PDZRN4 and multiple sclerosis: PDZ domain-containing ring finger 4 (PDZRN4) is located on chromosome 12q12 and encodes the PDZ domain-containing ring finger 4 (PDZRN4), which belongs to the LNX family and acts as a suppressor in multiple cancers (32, 33) and in association with multiple sclerosis in a GWAS (34).