title: Commentary: sex difference differences? A reply to Constantino.
abstract: Messinger et al. found a 3.18 odds ratio of male to female ASD recurrence in 1241 prospectively followed high-risk (HR) siblings. Among high-risk siblings (with and without ASD), as well as among 583 low-risk controls, girls exhibited higher performance on the Mullen Scales of Early Learning, as well as lower restricted and repetitive behavior severity scores on the Autism Diagnostic Observation Schedule (ADOS) than boys. That is, female-favoring sex differences in developmental performance and autism traits were evident among low-risk and non-ASD high-risk children, as well as those with ASD. Constantino (Mol Autism) suggests that sex differences in categorical ASD outcomes in Messinger et al. should be understood as a female protective effect. We are receptive to Constantino's (Mol Autism) suggestion, and propose that quantitative sex differences in autism-related features are keys to understanding this female protective effect.
authors.affiliation: University of Miami, Coral Gables, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Messinger
authors.affiliation: University of California, Davis, Davis, USA.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Young
authors.affiliation: Seattle Children's Research Institute, Seattle, USA ; University of Washington, Seattle, USA.
authors.forename: Sara Jane
authors.identifier: 0000-0003-4101-6255
authors.initials: SJ
authors.lastname: Webb
authors.affiliation: University of California, Davis, Davis, USA.
authors.forename: Sally
authors.initials: S
authors.lastname: Ozonoff
authors.affiliation: Izaak Walton Killam Health Centre, Halifax, Canada ; Dalhousie University, Halifax, Canada.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Bryson
authors.affiliation: University of Massachusetts, Boston, Boston, USA.
authors.forename: Alice
authors.initials: A
authors.lastname: Carter
authors.affiliation: University of California, San Diego, La Jolla, USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Carver
authors.affiliation: King's College London, London, UK.
authors.forename: Tony
authors.initials: T
authors.lastname: Charman
authors.affiliation: Yale University School of Medicine, New Haven, USA.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Chawarska
authors.affiliation: University of Calgary, Calgary, Canada.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Curtin
authors.affiliation: University of California, San Diego, La Jolla, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Dobkins
authors.affiliation: University of California, Davis, Davis, USA.
authors.forename: Irva
authors.initials: I
authors.lastname: Hertz-Picciotto
authors.affiliation: University of California, Los Angeles, Los Angeles, USA.
authors.forename: Ted
authors.initials: T
authors.lastname: Hutman
authors.affiliation: University of Pittsburgh, Pittsburgh, USA.
authors.forename: Jana M
authors.initials: JM
authors.lastname: Iverson
authors.affiliation: Kennedy Krieger Institute, Baltimore, USA ; John Hopkins School of Medicine, Baltimore, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Landa
authors.affiliation: Harvard Medical School, Boston, USA ; Harvard Graduate School of Education, Cambridge, USA ; Boston Children's Hospital, Boston, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Nelson
authors.affiliation: University of Washington, Seattle, USA.
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Stone
authors.affiliation: Boston University, Boston, USA.
authors.forename: Helen
authors.initials: H
authors.lastname: Tager-Flusberg
authors.affiliation: University of Alberta, Edmonton, Canada.
authors.forename: Lonnie
authors.initials: L
authors.lastname: Zwaigenbaum
keywords: Autism spectrum disorder; Female protective effect; High-risk siblings; Sex differences