Hostettler, Isabel C MD; Pavlou, Menelaos PhD; Ambler, Gareth Alg, Varinder S Bonner, Stephen FFICM; Walsh, Daniel FRCS; Bulters, Diederik Kitchen, Neil Brown, Martin M FRCP; Grieve, Joan Houlden, Henry Werring, David J PhD, FRCP, on behalf of the Genetics and Observational Subarachnoid Haemorrhage (GOSH) Study investigators