We usually encounter the terms “upstream” and “downstream” when researchers talk about cell processes. What do they mean by that?
Well, we are familiar with the flow of information in cells or what is usually referred to as the “central dogma” of molecular biology, right? That is, – DNA ---> RNA ---> proteins. Well, upstream means the replication of DNA and the formation of RNA or transcription, while downstream is the formation of proteins or translation. So when the write-up says that the problem appears to be upstream, then it means that something is wrong with either the replication or the transcription process. A downstream problem on the other hand means something wrong with the translation process.