Progressive multifocal leukoencephalopathy in a patient with novel mutation in the RAC2 gene: a case report.

BACKGROUND: Progressive multifocal leukoencephalopathy is a rare demyelinating disease that is often secondary to lytic destruction of oligodendrocytes and, to a lesser extent, to astrocytes' response to human neurotrophic John Cunningham polyomavirus. Any underlying congenital disorder of primary or secondary immunodeficiency may predispose to virus infection and possible invasion of the brain. We present the first reported case of progressive multifocal leukoencephalopathy due to a mutation in the RAC2 gene.

CASE PRESENTATION: We describe the case of a 34-year-old Iranian man with recurrent infections from the age of 2 years, along with other disorders such as nephritic syndrome, factor XI deficiency, and hypogammaglobulinemia. He was treated regularly with intravenous immunoglobulin from the age of 10 years with a diagnosis of common variable immune deficiency. Genetic testing confirmed a novel homozygous mutation in the RAC2 gene in the patient. Owing to the onset of neurological symptoms a few months ago, the patient was completely avaluated, which confirmed the diagnosis of PML. Despite all efforts, the patient died shortly after progression of neurological symptoms.

CONCLUSIONS: According to previous studies, progressive multifocal leukoencephalopathy has been associated with 26 cases of primary immunodeficiency. Our patient presents a new case of primary immunodeficiency with progressive multifocal leukoencephalopathy. Accurate examination of these cases can help us to gain insight into the immune response to John Cunningham virus and better treat this potentially deadly disease.