Polygenic effects on the risk of Alzheimer's disease in the Japanese population.

BACKGROUND: Polygenic effects have been proposed to account for some disease phenotypes; these effects are calculated as a polygenic risk score (PRS). This score is correlated with Alzheimer's disease (AD)-related phenotypes, such as biomarker abnormalities and brain atrophy, and is associated with conversion from mild cognitive impairment (MCI) to AD. However, the AD PRS has been examined mainly in Europeans, and owing to differences in genetic structure and lifestyle, it is unclear whether the same relationships between the PRS and AD-related phenotypes exist in non-European populations. In this study, we calculated and evaluated the AD PRS in Japanese individuals using genome-wide association study (GWAS) statistics from Europeans. METHODS: In this study, we calculated the AD PRS in 504 Japanese participants (145 cognitively unimpaired (CU) participants, 220 participants with late mild cognitive impairment (MCI), and 139 patients with mild AD dementia) enrolled in the Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI) project. In order to evaluate the clinical value of this score, we (1) determined the polygenic effects on AD in the J-ADNI and validated it using two independent cohorts (a Japanese neuropathology (NP) cohort (n = 565) and the North American ADNI (NA-ADNI) cohort (n = 617)), (2) examined the AD-related phenotypes associated with the PRS, and (3) tested whether the PRS helps predict the conversion of MCI to AD. RESULTS: The PRS using 131 SNPs had an effect independent of APOE. The PRS differentiated between CU participants and AD patients with an area under the curve (AUC) of 0.755 when combined with the APOE variants. Similar AUC was obtained when PRS calculated by the NP and NA-ADNI cohorts was applied. In MCI patients, the PRS was associated with cerebrospinal fluid phosphorylated-tau levels (ß estimate = 0.235, p value = 0.026). MCI with a high PRS showed a significantly increased conversion to AD in APOE ε4 noncarriers with a hazard rate of 2.22. In addition, we also developed a PRS model adjusted for LD and observed similar results. CONCLUSIONS: We showed that the AD PRS is useful in the Japanese population, whose genetic structure is different from that of the European population. These findings suggest that the polygenicity of AD is partially common across ethnic differences.

Plant GARDEN: a portal website for cross-searching between different types of genomic and genetic resources in a wide variety of plant species.

BACKGROUND: Plant genome information is fundamental to plant research and development. Along with the increase in the number of published plant genomes, there is a need for an efficient system to retrieve various kinds of genome-related information from many plant species across plant kingdoms. Various plant databases have been developed, but no public database covers both genomic and genetic resources over a wide range of plant species. MAIN BODY: We have developed a plant genome portal site, Plant GARDEN (Genome And Resource Database Entry: https://plantgarden.jp/en/index ), to provide diverse information related to plant genomics and genetics in divergent plant species. Elasticsearch is used as a search engine, and cross-keyword search across species is available. Web-based user interfaces (WUI) for PCs and tablet computers were independently developed to make data searches more convenient. Several types of data are stored in Plant GARDEN: reference genomes, gene sequences, PCR-based DNA markers, trait-linked DNA markers identified in genetic studies, SNPs, and in/dels on publicly available sequence read archives (SRAs). The data registered in Plant GARDEN as of March 2023 included 304 assembled genome sequences, 11,331,614 gene sequences, 419,132 DNA markers, 8,225 QTLs, and 5,934 SNP lists (gvcf files). In addition, we have re-annotated all the genes registered in Plant GARDEN by using a functional annotation tool, Hayai-Annotation, to compare the orthologous relationships among genes. CONCLUSION: The aim of Plant GARDEN is to provide plant genome information for use in the fields of plant science as well as for plant-based industries, education, and other relevant areas. Therefore, we have designed a WUI that allows a diverse range of users to access such information in an easy-to-understand manner. Plant GARDEN will eventually include a wide range of plant species for which genome sequences are assembled, and thus the number of plant species in the database will continue to expand. We anticipate that Plant GARDEN will promote the understanding of genomes and gene diversity by facilitating comparisons of the registered sequences.

Identification of mild cognitive impairment subtypes predicting conversion to Alzheimer's disease using multimodal data.

Mild cognitive impairment (MCI) is a high-risk condition for conversion to Alzheimer's disease (AD) dementia. However, individuals with MCI show heterogeneous patterns of pathology and conversion to AD dementia. Thus, detailed subtyping of MCI subjects and accurate prediction of the patients in whom MCI will convert to AD dementia is critical for identifying at-risk populations and the underlying biological features. To this end, we developed a model that simultaneously subtypes MCI subjects and predicts conversion to AD and performed an analysis of the underlying biological characteristics of each subtype. In particular, a heterogeneous mixture learning (HML) method was used to build a decision tree-based model based on multimodal data, including cerebrospinal fluid (CSF) biomarker data, structural magnetic resonance imaging (MRI) data, APOE genotype data, and age at examination. The HML model showed an average F1 score of 0.721, which was comparable to the random forest method and had significantly more predictive accuracy than the CART method. The HML-generated decision tree was also used to classify-five subtypes of MCI. Each MCI subtype was characterized in terms of the degree of abnormality in CSF biomarkers, brain atrophy, and cognitive decline. The five subtypes of MCI were further categorized into three groups: one subtype with low conversion rates (similar to cognitively normal subjects); three subtypes with moderate conversion rates; and one subtype with high conversion rates (similar to AD dementia patients). The subtypes with moderate conversion rates were subsequently separated into a group with CSF biomarker abnormalities and a group with brain atrophy. The subtypes identified in this study exhibited varying MCI-to-AD conversion rates and differing biological profiles.

A heterozygous LAMA5 variant may contribute to slowly progressive, vinculin-enhanced familial FSGS and pulmonary defects.

The LAMA5 gene encodes laminin α5, an indispensable component of glomerular basement membrane and other types of basement membrane. A homozygous pathological variant in LAMA5 is known to cause a systemic developmental syndrome including glomerulopathy. However, the roles of heterozygous LAMA5 gene variants in human renal and systemic diseases have remained unclear. We performed whole-exome sequencing analyses of a family with slowly progressive nephropathy associated with hereditary focal segmental glomerulosclerosis, and we identified what we believe to be a novel probable pathogenic variant of LAMA5, NP_005551.3:p.Val3687Met. In vitro analyses revealed cell type-dependent changes in secretion of variant laminin α5 laminin globular 4-5 (LG4-5) domain. Heterozygous and homozygous knockin mice with a corresponding variant of human LAMA5, p.Val3687Met, developed focal segmental glomerulosclerosis-like pathology with reduced laminin α5 and increased glomerular vinculin levels, which suggested that impaired cell adhesion may underlie this glomerulopathy. We also identified pulmonary defects such as bronchial deformity and alveolar dilation. Reexaminations of the family revealed phenotypes compatible with reduced laminin α5 and increased vinculin levels in affected tissues. Thus, the heterozygous p.Val3687Met variant may cause a new syndromic nephropathy with focal segmental glomerulosclerosis through possibly defective secretion of laminin α5. Enhanced vinculin may be a useful disease marker.

Construction of prediction models for growth traits of soybean cultivars based on phenotyping in diverse genotype and environment combinations.

As soybean cultivars are adapted to a relatively narrow range of latitude, the effects of climate changes are estimated to be severe. To address this issue, it is important to improve our understanding of the effects of climate change by applying the simulation model including both genetic and environmental factors with their interactions (G×E). To achieve this goal, we conducted the field experiments for soybean core collections using multiple sowing times in multi-latitudinal fields. Sowing time shifts altered the flowering time (FT) and growth phenotypes, and resulted in increasing the combinations of genotypes and environments. Genome-wide association studies for the obtained phenotypes revealed the effects of field and sowing time to the significance of detected alleles, indicating the presence of G×E. By using accumulated phenotypic and environmental data in 2018 and 2019, we constructed multiple regression models for FT and growth pattern. Applicability of the constructed models was evaluated by the field experiments in 2020 including a novel field, and high correlation between the predicted and measured values was observed, suggesting the robustness of the models. The models presented here would allow us to predict the phenotype of the core collections in a given environment.

Synergistic role of retinoic acid signaling and Gata3 during primitive choanae formation.

Developmental defects of primitive choanae, an anatomical path to connect the embryonic nasal and oral cavity, result in disorders called choanal atresia (CA), which are associated with many congenital diseases and require immediate clinical intervention after birth. Previous studies revealed that reduced retinoid signaling underlies the etiology of CA. In the present study, by using multiple mouse models which conditionally deleted Rdh10 and Gata3 during embryogenesis, we showed that Gata3 expression is regulated by retinoid signaling during embryonic craniofacial development and plays crucial roles for development of the primitive choanae. Interestingly, Gata3 loss of function is known to cause hypoparathyroidism, sensorineural deafness and renal disease (HDR) syndrome, which exhibits CA as one of the phenotypes in humans. Our model partially phenocopies HDR syndrome with CA, and is thus a useful tool for investigating the molecular and cellular mechanisms of HDR syndrome. We further uncovered critical synergy of Gata3 and retinoid signaling during embryonic development, which will shed light on novel molecular and cellular etiology of congenital defects in primitive choanae formation.

Long-term prognosis and genetic background of cardiomyopathy in 223 pediatric mitochondrial disease patients.

BACKGROUND: Cardiomyopathy is a risk factor for poor prognosis in pediatric patients with mitochondrial disease. However, other risk factors including genetic factors related to poor prognosis in mitochondrial disease has yet to be fully elucidated. METHODS AND RESULTS: Between January 2004 and September 2019, we enrolled 223 consecutive pediatric mitochondrial disease patients aged <18 years with a confirmed genetic diagnosis, including 114 with nuclear gene mutations, 89 patients with mitochondrial DNA (mtDNA) point mutations, 11 with mtDNA single large-scale deletions and 9 with chromosomal aberrations. Cardiomyopathy at baseline was observed in 46 patients (21%). Hazard ratios (HR) and 95% confidence intervals (CI) were calculated for all-cause mortality. Over a median follow-up of 36 months (12-77), there were 85 deaths (38%). The overall survival rate was significantly lower in patients with cardiomyopathy than in those without (p < 0.001, log-rank test). By multivariable analysis, left ventricular (LV) hypertrophy (HR = 4.6; 95% CI: 2.8-7.3), neonatal onset (HR = 2.9; 95% CI: 1.8-4.5) and chromosomal aberrations (HR = 2.9; 95% CI: 1.3-6.5) were independent predictors of all-cause mortality. Patients with LV hypertrophy with neonatal onset and/or chromosomal aberrations had higher mortality (100% in 21 patients) than those with LV hypertrophy alone (71% in 14 patients). CONCLUSION: In pediatric patients with mitochondrial disease, cardiomyopathy was common (21%) and was associated with increased mortality. LV hypertrophy, neonatal onset and chromosomal aberrations were independent predictors of all-cause mortality. Prognosis is particularly unfavorable if LV hypertrophy is combined with neonatal onset and/or chromosomal aberrations.

Genome-wide copy number variation analysis of hepatitis B infection in a Japanese population.

Genome-wide association studies have been performed to identify common genetic variants associated with hepatitis B (HB). However, little is known about copy number variations (CNVs) in HB. In this study, we performed a genome-wide CNV analysis between 1830 healthy controls and 1031 patients with HB infection after quality control. Using signal calling by the Axiom Analysis Suite and CNV detection by PennCNV software, we obtained a total of 4494 CNVs across all individuals. The genes with CNVs that were found only in the HB patients were associated with the immune system, such as antigen processing. A gene-level CNV association test revealed statistically significant CNVs in the contactin 6 (CNTN6) gene. Moreover, we also performed gene-level CNV association tests in disease subgroups, including hepatocellular carcinoma patients, liver cirrhosis patients, and HBV carriers, including asymptomatic carriers and patients with HBV-derived chronic hepatitis. Our findings from germline cells suggested that patient-specific CNVs may be inherent genetic risk factors for HB.

Upregulated expression of a subset of genes in APP;ob/ob mice: Evidence of an interaction between diabetes-linked obesity and Alzheimer's disease.

Clinical studies have indicated that obesity and diabetes are associated with Alzheimer's disease (AD) and neurodegeneration. However, the mechanism by which obesity/diabetes and AD interact with each other and contribute to dementia remains elusive. To obtain insights into their interaction at molecular levels, we performed gene expression analysis of APP;ob/ob mice, which were generated by crossing transgenic AD model mice (APP23 mice) with ob/ob mice, which are obese and mildly diabetic. The Aß level in these mice was reduced compared with that in pure APP mice. However, we identified a cluster of genes (cluster 10) upregulated in APP;ob/ob mice but not in either APP or ob/ob mice. Interestingly, genes upregulated in the human AD brain were enriched in cluster 10. Moreover, genes in cluster 10 formed a network and shared upregulated genes with a cell model of neurodegeneration and other models of neurological disorders such as ischemia and epilepsy. In silico analyses showed that serum response factor (SRF), recently identified in a single-cell analysis of human brains as a transcription factor that can control the conversion from healthy cells to AD cells, might be a common transcriptional regulator for a subset of cluster 10 genes. These data suggest that upregulation of genes uniquely associated with APP;ob/ob mice is an evidence of the interaction between obesity/diabetes and AD.

Cyclosporine A Treatment of Proteinuria in a New Case of MAFB-Associated Glomerulopathy without Extrarenal Involvement: A Case Report.

The MAFB gene encodes an important basic leucine zipper transcription factor that functions in glomerular podocytes, macrophages, and osteoclasts. Recently, MAFB was identified as the gene that was responsible for causing nephropathy with focal segmental glomerulosclerosis (FSGS) with multicentric carpotarsal osteolysis (MCTO) or Duane retraction syndrome (DRS). Here, we describe a patient with nephropathy associated with FSGS who exhibited a novel stop-gain variant in the MAFB gene (NM_005461:c.590C>A (p.Ser197Ter)). The patient's father exhibited proteinuria with FSGS with possible DRS, whereas the patient exhibited nephropathy with FSGS and nearly normal eye movement and hearing function, as well as intact bone structure in the extremities. Conventional oral steroids or immunosuppressive drugs have not demonstrated effectiveness for patients with nephropathy who exhibit pathogenic variants in MAFB, except for a patient with nephropathy with FSGS and MCTO who experienced attenuated proteinuria within the subnephrotic range in response to cyclosporine A (CyA) treatment for at least 4 years. Thus, we attempted administration of CyA in our patient. Unexpectedly, the patient demonstrated good and rapid responses to CyA, including a partial reduction in proteinuria from approximately 2.0 g/g Cr to proteinuria within the subnephrotic range (0.27 g/g Cr) after 13 months of observation. Our findings suggest that CyA may be a suitable treatment option for patients with nephropathy with FSGS who exhibit pathogenic MAFB variants.

Cooperation of LIM domain-binding 2 (LDB2) with EGR in the pathogenesis of schizophrenia.

Genomic defects with large effect size can help elucidate unknown pathologic architecture of mental disorders. We previously reported on a patient with schizophrenia and a balanced translocation between chromosomes 4 and 13 and found that the breakpoint within chromosome 4 is located near the LDB2 gene. We show here that Ldb2 knockout (KO) mice displayed multiple deficits relevant to mental disorders. In particular, Ldb2 KO mice exhibited deficits in the fear-conditioning paradigm. Analysis of the amygdala suggested that dysregulation of synaptic activities controlled by the immediate early gene Arc is involved in the phenotypes. We show that LDB2 forms protein complexes with known transcription factors. Consistently, ChIP-seq analyses indicated that LDB2 binds to > 10,000 genomic sites in human neurospheres. We found that many of those sites, including the promoter region of ARC, are occupied by EGR transcription factors. Our previous study showed an association of the EGR family genes with schizophrenia. Collectively, the findings suggest that dysregulation in the gene expression controlled by the LDB2-EGR axis underlies a pathogenesis of subset of mental disorders.

Lipid Pathology of the Corpus Callosum in Schizophrenia and the Potential Role of Abnormal Gene Regulatory Networks with Reduced Microglial Marker Expression.

Structural changes in the corpus callosum have been reported in schizophrenia; however, the underlying molecular mechanism remains unclear. As the corpus callosum is high in lipid content, we analyzed the lipid contents of the corpora callosa from 15 patients with schizophrenia and 15 age- and sex-matched controls using liquid chromatography coupled to tandem mass spectrometry and identified lipid combinations associated with schizophrenia. Real-time quantitative polymerase chain reaction analyses using extended samples (schizophrenia, n = 95; control, n = 91) showed low expression levels of lipid metabolism-related genes and their potential upstream transcription factors in schizophrenia. Subsequent pathway analysis identified a gene regulatory network where nuclear factor of activated T cells 2 (NFATC2) is placed most upstream. We also observed low gene expression levels of microglial markers, inflammatory cytokines, and colony-stimulating factor 1 receptor (CSF1R), which is known to regulate the density of microglia, in the corpus callosum in schizophrenia. The interactions between CSF1R and several genes in the presently identified gene network originating from NFATC2 have been reported. Collectively, this study provides evidence regarding lipid abnormalities in the corpora callosa of patients with schizophrenia and proposes the potential role of impaired "NFATC2-relevant gene network-microglial axis" as its underlying mechanism.

Disruption of a RAC1-centred network is associated with Alzheimer's disease pathology and causes age-dependent neurodegeneration.

The molecular biological mechanisms of Alzheimer's disease (AD) involve disease-associated crosstalk through many genes and include a loss of normal as well as a gain of abnormal interactions among genes. A protein domain network (PDN) is a collection of physical bindings that occur between protein domains, and the states of the PDNs in patients with AD are likely to be perturbed compared to those in normal healthy individuals. To identify PDN changes that cause neurodegeneration, we analysed the PDNs that occur among genes co-expressed in each of three brain regions at each stage of AD. Our analysis revealed that the PDNs collapsed with the progression of AD stage and identified five hub genes, including Rac1, as key players in PDN collapse. Using publicly available as well as our own gene expression data, we confirmed that the mRNA expression level of the RAC1 gene was downregulated in the entorhinal cortex (EC) of AD brains. To test the causality of these changes in neurodegeneration, we utilized Drosophila as a genetic model and found that modest knockdown of Rac1 in neurons was sufficient to cause age-dependent behavioural deficits and neurodegeneration. Finally, we identified a microRNA, hsa-miR-101-3p, as a potential regulator of RAC1 in AD brains. As the Braak neurofibrillary tangle (NFT) stage progressed, the expression levels of hsa-miR-101-3p were increased specifically in the EC. Furthermore, overexpression of hsa-miR-101-3p in the human neuronal cell line SH-SY5Y caused RAC1 downregulation. These results highlight the utility of our integrated network approach for identifying causal changes leading to neurodegeneration in AD.

Association of Basophil-Expressing Genes with Effectiveness of Sublingual Immunotherapy.

Basophils were reported to be associated with allergy pathogenesis and the efficacy of allergen immunotherapy. Using a purified cedar allergen, we recently studied the effectiveness of sublingual immunotherapy for patients with Japanese cedar pollinosis. Patients were classified as high responders (HR) and nonresponders (NR), and comprehensive microarray analysis was used to examine peripheral basophils in both groups. A total of 153 genes were differentially expressed in HR and NR patients. Most of these differentially expressed genes encoded intracellular molecules, and expression levels were higher in HR patients than in NR patients. mRNA expression of the gene encoding D4, zinc, and double plant homeodomain (PHD) fingers family 2 (DPF2) was significantly correlated with copy number variation (CNV). Genetic variation in the DPF2 gene and its expression in basophils might be associated with the efficacy of sublingual immunotherapy.

[Apolipoprotein E4, a Genetic Risk Factor for Alzheimer's Disease].

Apolipoprotein E (APOE) is reported to be a strong genetic risk factor for Alzheimer's disease (AD), broadly contributing to the AD pathologies observed in most populations. However, it is difficult to explicate these AD pathologies based only on the known functions of APOE. In this review article, we revisited the histories and functions of APOE and also reviewed its recently elucidated the pleiotropic roles in the brain.

Perturbed development of cranial neural crest cells in association with reduced sonic hedgehog signaling underlies the pathogenesis of retinoic-acid-induced cleft palate.

Cleft palate (CP) is one of the most common congenital craniofacial anomalies in humans and can be caused by either single or multiple genetic and environmental factor(s). With respect to environmental factors, excessive intake of vitamin A during early pregnancy is associated with increased incidence of CP in offspring both in humans and in animal models. Vitamin A is metabolized to retinoic acid (RA); however, the pathogenetic mechanism of CP caused by altered RA signaling during early embryogenesis is not fully understood. To investigate the detailed cellular and molecular mechanism of RA-induced CP, we administered all-trans RA to pregnant mice at embryonic day (E)8.5. In the RA-treated group, we observed altered expression of Sox10, which marks cranial neural crest cells (CNCCs). Disruption of Sox10 expression was also observed at E10.5 in the maxillary component of the first branchial arch, which gives rise to secondary palatal shelves. Moreover, we found significant elevation of CNCC apoptosis in RA-treated embryos. RNA-sequencing comparisons of RA-treated embryos compared to controls revealed alterations in Sonic hedgehog (Shh) signaling. More specifically, the expression of Shh and its downstream genes Ptch1 and Gli1 was spatiotemporally downregulated in the developing face of RA-treated embryos. Consistent with these findings, the incidence of CP in association with excessive RA signaling was reduced by administration of the Shh signaling agonist SAG (Smoothened agonist). Altogether, our results uncovered a novel mechanistic association between RA-induced CP with decreased Shh signaling and elevated CNCC apoptosis.

Enhancer variants associated with Alzheimer's disease affect gene expression via chromatin looping.

BACKGROUND: Genome-wide association studies (GWASs) have identified single-nucleotide polymorphisms (SNPs) that may be genetic factors underlying Alzheimer's disease (AD). However, how these AD-associated SNPs (AD SNPs) contribute to the pathogenesis of this disease is poorly understood because most of them are located in non-coding regions, such as introns and intergenic regions. Previous studies reported that some disease-associated SNPs affect regulatory elements including enhancers. We hypothesized that non-coding AD SNPs are located in enhancers and affect gene expression levels via chromatin loops. METHODS: To characterize AD SNPs within non-coding regions, we extracted 406 AD SNPs with GWAS p-values of less than 1.00 × 10- 6 from the GWAS catalog database. Of these, we selected 392 SNPs within non-coding regions. Next, we checked whether those non-coding AD SNPs were located in enhancers that typically regulate gene expression levels using publicly available data for enhancers that were predicted in 127 human tissues or cell types. We sought expression quantitative trait locus (eQTL) genes affected by non-coding AD SNPs within enhancers because enhancers are regulatory elements that influence the gene expression levels. To elucidate how the non-coding AD SNPs within enhancers affect the gene expression levels, we identified chromatin-chromatin interactions by Hi-C experiments. RESULTS: We report the following findings: (1) nearly 30% of non-coding AD SNPs are located in enhancers; (2) eQTL genes affected by non-coding AD SNPs within enhancers are associated with amyloid beta clearance, synaptic transmission, and immune responses; (3) 95% of the AD SNPs located in enhancers co-localize with their eQTL genes in topologically associating domains suggesting that regulation may occur through chromatin higher-order structures; (4) rs1476679 spatially contacts the promoters of eQTL genes via CTCF-CTCF interactions; (5) the effect of other AD SNPs such as rs7364180 is likely to be, at least in part, indirect through regulation of transcription factors that in turn regulate AD associated genes. CONCLUSION: Our results suggest that non-coding AD SNPs may affect the function of enhancers thereby influencing the expression levels of surrounding or distant genes via chromatin loops. This result may explain how some non-coding AD SNPs contribute to AD pathogenesis.

[Mechanisms of allergen immunotherapy elucidated through integrated comparative analysis].

From the era of subcutaneous immunotherapy (SCIT) in 1960s, allergen immunotherapy (AIT) has been established as a highly effective and curable treatment for allergic diseases. Furthermore, the recent appearance of sublingual immunotherapy (SLIT) in which the complicated administration procedure in SCIT was improved has been causing paradigm shifts in the treatment of allergic rhinitis. During the long history of AIT, the mechanisms by which this therapy leads its strong efficacy have been investigated but not fully clarified yet. The production of blocking antibodies that interrupt allergen-IgE binding, normalization of Th1/Th2 balance, and introduction of regulatory T cells are the major candidate mechanisms, though there are several conflicting reports. In our recent clinical study of SLIT against Japanese cedar pollinosis, we also tried to elucidate its mechanisms. Especially by comparing high-responder and non-responder patients using integrated analysis with multiple data, not by comparing with a placebo control group using individual data, we have successfully identified several target molecules and cascades of SLIT. Herein, we would like to describe the potential mechanisms by which AIT exhibits its strong efficacy with referring our recent novel findings.

Cardiomyopathy in children with mitochondrial disease: Prognosis and genetic background.

BACKGROUND: Cardiomyopathy is a reported indicator of poor prognosis in children with mitochondrial disease. However, the association between prognosis and the genetic background of cardiomyopathy in children with mitochondrial disease has yet to be fully elucidated. METHODS AND RESULTS: Of 137 children with mitochondrial disease whose genetic diagnosis was made between 2004 and 2018, 29 had mitochondrial cardiomyopathy (21%). After a median follow-up of 35 months, the overall survival rate was significantly lower in patients with cardiomyopathy than in those without (p < 0.001). Ten-year Kaplan-Meier estimates of overall survival were 18 and 67%, respectively. Among the 21 cardiomyopathy patients who died, two died within one month of birth (COQ4 in one patient, and COX10 in one patient), ten died within one year (BOLA3 in three patients, QRSL1 in two patients, large chromosomal deletions in two patients, MT-ATP6/8 in one patient, MT-TL1 in one patient, and TAZ gene in one patient), and nine died after one year (MT-ND5 in three patients, MT-TL1 in three patients, ACAD9 in one patient, KARS in one patient, and MT-TV in one patient). In the three patients with mitochondrial DNA mutations whose cardiac tissues were available, high heteroplasmy rates in the cardiac tissue were observed for m.8528T>C (90%, died at 2 months of age) and m.3243A>G (90 and 80%, died at 12 and 13 years of age, respectively). CONCLUSIONS: In children with mitochondrial disease, cardiomyopathy was common (21%) and was associated with increased mortality. Genetic analysis coupled with detailed phenotyping could be useful for prognosis.