title: Reply.
authors.affiliation: University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Carol Ann
authors.initials: CA
authors.lastname: Hitchon
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Hester
authors.initials: H
authors.lastname: Koppejan
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Leendert A
authors.initials: LA
authors.lastname: Trouw
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Tom J W
authors.initials: TJ
authors.lastname: Huizinga
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: René E M
authors.initials: RE
authors.lastname: Toes
authors.affiliation: University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Hani S
authors.initials: HS
authors.lastname: El-Gabalawy