later discredited and retracted, and subsequent studies have found no evidence to support this claim.