Lipoprotein Receptor-Related Protein 4 Antibody Positivity in the Youngest Patient in the Caucasus Region: A Case Report.

Juvenile myasthenia gravis is a rare disorder where antibodies targeting the acetylcholine receptor or, less frequently, muscle-specific kinase can be detected in the serum while about half of the patients can be seronegative. A pediatric patient with ocular myasthenia is presented whose serum was negative for acetylcholine receptor and muscle-specific kinase antibodies but tested positive for low-density lipoprotein receptor-related protein 4 antibodies. A favourable clinical response was observed to medical treatment with pyridostigmine and prednisolone, as expected in isolated ocular juvenile myasthenia gravis. This case exemplifies the very rare association of juvenile myasthenia gravis with low-density lipoprotein receptor-related protein 4 positivity, reported in only a few cases so far. The specificity of the antibody and the efficiency of medical treatment emphasize the importance of clinical suspicion and appropriate serological testing in juvenile myasthenia gravis in the absence of acetylcholine receptor and muscle-specific kinase antibodies.