Novel PANK2 mutation in a Chinese boy with PANK2-associated neurodegeneration A case report and review of Chinese cases

Rationale: Pantothenate kinase-associated neurodegeneration (PKAN), also called Hallervorden-Spatz Syndrome (HSS), is a rare neurodegeneration with brain iron accumulation from pantothenate kinase 2 gene (PANK2) mutation characterized as extrapyramidal symptoms. However, few studies involving PKAN patients were reported in China. This study was conducted to identify the genetic mutations in a Chinese boy with PKAN, and to review all PANK2 mutations reported in Chinese cases with PKAN. Patient concern: We reported a 23-year-old Chinese boy with PKAN, exhibiting difficulty in writing and manipulation using right hand with slow progression for 12 years. He spoke with a severe stutter when he was 15 years old. Diagnosis: Considering results of magnetic resonance images, brain computed tomography and medical history, the case was suspected to be related to genetic factors. Interventions: Whole exome sequencing was arranged, and the mutations were identified in his parents' genome. Outcomes: In the present study, whole exome sequencing revealed 2 novel mutations (c.1696C > G in exon 7 and c.1160_c. 1161insG in exon3) of the PANK2 gene in the proband. c.1696C > G and c.1160_c.1161insG, respectively, were confirmed in his father and mother. We also reviewed 14 different PANK2 mutations, most of which were missense type in Chinese cases. Those mutations did not show apparent hotspots,but exon 3 and 4 were frequently involved. Lessons: Two novel compound heterozygous mutations were identified and considered to be pathogenic in PKAN patients. This review of the reports indicated that atypical PKAN is the more common phenotype in China and no apparent genotype-phenotype correlation was found.