Investigation of the alpha-N-acetylgalactosaminidase activity and protein in the proband revealed less than 2% of normal activity and the absence of detectable immunoreactive enzyme protein, findings comparable to those in the patients with infantile neuroaxonal dystrophy and alpha-N-acetylgalactosaminidase deficiency.
We mapped a locus for infantile neuroaxonal dystrophy (INAD) and neurodegeneration with brain iron accumulation (NBIA) to chromosome 22q12-q13 and identified mutations in PLA2G6, encoding a calcium-independent group VI phospholipase A2, in NBIA, INAD and the related Karak syndrome.
We mapped a locus for infantile neuroaxonal dystrophy (INAD) and neurodegeneration with brain iron accumulation (NBIA) to chromosome 22q12-q13 and identified mutations in PLA2G6, encoding a calcium-independent group VI phospholipase A2, in NBIA, INAD and the related Karak syndrome.
We mapped a locus for infantile neuroaxonal dystrophy (INAD) and neurodegeneration with brain iron accumulation (NBIA) to chromosome 22q12-q13 and identified mutations in PLA2G6, encoding a calcium-independent group VI phospholipase A2, in NBIA, INAD and the related Karak syndrome.
We mapped a locus for infantile neuroaxonal dystrophy (INAD) and neurodegeneration with brain iron accumulation (NBIA) to chromosome 22q12-q13 and identified mutations in PLA2G6, encoding a calcium-independent group VI phospholipase A2, in NBIA, INAD and the related Karak syndrome.
These results indicate that loss of iPLA(2)beta causes age-dependent impairment of axonal membrane homeostasis and protein degradation pathways, leading to age-dependent neurological impairment. iPLA(2)beta-KO mice will be useful for further studies of pathogenesis and experimental interventions in INAD and neurodegeneration with brain iron accumulation.
Previously, children with PLA2G6 mutations have been diagnosed with several different disorders and we wished to better define the phenotype of PLA2G6- associated neurodegeneration.
These findings provide evidence that impairment of iPLA2beta causes neuroaxonal degeneration, and indicate that the iPLA2beta-/- mouse is an appropriate animal model of human neurodegenerative diseases associated with mutations of the iPLA2beta gene, such as infantile neuroaxonal dystrophy and neurodegeneration with brain iron accumulation.
Because of the significantly early onset of the disease, this mouse mutant (Pla2g6-inad) could be highly useful for further studies of pathogenesis and experimental interventions in INAD and neurodegeneration.
PLA2G6 mutations are associated with infantile neuroaxonal dystrophy and have been reported previously to cause early cerebellar signs, and the syndrome was classified as neurodegeneration with brain iron accumulation (type 2).