PO19-WE-05 Linkage analysis and mutation screening in PANK2 and PLA2G6 genes in 7 consanguineous Saudi Arabian families with Karak syndrome (original) (raw)
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BMC Medical Genetics, 2017
Background: Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous group of disorders associated with progressive impairment of movement, vision, and cognition. The disease is initially diagnosed on the basis of changes in brain magnetic resonance imaging which indicate an abnormal brain iron accumulation in the basal ganglia. However, the diagnosis of specific types should be based on both clinical findings and molecular genetic testing for genes associated with different types of NBIA, including PANK2, PLA2G6, C19orf12, FA2H, ATP13A2, WDR45, COASY, FTL, CP, and DCAF17. The purpose of this study was to investigate disease-causing mutations in two patients with distinct NBIA disorders. Case presentation: Whole Exome sequencing using Next Generation Illumina Sequencing was used to enrich all exons of protein-coding genes as well as some other important genomic regions in these two affected patients. A deleterious homozygous four-nucleotide deletion causing frameshift deletion in PANK2 gene (c.1426_1429delATGA, p.M476 fs) was identified in an 8 years old girl with dystonia, bone fracture, muscle rigidity, abnormal movement, lack of coordination and chorea. In addition, our study revealed a novel missense mutation in PLA2G6 gene (c.3G > T:p.M1I) in one and halfyear-old boy with muscle weakness and neurodevelopmental regression (speech, motor and cognition). The novel mutations were also confirmed by Sanger sequencing in the proband and their parents. Conclusions: Current study uncovered two rare novel mutations in PANK2 and PLA2G6 genes in patients with NBIA disorder and such studies may help to conduct genetic counseling and prenatal diagnosis more accurately for individuals at the high risk of these types of disorders.
Annals of Neurology, 2006
Objective: Neurodegeneration with brain iron accumulation (NBIA) is a group of disorders characterized by magnetic resonance imaging (MRI) changes in basal ganglia. Both missense and nonsense mutations have been found in such patients in a gene encoding the mitochondrial pantothenate kinase (PANK2). Methods: We completed a mutation screen in 72 patients with the diagnosis NBIA based on clinical findings and radiological imaging. The entire coding region of the PANK2 gene (20p12.3) was investigated for point mutations and deletions. Results: We uncovered both mutant alleles in 48 patients. Deletions accounted for 4% of mutated alleles. Patients with two loss-of-function alleles (n ؍ 11) displayed symptoms always at an early stage of life. In the presence of missense mutations (n ؍ 37), the age of onset correlated with residual activity of the pantothenate kinase. Progression of disease measured by loss of ambulation was variable in both groups. We did not observe a strict correlation between the eye-of-the-tiger sign and PANK2 mutations. In 24 patients, no PANK2 mutation was identified. Interpretation: Deletion screening of PANK2 should be part of the diagnostic spectrum. Factors other than enzymatic residual activity are determining the course of disease. There are strong arguments in favor of locus heterogeneity.
Scientific Reports
Pantothenate kinase-associated neurodegeneration is a rare hereditary neurodegenerative disorder associated with nucleotide variation(s) in mitochondrial human Pantothenate kinase 2 (hPanK2) protein encoding PANK2 gene, and is characterized by symptoms of extra-pyramidal dysfunction and accumulation of non-heme iron predominantly in the basal ganglia of the brain. In this study, we describe a familial case of PKAN from the State of Jammu and Kashmir (J&K), India based on the clinical findings and genetic screening of two affected siblings born to consanguineous normal parents. The patients present with early-onset, progressive extrapyramidal dysfunction, and brain Magnetic Resonance imaging (MRI) suggestive of symmetrical iron deposition in the globus pallidi. Screening the PANK2 gene in the patients as well as their unaffected family members revealed a functional single nucleotide variation, perfectly segregating in the patient's family in an autosomal recessive mode of inheritance. We also provide the results of in-silico analyses, predicting the functional consequence of the identified PANK2 variant. Pantothenate Kinase-Associated Neurodegeneration (PKAN; OMIM# 234200) is a rare autosomal recessive, progressive neurodegenerative movement disorder characterized by accumulation of non-heme iron in the brain, predominantly in the bilateral globus pallidus region of the basal ganglia 1-3. Also known as Neurodegeneration with Brain Iron Accumulation (NBIA) Type-1 (NBIA-1), it belongs to a spectrum of inherited neurodegenerative disorders, namely NBIA that shares a common detectable feature of iron deposition in basal ganglia on the brain MRI of the patients. Being the most common type of NBIA, PKAN accounts nearly 30-50% of the global NBIA cases with an estimated global prevalence of about 1 to 3 in one million individuals 3, 4. The age-of-onset of symptoms is from infancy to late adulthood with variable rate of progression and severity of the motor symptoms, based on which the disorder is clinically classified into two phenotypes-a "classic or typical or early-onset PKAN" with a rapid progression and clinically homogenous phenotype in majority of the cases and "atypical or late-onset PKAN" with a slower progression and variable clinical phenotypes 4, 5. Further, both familial and sporadic cases of PKAN are known 6, 7. The diagnosis of PKAN is generally established on patient's clinical, radiological as well as genetic backgrounds. The main clinical feature includes progressive neurodegeneration due to non-heme iron overload in
2006
Neurodegenerative disorders with high brain iron include Parkinson disease, Alzheimer disease and several childhood genetic disorders categorized as neuroaxonal dystrophies. 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 A 2 , in NBIA, INAD and the related Karak syndrome. This discovery implicates phospholipases in the pathogenesis of neurodegenerative disorders with iron dyshomeostasis.
PLA2G6, encoding a phospholipase A2, is mutated in neurodegenerative disorders with high brain iron
Nature Genetics, 2006
Neurodegenerative disorders with high brain iron include Parkinson disease, Alzheimer disease and several childhood genetic disorders categorized as neuroaxonal dystrophies. 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 A 2 , in NBIA, INAD and the related Karak syndrome. This discovery implicates phospholipases in the pathogenesis of neurodegenerative disorders with iron dyshomeostasis.
Early-onset neurodegeneration with brain iron accumulation due to PANK2 mutation
Brain and Development, 2012
Background: Pantothenate kinase-associated neurodegeneration (PKAN) is a neurodegenerative disorder caused by pantothenate kinase (PANK2) gene mutations. Brain magnetic resonance imaging (MRI) typically shows the "eye-of-the-tiger" sign, i.e. bilateral pallidal T2 hypointensity with a small central region of T2-hyperintensity. Aims: To describe clinical and MRI findings of a boy with early-onset neurodegeneration with brain iron accumulation due to PANK2 mutation. Methods: Clinical, neuroradiological and molecular investigations have been performed. Results: At first observation (2 years and 10 months) the boy presented only with developmental delay and toe-walking and isolated T2 hyperintensity within globi pallidi on brain MRI. One year later, small rounded areas of markedly low signal within the globi pallidi on T2 * -weighted images appeared in association with mild dystonia. PANK2 gene homozygous mutation confirmed the diagnosis of PKAN. Conclusions: In young children, PKAN should be suspected also before clinical and neuroradiological picture is fully indicative, to avoid delayed diagnosis of a genetic disease for which therapeutical options could be potentially useful if administered in paucisymptomatic subjects.
Pediatric Neurology, 2007
Pantothenate kinase-associated neurodegeneration is an autosomal-recessive disorder associated with the accumulation of iron in the basal ganglia. The disease presents with dystonia, rigidity, and gait impairment, leading to restriction of activities and loss of ambulation. The disorder is caused by defective iron metabolism associated with mutations in the PANK2 gene, which codes for the pantothenate kinase enzyme. We report on a mutation screen conducted in two siblings to establish a molecular diagnosis of the disease and a genetic test for the family.
PLA2G6 gene mutation and infantile neuroaxonal degeneration; report of three cases from Iran
Iranian Journal of Basic Medical Sciences, 2021
Objective(s): Infantile neuroaxonal degeneration (INAD) is a rare subgroup of neurodegeneration with brain iron accumulation (NBIA) disorders. This progressive disorder may develop during the early years of life. Affected individuals mostly manifest developmental delay and/or psychomotor regression as well as other neurological deficits. In the present study, we discussed 3 INAD patients diagnosed before the age of 10 by using Whole-Exome Sequencing (WES). Materials and Methods: We evaluated 3 pediatric patients with clinical phenotypes of INAD who underwent WES. Sanger sequencing was performed for co-segregation analysis of the variants in the families. An in-silico study was conducted for identification of the molecular function of the identified genetic variants in the PLA2G6 gene. Results: We detected three novel genetic variants in the PLA2G6 gene including a homozygous missense (NM_003560.2; c.1949T>C; p.Phe650Ser), a splicing (NM_001349864; c.1266-1G>A) and a frameshift...