Exome and regulatory element sequencing of neuromyelitis optica patients

• Homogeneous genetic etiology of NMO was not found in the Finnish population.
• We studied a population with a prominent founder effect of disease alleles.
• Further studies are needed to verify the role of the found shared rare variants.
• One of the shared variants, PDZD2, contains a PDZ domain that interacts with AQP4.
• We provide a list of all rare missense variants for future studies.

Neuromyelitis optica (NMO) is rare in Finland. To identify rare genetic variants contributing to NMO risk we performed whole exome, HLA and regulatory region sequencing in all ascertained cases during 2005–2013 (n = 5) in a Southern Finnish population of 1.6 million. There were no rare variant shared by all patients. Four missense variants were shared by two patients in C3ORF20, PDZD2, C5ORF47 and ZNF606. Another PDZD2 variant was found in a third patient. In the non-coding sequence two predictably functional rare variants were shared by two patients. Our results do not support a homogeneous genetic etiology of NMO in Finland.