Abrahams coached Harlequins academy between 2011 and 2019 and went on to work on the sevens management teams with USA women and England men.
He was appointed head coach of Wales women in November 2020 but left the following summer after less than nine months in the role.
A Welsh Rugby Union statement said: “Our sincerest condolences to the family and friends of Warren Abrahams from everyone in Welsh rugby.”
Abrahams went on to work as a consultant with Brazil’s national women’s sevens team before joining Belgium earlier this year.
Harlequins said: “His passion, leadership and commitment to developing players were felt not only at Harlequins, but throughout the wider rugby world during his distinguished career.”