A novel mutation in a patient with pantothenate kinase-associated neurodegeneration

Incidence of PKAN determined by bioinformatic and population-based analysis of ~140,000 humans

Panthothenate kinase-associated neurodegeneration (PKAN, OMIM 234200), is an inborn is an autosomal recessive inborn error of metabolism caused by pathogenic variants in PANK2. PANK2 encodes the enzyme pantothenate kinase 2 (EC 2.7.1.33), an essential regulatory enzyme in CoA biosynthesis. Clinical presentation includes dystonia, rigidity, bradykinesia, dysarthria, pigmentary retinopathy and dementia with variable age of onset ranging from childhood to adulthood. In order to provide an accurate incidence estimate of PKAN, we conducted a systematic review of the literature and databases for pathogenic mutations and constructed a bioinformatic profile for pathogenic missense variants in PANK2. We then studied the gnomAD cohort of ~140,000 unrelated adults from global populations to determine the allele frequency of the variants in PANK2 reported pathogenic for PKAN and for those additional variants identified in gnomAD that met bioinformatics criteria for being potentially pathogenic. Incidence was estimated based on three different models using the allele frequencies of pathogenic PKAN variants with or without those bioinformatically determined to be potentially pathogenic. Disease incidence calculations showed PKAN incidence ranging from 1:396,006 in Europeans, 1:1,526,982 in Africans, 1:480,826 in Latino, 1:523,551 in East Asians and 1:531,118 in South Asians. These results indicate PKAN is expected to occur in approximately 2 of every 1 million live births globally outside of Africa, and has a much lower incidence 1 in 1.5 million live births in the African population.

Characteristics of TIA and its management in a tertiary care hospital in Pakistan

BACKGROUND

Transient ischemic attack (TIA) is described as a brief episode of neurological dysfunction caused by focal brain ischemia, with clinical symptoms typically lasting less than an hour, and without evidence of acute infarction. Recent studies depict TIA as a particularly unstable condition. Risk of stroke is greater than 10% in the first 90 days after an index TIA. The presentation, prognosis and intervention for TIA have not been reported in South-Asians in a developing country.

METHOD

A retrospective chart review was done for 158 patients who were admitted with the diagnosis of TIA, as defined by ICD 9 code 435, from January 2003 to December 2005 at the Aga Khan University Hospital, Karachi, Pakistan. The data was entered and analyzed in SPSS version 14.0.

FINDINGS

Among 158 patients, 57.6% were male and 41.1% were female. The common presenting symptoms were motor symptoms (51.3%), speech impairment (43%), sensory impairment (34.8%) and loss of balance/vertigo (29.1%). The median delay in presenting to the hospital was 4 hours. Those with motor symptoms were found to present earlier. The study showed that only 60.8% of all the patients presenting with TIA received any immediate treatment out of which 44.7% received aspirin. Neuroimaging was used in 91.1% of the patients. Of all the TIA patients 9.1% converted to stroke with 50% doing so within the first 24 hours.

CONCLUSION

The natural history of TIA from this developing nation is comparable to international descriptions. A large percentage of patients are still not receiving any immediate treatment as recommended in available guidelines, even in a tertiary care hospital.

Novel mutation in the PANK2 gene leads to pantothenate kinase-associated neurodegeneration in a Pakistani family

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.

PANK2 gene analysis confirms genetic heterogeneity in neurodegeneration with brain iron accumulation (NBIA) but mutations are rare in other types of adult neurodegenerative disease

Mutations in the pantothenate kinase 2 gene (PANK2) are the cause of pantothenate kinase associated neurodegeneration (PKAN), an autosomal recessive (AR) disorder characterized by motor symptoms as such as dystonia or parkinsonism, mental retardation, retinitis pigmentosa and iron accumulation in the brain. As many neurodegenerative conditions have similar clinical features we screened a number of adult and childhood onset movement disorders for PANK2 mutation. This included cases with neurodegeneration and brain iron accumulation, corticobasal degeneartion, progressive supranuclear palsy (PSP), Parkinson's disease (PD), multiple system atropy, giant axonal neuropathy (GAN), neuroaxonal dystrophy (NAD), Guam dementia and HARP syndrome (pallido-pyramidal syndrome and hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa and pallidal degeneration). From our series of patients one patient with PKAN and a progressive severe dystonic syndrome, cerebellar ataxia, retinitis pigmentosa and eventual anarthria had a novel combination of two compound heterozygote mutations identified in the PANK2 gene, G-->A transition at base 1238 (G411R) and a C-->A transition at base 1184 (A395E). In the patient with HARP syndrome two compound heterozygote mutations (Met327Thr and IVS5-1 G to T) in the PANK2 gene were found. No other mutations were found in any of the other patient groups, suggesting that PANK2 mutations are not associated with the aetiology of these adult degenerative conditions and confirms the genetic heterogeneity in neurodegeneration with brain iron accumulation.