Neurodegeneration associated with genetic defects in phospholipase A(2)

Department of Molecular and Medical Genetics, Oregon Health & Science University, L103a, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA.
Neurology (Impact Factor: 8.3). 10/2008; 71(18):1402-9. DOI: 10.1212/01.wnl.0000327094.67726.28
Source: PubMed

ABSTRACT Mutations in the gene encoding phospholipase A(2) group VI (PLA2G6) are associated with two childhood neurologic disorders: infantile neuroaxonal dystrophy (INAD) and idiopathic neurodegeneration with brain iron accumulation (NBIA). INAD is a severe progressive psychomotor disorder in which axonal spheroids are found in brain, spinal cord, and peripheral nerves. High globus pallidus iron is an inconsistent feature of INAD; however, it is a diagnostic criterion of NBIA, which describes a clinically and genetically heterogeneous group of disorders that share this hallmark feature. We sought to delineate the clinical, radiographic, pathologic, and genetic features of disease resulting from defective phospholipase A(2).
We identified 56 patients clinically diagnosed with INAD and 23 with idiopathic NBIA and screened their DNA for PLA2G6 mutations.
Eighty percent of patients with INAD had mutations in PLA2G6, whereas mutations were found in only 20% of those with idiopathic NBIA. All patients with two null mutations had a more severe phenotype. On MRI, nearly all mutation-positive patients had cerebellar atrophy, and half showed brain iron accumulation. We observed Lewy bodies and neurofibrillary tangles in association with PLA2G6 mutations.
Defects in phospholipase A(2) lead to a range of phenotypes. PLA2G6 mutations are associated with nearly all cases of classic infantile neuroaxonal dystrophy but a minority of cases of idiopathic neurodegeneration with brain iron accumulation, and genotype correlates with phenotype. Cerebellar atrophy predicts which patients are likely to be mutation-positive. The neuropathologic changes that are caused by defective phospholipase A(2) suggest a shared pathogenesis with both Parkinson and Alzheimer diseases.

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Available from: Cristina Dias, Aug 16, 2015
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    • "'Neurodegeneration with Brain Iron Accumulation' (NBIA) encompasses a group of disorders characterised by progressive motor symptoms , neurological regression and radiologically discernible brain iron accumulation [1] [2] [3] [4]. The major childhood NBIA syndromes include pantothenate kinase associated neurodegeneration (PKAN; MIM#234200) [5], fatty acid hydroxylase associated neurodegeneration (FAHN; MIM#612319) [6], mitochondrial membrane protein associated neurodegeneration (MPAN; MIM#614298) [7], beta-propeller protein associated neurodegeneration (BPAN; MIM#300894) [8], and phospholipase A 2 associated neurodegeneration (PLAN; MIM#256600). "
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    ABSTRACT: Phospholipase A2 associated neurodegeneration (PLAN) is a major phenotype of autosomal recessive Neurodegeneration with Brain Iron Accumulation (NBIA). We describe the clinical phenotypes, neuroimaging features and PLA2G6 mutations in 5 children, of whom 4 presented with infantile neuroaxonal dystrophy (INAD). One other patient was diagnosed with the onset of PLAN in childhood, and our report highlights the diagnostic challenges associated with this atypical PLAN subtype. In this series, the neuroradiological relevance of the classical PLAN features as well as ‘apparent claval hypertrophy’ is explored. Novel PLA2G6 mutations were identified in all patients. PLAN should be considered not only in patients presenting with a classic INAD phenotype but also in older patients presenting later in childhood with non-specific progressive neurological features including social communication difficulties, gait disturbance, dyspraxia, neuropsychiatric symptoms and extrapyramidal motor features.
    Molecular Genetics and Metabolism 06/2014; 112(2). DOI:10.1016/j.ymgme.2014.03.008 · 2.83 Impact Factor
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    • "The hallmark of this disease is the eyeof-the-tiger signal in the globus pallidus on T 2 -weighted MRI (Hayflick et al., 2003; Gregory et al., 2009) To date, the mechanistic connection linking PANK2 dysfunction, neurodegeneration and alteration of iron homeostasis has not been understood, thus preventing our comprehension of the pathogenesis of the disease and the design of efficient therapeutic strategies. It has been proposed that reduced PANK2 enzymatic activity determines the accumulation of cysteine, which may chelate iron thus promoting the formation of free radicals (Gregory et al., 2008); alternatively, defects in co-enzyme A and, as a consequence, in phospholipid metabolism may damage the membranes and lead to increased oxidative stress, which may alter iron homeostasis (Leonardi et al., 2007). "
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    ABSTRACT: Pantothenate kinase-associated neurodegeneration, caused by mutations in the PANK2 gene, is an autosomal recessive disorder characterized by dystonia, dysarthria, rigidity, pigmentary retinal degeneration and brain iron accumulation. PANK2 encodes the mitochondrial enzyme pantothenate kinase type 2, responsible for the phosphorylation of pantothenate or vitamin B5 in the biosynthesis of co-enzyme A. A Pank2 knockout (Pank2(-/-)) mouse model did not recapitulate the human disease but showed azoospermia and mitochondrial dysfunctions. We challenged this mouse model with a low glucose and high lipid content diet (ketogenic diet) to stimulate lipid use by mitochondrial beta-oxidation. In the presence of a shortage of co-enzyme A, this diet could evoke a general impairment of bioenergetic metabolism. Only Pank2(-/-) mice fed with a ketogenic diet developed a pantothenate kinase-associated neurodegeneration-like syndrome characterized by severe motor dysfunction, neurodegeneration and severely altered mitochondria in the central and peripheral nervous systems. These mice also showed structural alteration of muscle morphology, which was comparable with that observed in a patient with pantothenate kinase-associated neurodegeneration. We here demonstrate that pantethine administration can prevent the onset of the neuromuscular phenotype in mice suggesting the possibility of experimental treatment in patients with pantothenate kinase-associated neurodegeneration.
    Brain 12/2013; 137(1). DOI:10.1093/brain/awt325 · 10.23 Impact Factor
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    • "Mutations of PLA2G6 cause most cases of human INAD (Gregory et al., 2008), but how these cause NAD is unknown. The recessive nature of human INAD and canine FNAD indicates that, in both instances, mutations cause a loss of gene function. "
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    ABSTRACT: Neuroaxonal dystrophy in brainstem, spinal cord tracts, and spinal nerves accompanied by cerebellar hypoplasia was observed in a colony of laboratory dogs. Fetal akinesia was documented by ultrasonographic examination. At birth, affected puppies exhibited stereotypical positioning of limbs, scoliosis, arthrogryposis, pulmonary hypoplasia, and respiratory failure. Regional hypoplasia in the central nervous system was apparent grossly, most strikingly as underdeveloped cerebellum and spinal cord. Histopathologic abnormalities included swollen axons and spheroids in brainstem and spinal cord tracts; reduced cerebellar foliation, patchy loss of Purkinje cells, multifocal thinning of the external granular cell layer, and loss of neurons in the deep cerebellar nuclei; spheroids and loss of myelinated axons in spinal roots and peripheral nerves; increased myocyte apoptosis in skeletal muscle; and fibrofatty connective tissue proliferation around joints. Breeding studies demonstrated that the canine disorder is a fully penetrant, simple autosomal recessive trait. The disorder demonstrated a type and distribution of lesions homologous to that of human infantile neuroaxonal dystrophy (INAD), most commonly caused by mutations of phospholipase A2 group VI gene (PLA2G6), but alleles of informative markers flanking the canine PLA2G6 locus did not associate with the canine disorder. Thus, fetal-onset neuroaxonal dystrophy in dogs, a species with well-developed genome mapping resources, provides a unique opportunity for additional disease gene discovery and understanding of this pathology.
    The Journal of Comparative Neurology 09/2010; 518(18):3771-84. DOI:10.1002/cne.22423 · 3.51 Impact Factor
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