Will just taking out the "it" make this sentence correct?
The disease is typified by a delay in motor development, by self-destructive behavior, and it leads to death.
No, in order to make the series' elements parallel, you need a third phrase that starts with "by" and ends with a prepositional phrase ... so you have this:
... by a delay ..., by self-destructive behavior, and by ________________.
How will you rephrase the last part of this sentence?
and by death.
Yes, that works. Good!
To determine whether removing the word "it" would make the sentence correct, we need to carefully analyze the sentence structure and meaning.
The original sentence is: "The disease is typified by a delay in motor development, by self-destructive behavior, and it leads to death."
By removing the word "it," the revised sentence would be: "The disease is typified by a delay in motor development, by self-destructive behavior, and leads to death."
Both versions of the sentence are grammatically correct, but they have a slight difference in meaning.
In the original sentence, the pronoun "it" is used to refer back to the noun "disease." This adds clarity by explicitly stating that the disease is what leads to death. Without "it," the sentence still makes sense, but it becomes slightly more ambiguous. It may not be immediately clear what leads to death, as the direct connection to the disease is not explicitly mentioned.
If you want to make the revised sentence clearer, you can consider rephrasing it as follows:
"The disease is typified by a delay in motor development, by self-destructive behavior, and ultimately leads to death."
In this revised version, the word "ultimately" helps establish a clearer connection between the disease and death. However, whether to include "it" or use alternative phrasing ultimately depends on the specific context and desired emphasis.