There are at least three artists with this name.

Syndrome (1) is a Gothic and Visual Rock band from Japan founded by guitarist Ruiza (ex LAYBIAL) and bassist Kisaki (ex ＭＩＲＡＧＥ) in January 2000. The lineup was completed by drummer Shion, vocalist Tatsuya and guitarist Ken. The latter two left the band in June 2001 and were replaced by ASAGI (ex JE*REVIENS) and Sin (ex Vasalla). In its two-year long history the band has been very productive, releasing three mini albums, several singles and few video tapes. Some members even worked on solo releases and side projects.
Sadly, Syndrome had to disband in November 2002 due to Kisaki's health problems and the consequent closure of Matina. Asagi, Sin and Ruiza eventually formed D, while Shion joined Shelly Trip Realize.

Syndrome (2) is a Latvian experimental noise and dark ambient project founded in 1997 by members of Antireality, ray of the radiation, Biovaseline and Twrch Trwyth. It is dedicated to unrehearsed live recordings and performances exclusively and has to this day released 3 cassettes and 2 cdrs. Lately the obscure poet de7s whose spoken word was heard on a number of Syndrome recordings has joined the timeless project as a permanent member.

Syndrome (3) is an experimental project from Ghent, Belgium. Mathieu van de Kerckhove (guitarist of Amenra) and Tine Guns are syndrome. Their music mostly consist of post-rock and ambient elements.