What is the fine-grained topic of the following text: Matesanz F, González-Pérez A, Lucas M, Sanna S, Gayán J, Urcelay E, Zara I, Pitzalis M, Cavanillas ML, Arroyo R, Zoledziewska M, Marrosu M, Fernández O, Leyva L, Alcina A, Fedetz M, Moreno-Rey C, Velasco J, Real LM, Ruiz-Peña JL, Cucca F, Ruiz A, Izquierdo G. Genome-wide association study of multiple sclerosis confirms a novel locus at 5p13.1. Only return the topic.
The topic of the text is a genome-wide association study of multiple sclerosis confirming a novel locus at 5p13.1.