RESUMEN
BACKGROUND: Kearns-Sayre Syndrome (KSS) and Pearson Marrow-Pancreas Syndrome (PMPS) are among the classic phenotypes caused by mitochondrial DNA (mtDNA) deletions. KSS is a rare mitochondrial disease defined by a classic triad of progressive external ophthalmoplegia, atypical pigmentary retinopathy, and onset before 20 years. PMPS presents in the first year of life with bone marrow failure and exocrine pancreatic dysfunction, and can evolve into KSS later in life. Even though an mtDNA deletion is the most frequent mutation in KSS and PMPS, cases of duplications and molecular rearrangements have also been described. In Colombia, few case reports of KSS and PMPS have been published in indexed journals or have been registered in scientific events. METHODS: We discuss clinical and genetic aspects of two case reports of pediatric female patients, with initial clinical diagnosis of PMPS who later evolved into KSS, with confirmatory molecular studies of an mtDNA deletion and an mtDNA duplication. RESULTS: A large-scale mtDNA deletion, NC_012920.1:m.8286_14416del, was confirmed by Southern Blot in patient 1. An mtDNA duplication of 7.9 kb was confirmed by MLPA in patient 2. CONCLUSIONS: Our findings are compatible with the phenotypic and genetic presentation of PMPS and KSS. We present the first molecularly confirmed case reports of Colombian patients, diagnosed initially with PMPS, who later evolved to KSS.
Asunto(s)
Síndromes Congénitos de Insuficiencia de la Médula Ósea/genética , ADN Mitocondrial/genética , Síndrome de Kearns-Sayre/genética , Errores Innatos del Metabolismo Lipídico/genética , Enfermedades Mitocondriales/genética , Enfermedades Musculares/genética , Niño , Síndromes Congénitos de Insuficiencia de la Médula Ósea/patología , Diagnóstico Diferencial , Femenino , Duplicación de Gen , Humanos , Síndrome de Kearns-Sayre/patología , Errores Innatos del Metabolismo Lipídico/patología , Enfermedades Mitocondriales/patología , Enfermedades Musculares/patología , Fenotipo , Eliminación de SecuenciaRESUMEN
Mitochondria both produce the energy of the cell as ATP via respiration and regulate cellular metabolism. Accordingly, any deletion or mutation in the mitochondrial DNA (mtDNA) may result in a disease. One of these diseases is Kearns Sayre syndrome (KSS), described for the first time in 1958, where different large-scale deletions of different sizes and at different positions have been reported in the mitochondrial genome of patients with similar clinical symptoms. In this study, sequences of the mitochondrial genome of three patients with clinic features of KSS were analyzed. Our results revealed the position, heteroplasmy percentage, size of deletions, and their haplogroups. Two patients contained deletions reported previously and one patient showed a new deletion not reported previously. These results display for the first time a systematic analysis of mtDNA variants in the whole mtDNA genome of patients with KSS to help to understand their association with the disease.
Asunto(s)
ADN Mitocondrial/genética , Genoma Mitocondrial/genética , Síndrome de Kearns-Sayre/genética , Eliminación de Secuencia/genética , Adolescente , Adulto , Niño , Femenino , Eliminación de Gen , Humanos , Masculino , Mitocondrias/genética , Mutación/genética , Adulto JovenRESUMEN
The genetic diagnosis algorithm for mitochondrial (mt) diseases starts looking for deletions and common mutations in mtDNA. MtDNA's special features, such as large and variable genome copies, heteroplasmy, polymorphisms, and its duplication in the nuclear genome as pseudogenes (NUMTs), make it vulnerable to diagnostic misleading interpretations. Multiplex Ligation-dependent Probe Amplification (MLPA) is used to detect copy number variations in nuclear genes and its application on mtDNA has not been widely spread. We report three Kearns Sayre Syndrome patients and one Chronic Progressive External Ophthalmoplegia adult, whose diagnostic mtDNA deletions were detected by MLPA using a very low amount of DNA. This managed to "dilute" the NUMT interference as well as enhance MLPA's efficiency. By this report, we conclude that when MLPA is performed upon a reduced amount of DNA, it can detect effectively mtDNA deletions. We propose MLPA as a possible first step method in the diagnosis of mt diseases.
Asunto(s)
ADN Mitocondrial/genética , Genoma Mitocondrial/genética , Reacción en Cadena de la Polimerasa Multiplex/métodos , Algoritmos , Variaciones en el Número de Copia de ADN/genética , Humanos , Síndrome de Kearns-Sayre/genética , Enfermedades Mitocondriales/genéticaRESUMEN
Mitochondrial DNA mutations have been associated with different illnesses in humans, such as Kearns-Sayre syndrome (KSS), which is related to deletions of different sizes and positions among patients. Here, we report a Mexican patient with typical features of KSS containing a novel deletion of 7629 bp in size with 85% heteroplasmy, which has not been previously reported. Sequence analysis revealed 3-bp perfect short direct repeats flanking the deletion region, in addition to 7-bp imperfect direct repeats within 9-10 bp. Furthermore, sequencing, alignment and phylogenetic analysis of the hypervariable region revealed that the patient may belong to a founder Native American haplogroup C4c.
Asunto(s)
ADN Mitocondrial/genética , Genes Mitocondriales/genética , Indígenas Norteamericanos/genética , Síndrome de Kearns-Sayre/genética , Filogenia , Eliminación de Secuencia/genética , Secuencia de Bases , Southern Blotting , Encéfalo/diagnóstico por imagen , Niño , Cartilla de ADN/genética , Femenino , Humanos , Síndrome de Kearns-Sayre/patología , Funciones de Verosimilitud , México , Modelos Genéticos , Datos de Secuencia Molecular , Secuencias Repetitivas de Ácidos Nucleicos/genética , Alineación de Secuencia , Análisis de Secuencia de ADN , Tomografía Computarizada por Rayos XRESUMEN
OBJECTIVE: To describe the clinical data and the results of molecular analyses of the mitochondrial DNA in a patient with Kearns-Sayre Syndrome. METHODS: Molecular analyses of mitochondrial DNA from the patient included PCR amplification of a region where the common Kearns- Sayre deletion is located and Genotype-Phenotype correlations are discussed. RESULTS: The affected patient showed ptosis, progressive external ophthalmoplegia, pigmentary changes in the peripheral retina and right bundle block. Molecular analysis disclosed a approximately 5 kb deletion in the mitochondrial DNA and some wild type mtDNA indicating heteroplasmy. CONCLUSIONS: Molecular analysis of mitochondrial DNA confirmed the clinical diagnosis of Kearns-Sayre syndrome. PCR provides a rapid method to identify the common 4997 bp deletion in Kearns-Sayre syndrome. In such cases, PCR diagnosis could avoid invasive methods such as muscle biopsy or spinal tap.
Asunto(s)
ADN Mitocondrial , Eliminación de Gen , Síndrome de Kearns-Sayre/genética , Reacción en Cadena de la Polimerasa , Adolescente , Blefaroptosis/genética , Femenino , Humanos , Oftalmoplejía/genéticaRESUMEN
We present a boy of eight years of age with symptoms of Kearns-Sayre syndrome (KSS) characterised by ophthalmoparesis, palpebral ptosis, mitochondrial myopathy, pigmentous retinitis, associated to short stature, cerebellar signs, cardiac blockade, diabetes melitus, elevated cerebrospinal fluid protein concentration, and focal hand and foot dystonia. The skeletal muscle biopsy demonstrated ragged red fibers, cytochrome C oxidase-negative and succinate dehydrogenase-positive fibers. The magnetic resonance imaging showed symmetrical signal alteration in tegmentum of brain stem, pallidum and thalamus. Mitochondrial DNA analysis from skeletal muscle showed a deletion in heteroplasmic condition. The association of dystonia to KSS, confirmed by molecular analysis, is first described in this case, and the importance of oxidative phosphorylation defects in the physiopathogenesis of this type of movement disorder is stressed.
Asunto(s)
Humanos , Masculino , Niño , Anciano , Distonía/etiología , Síndrome de Kearns-Sayre/genética , ADN Mitocondrial/análisis , ADN Mitocondrial/genética , Distonía/complicaciones , Distonía/fisiopatología , Eliminación de Gen , Síndrome de Kearns-Sayre/patología , Imagen por Resonancia MagnéticaRESUMEN
We present a boy of eight years of age with symptoms of Kearns-Sayre syndrome (KSS) characterised by ophthalmoparesis, palpebral ptosis, mitochondrial myopathy, pigmentous retinitis, associated to short stature, cerebellar signs, cardiac blockade, diabetes mellitus, elevated cerebrospinal fluid protein concentration, and focal hand and foot dystonia. The skeletal muscle biopsy demonstrated ragged red fibers, cytochrome C oxidase-negative and succinate dehydrogenase-positive fibers. The magnetic resonance imaging showed symmetrical signal alteration in tegmentum of brain stem, pallidum and thalamus. Mitochondrial DNA analysis from skeletal muscle showed a deletion in heteroplasmic condition. The association of dystonia to KSS, confirmed by molecular analysis, is first described in this case, and the importance of oxidative phosphorylation defects in the physiopathogenesis of this type of movement disorder is stressed.
Asunto(s)
Distonía/etiología , Síndrome de Kearns-Sayre/complicaciones , Anciano , Niño , ADN Mitocondrial/análisis , ADN Mitocondrial/genética , Distonía/fisiopatología , Eliminación de Gen , Humanos , Síndrome de Kearns-Sayre/genética , Síndrome de Kearns-Sayre/patología , Imagen por Resonancia Magnética , MasculinoRESUMEN
We report herein on eleven Brazilian patients with mitochondrial DNA (mtDNA) deletions, found among thirteen patients with chronic progressive external ophthalmoplegia (CPEO) and ragged-red fibers (RRF). The molecular data was correlated with the morphological and clinical findings. The muscle biopsies were studied by histochemistry, immunohistochemistry and DNA analysis. Muscle mtDNA deletions were mapped and quantitated by Southern blot analysis, polymerase chain reaction and sequencing. Of the eleven patients, ten had CPEO without multisystemic involvement and one had Kearns-Sayre syndrome. Three patients had multiple deletions, two of them with no apparent family history. Eight patients showed heteroplasmic single deletions, ranging in length from 2309 to 7566 bp; three of them had the same 'common deletion' of 4977 bp. The proportion of deleted mtDNA ranged from 14 to 89%. Immunohistochemical studies revealed decreased reactivity with the mtDNA-encoded subunit II of cytochrome c oxidase (COX) in all patients, but preserved activity with the nuclear-encoded COX subunit IV in COX-deficient fibers. Two cases presented a few COX-negative fibers with reduced COX IV immunostaining. We found a high frequency of mtDNA deletions in Brazilian patients with CPEO. There was no correlation between clinical severity, morphological findings and the size or amount of the mutated mtDNA in muscle, suggesting that there are still unknown factors influencing the disease phenotype.