BPAN: The only X-linked dominant NBIA disorder.

Beta-propeller protein-associated neurodegeneration (BPAN) is the most recently identified subtype of neurodegeneration with brain iron accumulation (NBIA), being unique with respect to the underlying disease genetics, the associated clinical presentation, and the suggested pathomechanism. Mutations in X-chromosomal WDR45 arise de novo; however, the dominant pattern of inheritance is unusual for an X-linked disorder and additional mechanisms such as X-inactivation or somatic mosaicism are likely to contribute to the phenotype that is indistinguishable between males and females. The course of the disease is two-staged with developmental delay and intellectual disability in childhood and a second phase of rapid neurological deterioration characterized by parkinsonism and dementia occurring in adolescence or early adulthood. At this time, neuroimaging findings are characteristic and provide excellent diagnostic guidance. There is increasing evidence that human WDR45 deficiency impairs autophagy, thereby raising the possibility that this rare disorder will offer insights into more common neurodegenerative disorders such as Parkinson or Alzheimer disease

New NBIA subtype: Genetic, clinical, pathologic, and radiographic features of MPAN

Objective: to assess the frequency of mutations in C19orf12 in the greater neurodegeneration with brain iron accumulation (NBIA) population and further characterize the associated phenotype.Methods: samples from 161 individuals with idiopathic NBIA were screened, and C19orf12 mutations were identified in 23 subjects. Direct examinations were completed on 8 of these individuals, and medical records were reviewed on all 23. Histochemical and immunohistochemical studies were performed on brain tissue from one deceased subject.Results: a variety of mutations were detected in this cohort, in addition to the Eastern European founder mutation described previously. The characteristic clinical features of mitochondrial membrane protein-associated neurodegeneration (MPAN) across all age groups include cognitive decline progressing to dementia, prominent neuropsychiatric abnormalities, and a motor neuronopathy. A distinctive pattern of brain iron accumulation is universal. Neuropathologic studies revealed neuronal loss, widespread iron deposits, and eosinophilic spheroidal structures in the basal ganglia. Lewy neurites were present in the globus pallidus, and Lewy bodies and neurites were widespread in other areas of the corpus striatum and midbrain structures.Conclusions: MPAN is caused by mutations in C19orf12 leading to NBIA and prominent, widespread Lewy body pathology. The clinical phenotype is recognizable and distinctive, and joins pantothenate kinase-associated neurodegeneration and PLA2G6-associated neurodegeneration as one of the major forms of NBI

Exome sequencing reveals de novo <em>WDR45</em> mutations causing a phenotypically distinct, x-linked dominant form of NBIA.

Neurodegeneration with brain iron accumulation (NBIA) is a group of genetic disorders characterized by abnormal iron deposition in the basal ganglia. We report that de novo mutations in WDR45, a gene located at Xp11.23 and encoding a beta-propeller scaffold protein with a putative role in autophagy, cause a distinctive NBIA phenotype. The clinical features include early-onset global developmental delay and further neurological deterioration (parkinsonism, dystonia, and dementia developing by early adulthood). Brain MRI revealed evidence of iron deposition in the substantia nigra and globus pallidus. Males and females are phenotypically similar, an observation that might be explained by somatic mosaicism in surviving males and germline or somatic mutations in females, as well as skewing of X chromosome inactivation. This clinically recognizable disorder is among the more common forms of NBIA, and we suggest that it be named accordingly as beta-propeller protein-associated neurodegeneration