Publications by authors named "Tomoko Tsuruoka"

Article Synopsis
  • - The study reports on rare cases of biallelic deletions in the ATPase family AAA-domain containing protein 3A (ATAD3A) gene, which can lead to infantile lethality characterized by conditions like pontocerebellar hypoplasia (PCH) and spinal cord hypoplasia.
  • - Genetic analysis through whole-genome sequencing revealed that these deletions resulted in severe malformations and a significant frameshift, suggesting they likely create a nonfunctional protein (null allele).
  • - Pathological findings in affected infants showed extensive damage to the spinal cord's gray and white matter, indicating that biallelic deletions in the ATAD3A gene should be considered when diagnosing mitochondrial diseases that
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The 8806H formula is the only renal formula available for pediatric patients with chronic kidney disease in Japan. A 1-month-old female infant could not be administered 8806H because of milk allergy. Administration of low-potassium anti-allergic formula treated with sodium polystyrene sulfonate maintained adequate serum potassium levels, and introduction of peritoneal dialysis could be delayed.

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Background: Hypophosphatasia (HPP) is a rare inherited metabolic disorder caused by mutations in the ALPL gene, which encodes tissue nonspecific alkaline phosphatase. The severity of HPP is widely diverse from the perinatal form to the adult mild form. The former represents the most severe form and was earlier associated with high mortality due to pneumonia which was caused by severe hypomineralization of the bones-such as chest deformity and fractured ribs-and muscle weakness.

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Article Synopsis
  • The m.14453G > A mutation in MT-ND6 is linked to mitochondrial conditions like Leigh syndrome, but its full clinical and molecular impact remains unclear.
  • Four infantile patients with this mutation were studied, all showing brainstem and basal ganglia lesions, with some also experiencing heart issues.
  • The study found reduced ND6 protein expression in patient samples, but did not establish a clear link between mutation levels and the age of onset or symptoms, although infantile onset was distinctly associated with Leigh syndrome.
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Article Synopsis
  • - The study analyzed neonatal-onset mitochondrial disease in Japan, focusing on clinical features, molecular diagnosis, and prognosis from a population of 281 patients over a 16-year period.
  • - Results indicated that the most common conditions were multisystem mitochondrial disease, Leigh syndrome, cardiomyopathy, and hepatopathy, with many symptoms appearing within the first two days of life.
  • - Findings emphasized the need for comprehensive biochemical and genetic testing to improve diagnosis rates and enhance understanding of prognosis for these diverse conditions.
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Introduction: Autosomal dominant mitochondrial DNA depletion syndrome (MTDPS-12A) is characterized by severe hypotonia from birth due to a mutation in the adenine nucleotide translocator 1 (ANT1).

Case Report: A 4-year-old female patient diagnosed with neonatal-onset mitochondrial disease, who had good cognitive function while receiving antiepileptic treatment, presented with sudden-onset status epilepticus with facial and limb myoclonus persisting for more than 30 min. Subsequently, she developed epileptic encephalopathy.

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  • Cardiomyopathy is a common issue in pediatric patients with mitochondrial disease, affecting 21% of those studied and linked to higher mortality rates.
  • In a study involving 223 pediatric patients, 38% died over an average follow-up of 36 months, with significant survival differences based on the presence of cardiomyopathy.
  • Key independent risk factors for increased mortality included left ventricular hypertrophy, neonatal onset, and chromosomal aberrations, especially when combined, leading to extremely high mortality rates in those cases.
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  • Prenatal genetic diagnosis of mitochondrial diseases caused by defects in nuclear DNA (nDNA) has been studied in various countries, but not yet in Japan.
  • In a study involving over 400 patients, 13 families sought prenatal diagnosis, with some pregnancies leading to the birth of healthy babies after being diagnosed with benign variants.
  • The findings suggest that severe mitochondrial diseases with potential lethality could benefit from prenatal testing, highlighting the need for careful genetic counseling for families considering their options.
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Background: Hepatocerebral mitochondrial DNA depletion syndrome (MTDPS) is a disease caused by defects in mitochondrial DNA maintenance and leads to liver failure and neurological complications during infancy. Liver transplantation (LT) remains controversial due to poor outcomes associated with extrahepatic symptoms. The purposes of this study were to clarify the current clinical and molecular features of hepatocerebral MTDPS and to evaluate the outcomes of LT in MTDPS patients in Japan.

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The detoxification of ammonia to urea requires a functional hepatic urea cycle, which consists of six enzymes and two mitochondrial membrane transporters. The initial step of the urea cycle is catalyzed by carbamyl phosphate synthetase 1 (CPS1). CPS1 deficiency (CPS1D) is a rare autosomal recessive disorder.

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Leigh syndrome is a major phenotype of mitochondrial diseases in children. With new therapeutic options being proposed, assessing the mortality and clinical condition of Leigh syndrome patients is crucial for evaluating therapeutics. As data are scarce in Japan, we analysed the mortality rate and clinical condition of Japanese Leigh syndrome patients that we diagnosed since 2007.

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Mitochondrial respiratory chain complexes II, III, and IV and cytochrome c contain haem, which is generated by the insertion of Fe into protoporphyrin IX. 5-Aminolevulinic acid (ALA) combined with sodium ferrous citrate (SFC) was reported to enhance haem production, leading to respiratory complex and haem oxygenase-1 (HO-1) upregulation. Here, we investigated the effects of different concentrations of ALA and SFC alone or in combination (ALA/SFC) on fibroblasts from 8 individuals with mitochondrial diseases and healthy controls.

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Leigh syndrome (LS) is a progressive neurodegenerative disorder of infancy and early childhood. It is clinically diagnosed by typical manifestations and characteristic computed tomography (CT) or magnetic resonance imaging (MRI) studies. Unravelling mitochondrial respiratory chain (MRC) dysfunction behind LS is essential for deeper understanding of the disease, which may lead to the development of new therapies and cure.

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Background: Although mitochondrial respiratory chain disorders (MRCD) are one of the most common congenital metabolic diseases, there is no cumulative data on enzymatic diagnosis and clinical manifestation for MRCD in Japan and Asia.

Methods: We evaluated 675 Japanese patients having profound lactic acidemia, or patients having symptoms or signs of multiple-organ origin simultaneously without lactic acidemia on respiratory chain enzyme activity assay and blue native polyacrylamide gel electrophoresis. Quantitative polymerase chain reaction was used to diagnose mitochondrial DNA depletion syndrome (MTDPS).

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Nitric oxide (NO) is synthesized from arginine and O(2) by nitric oxide synthase (NOS). Citrulline, which is formed as a by-product of the NOS reaction, can be recycled to arginine by the 2 enzymes acting in the urea cycle: argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). Although the complete urea cycle is expressed only in the liver, ASS and ASL are expressed in other organs including the kidney and vascular endothelium.

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The etiology of secretory diarrhea in early life is often unclear. We report a Japanese boy who survived until 3 years of age, despite intractable diarrhea commencing soon after birth. The fecal sodium content was strikingly high (109 mmol/L [normal range, 27-35 mmol/L]) and the osmotic gap was decreased (15 mOsm/kg), consistent with the findings of congenital sodium diarrhea.

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