Background: Rett syndrome (RTT) is a neurodevelopmental disorder primarily caused by mutations in the methyl-CpG-binding protein 2 (MECP2) gene, resulting in developmental regression after normal development during infancy. Transient presentation of many autistic features is also commonly seen in RTT. Anti-myelin oligodendrocyte glycoprotein (MOG)-antibody encephalitis is an acquired relapsing demyelinating syndrome characterized by a variety of neuroinflammatory symptoms. Here, we report a case of anti-MOG antibody encephalitis in a patient with genetically confirmed RTT, which mimicked many of the features of RTT.
Case report: A three-year-old girl presented with subacute verbal and motor dysfunction, along with involuntary movements and marked irritability. Magnetic resonance imaging (MRI) revealed extensive white matter lesions, with anti-MOG antibodies detected in the serum and cerebrospinal fluid, resulting in an initial diagnosis of anti-MOG antibody encephalitis. However, additional testing of the MECP2 gene was performed in response to persistent involuntary hand movements in combination with progressive verbal and motor deterioration. Sequencing analysis revealed a known pathogenic mutation in MEPC2, indicating a concurrent diagnosis of RTT.
Conclusion: Both RTT and anti-MOG antibody encephalitis are rare conditions. Similarities in disease presentation suggest that anti-MOG antibody encephalitis may mimic many of the symptoms of RTT.
Keywords: Anti-MOG antibody encephalitis; MECP2; MRI; Mutation; Rett syndrome.
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