In a recent report in the AJNR, 1 Koyama and Yagashita describe brain perfusion studies on single-photon emission CT in a 6-year-old boy diagnosed with pantothenate kinase–associated neurodegeneration (PKAN). Although the authors state that this patient was diagnosed on the basis of clinical findings, including the eye-of-the-tiger sign on T2-weighted MR imaging, there is no mention of diagnostic molecular testing of the causative gene, PANK2. The T2 image demonstrating the eye-of-the-tiger sign was not provided. A verbal description of the T2 findings without an accompanying image makes it difficult to know whether this patient has PKAN or another form of neurodegeneration with brain iron accumulation. Because the authors are reporting a new finding, it is critical for the reader to be certain of which disorder the patient has. On the basis of our extensive experience with PKAN, we recommend using molecular testing to confirm the diagnosis even in the presence of an eye-of-the-tiger sign. The current standard of care for a suspected diagnosis of PKAN is to obtain PANK2 mutation analysis. Although MR imaging can be strongly suggestive of PKAN, the diagnosis is not established without mutation studies.
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