Isaksson, Johan ORCID: https://orcid.org/0000-0001-9458-9167, Tammimies, Kristiina ORCID: https://orcid.org/0000-0002-6664-7451, Neufeld, Janina ORCID: https://orcid.org/0000-0001-9800-2052, Cauvet, Elodie ORCID: https://orcid.org/0000-0003-1993-6549, Lundin, Karl ORCID: https://orcid.org/0000-0001-9901-1110, Buitelaar, Jan K. ORCID: https://orcid.org/0000-0001-5313-5476, Loth, Eva ORCID: https://orcid.org/0000-0001-5552-2146, Murphy, Declan G. M. ORCID: https://orcid.org/0000-0002-5078-9025, Spooren, Will ORCID: https://orcid.org/0000-0002-5450-0823, Bolte, Sven ORCID: https://orcid.org/0000-0001-9574-9855, Ahmad, Jumana ORCID: https://orcid.org/0000-0001-5271-0731 and and the EU-AIMS group, (50+ additional authors) (2018) EU-AIMS Longitudinal European Autism Project (LEAP) the autism twin cohort. Molecular Autism, 9:26. ISSN 2040-2392 (Online) (doi:10.1186/s13229-018-0212-x)