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Natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration.

ABSTRACT: AIMS:To investigate the natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration. METHODS:We collected data of patients with PKAN by searching from available publications in English and Chinese. Patients diagnosed in our center (Peking University First Hospital) were also included. The difference in natural history and genotype between early-onset (<10 year of age at onset) and late-onset patients (?10 year of age at onset) with PKAN was compared. RESULTS:A total of 248 patients were included. The median age at onset was 3.0 years in the early-onset group and 18.0 years in the late-onset group. Dystonia in lower limbs was the most common initial symptom in both groups. In the early-onset group, the median interval between the disease onset and occurrence of oromandibular dystonia, generalized dystonia, loss of independent ambulance was 6.0 years, 5.0 years, and 5.0 years. The corresponding values in late-onset group were 1.0 year, 4.0 years, and 6.0 years. About 20.0% died at median age of 12.5 years and 9.5 years after the onset in early-onset group. About 2.0% of the late-onset patients died during the follow-up. A total of 176 mutations were identified. Patients carrying two null alleles in PANK2 showed significantly earlier age of disease onset and progressed more rapidly to loss of independent ambulance. CONCLUSIONS:This study provided a comprehensive review on the natural history and genotype of 248 patients with PKAN. The results will serve as a historical control data for future clinical trial on PKAN.

SUBMITTER: Chang X

PROVIDER: S-EPMC7298993 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration.

Chang Xuting X Zhang Jie J Jiang Yuwu Y Wang Jingmin J Wu Ye Y

CNS neuroscience & therapeutics 20200211 7

<h4>Aims</h4>To investigate the natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration.<h4>Methods</h4>We collected data of patients with PKAN by searching from available publications in English and Chinese. Patients diagnosed in our center (Peking University First Hospital) were also included. The difference in natural history and genotype between early-onset (<10 year of age at onset) and late-onset patients (≥10 year of age at onset) with PKAN w ...[more]

PMID: 32043823

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Project description:Pantothenate kinase-associated neurodegeneration (PKAN) is a rare genetic disorder caused by mutations in the mitochondrial pantothenate kinase 2 (PANK2) gene and displays an inherited autosomal recessive pattern. In this study, we identified eight PANK2 mutations, including three novel mutations (c.1103A > G/p.D368G, c.1696C > G/p.L566V, and c.1470delC/p.R490fs494X), in seven unrelated families with PKAN. All the patients showed an eye-of-the-tiger sign on the MRI, six of seven patients had dystonia, and two of seven patients had Parkinsonism. Biallelic mutations of PANK2 decreased PANK2 protein expression and reduced mitochondrial membrane potential in human embryonic kidney (HEK) 293T cells. The biallelic mutations from patients with early-onset PKAN, a severity phenotype, showed decreased mitochondrial membrane potential more than that from late-onset patients. We systematically reviewed all the reported patients with PKAN with PANK2 mutations. The results indicated that the early-onset patients carried a significantly higher frequency of biallelic loss-of-function (LoF) mutations compared to late-onset patients. In general, patients with LoF mutations showed more severe phenotypes, including earlier onset age and loss of gait. Although there was no significant difference in the frequency of biallelic missense mutations between the early-onset and late-onset patients, we found that patients with missense mutations in the mitochondrial trafficking domain (transit peptide/mitochondrial domain) of PANK2 exhibited the earliest onset age when compared to patients with mutations in the other two domains. Taken together, this study reports three novel mutations and indicates a correlation between the phenotype and mitochondrial dysfunction. This provides new insight for evaluating the clinical severity of patients based on the degree of mitochondrial dysfunction and suggests genetic counseling not just generalized identification of mutated PANK2 in clinics.

Project description:Neurodegeneration with brain iron accumulation is a broad term that describes a heterogeneous group of progressive and invalidating neurologic disorders in which iron deposits in certain brain areas, mainly the basal ganglia. The predominant clinical symptoms include spasticity, progressive dystonia, Parkinson's disease-like symptoms, neuropsychiatric alterations, and retinal degeneration. Among the neurodegeneration with brain iron accumulation disorders, the most frequent subtype is pantothenate kinase-associated neurodegeneration (PKAN) caused by defects in the gene encoding the enzyme pantothenate kinase 2 (PANK2) which catalyzed the first reaction of the coenzyme A biosynthesis pathway. Currently there is no effective treatment to prevent the inexorable course of these disorders. The aim of this review is to open up a discussion on the utility of using cellular models derived from patients as a valuable tool for the development of precision medicine in PKAN. Recently, we have described that dermal fibroblasts obtained from PKAN patients can manifest the main pathological changes of the disease such as intracellular iron accumulation accompanied by large amounts of lipofuscin granules, mitochondrial dysfunction and a pronounced increase of markers of oxidative stress. In addition, PKAN fibroblasts showed a morphological senescence-like phenotype. Interestingly, pantothenate supplementation, the substrate of the PANK2 enzyme, corrected all pathophysiological alterations in responder PKAN fibroblasts with low/residual PANK2 enzyme expression. However, pantothenate treatment had no favourable effect on PKAN fibroblasts harbouring mutations associated with the expression of a truncated/incomplete protein. The correction of pathological alterations by pantothenate in individual mutations was also verified in induced neurons obtained by direct reprograming of PKAN fibroblasts. Our observations indicate that pantothenate supplementation can increase/stabilize the expression levels of PANK2 in specific mutations. Fibroblasts and induced neurons derived from patients can provide a useful tool for recognizing PKAN patients who can respond to pantothenate treatment. The presence of low but significant PANK2 expression which can be increased in particular mutations gives valuable information which can support the treatment with high dose of pantothenate. The evaluation of personalized treatments in vitro of fibroblasts and neuronal cells derived from PKAN patients with a wide range of pharmacological options currently available, and monitoring its effect on the pathophysiological changes, can help for a better therapeutic strategy. In addition, these cell models will be also useful for testing the efficacy of new therapeutic options developed in the future.

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Natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration.

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Natural history and genotype-phenotype correlation of pantothenate kinase-associated neurodegeneration.

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