NounをAdjectiveとするNoun meaning something like a normal adjective

Question

This is a bit embarrassing, but on no less than the very first line of Komi-san, in Japanese, I'm presented with the following:

Now I've searched for a solid hour and found no definition for NounをAdjectiveとするNoun that makes sense in this context. Specifically:

人付き合いを苦手とする症状

DeepL gives something along the lines of "The symptoms of bad social disposition".

The English translation gives something like "it's a condition where a person has trouble communicating with other people"

I'm now unsure if the first big line is crucial here. I'm just kind of stumped as to how this grammar works.

Answer 1

「AをBとする」 can mean not only "to regard A as B", "to use A as B", but also "to have A as B", or even "(Speaking of the subject,) A is B."

マリアを母とし、... (≈マリアが母で...)
日本語を母語とし、... (≈日本語が母語で...)
先天性心疾患治療を得意とします。 (≈先天性心疾患治療が得意です。)

I think this usage sounds pretty literary. (These examples above sound more literary than the rephrased counterparts in the brackets.) 　

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And 「AをBとするXX」 can mean "XX having A as B", "XX with A being B", or "XX, where A is B" (≈「AがBであるXX」「AがBのXX」), as in...

• 「遺伝子組換えでない食品を原材料とする場合」 (≈遺伝子組換えでない食品が原材料である場合), "a case where 遺伝子組み換えでない食品 is (a product's) ingredient"
• 「日向灘を震源とする地震」 (≈日向灘が震源である地震), "an earthquake with 日向灘 being its 震源"
• 「中学生を対象とするコンクール」 (≈中学生が対象のコンクール), "a competition where 中学生 are its 対象"
• 「日本語を母語とする者」 (≈日本語が母語である者) "someone having Japanese as their native language" ⇒ "someone whose native language is Japanese"

Similar examples:

• 「治療を目的とする手術」 (≈治療が目的である手術)
• 「ストーブを原因とする火災」 (≈ストーブが原因の火災)
• 「外科を専門とする医師」 (≈外科が専門の医師)
• 「英語を不得意とする学生」 (≈英語が不得意な学生)

Similarly...

「人付き合いを苦手とする症状」≈「人付き合いが苦手である症状」

I think it can be understood as (literally) "a symptom where socialising is one's weakness", ⇒ "A symptom where one is bad at socialising".