ABSTRACT
PURPOSE: To identify therapies for combined D, L-2-hydroxyglutaric aciduria (C-2HGA), a rare genetic disorder caused by recessive variants in the SLC25A1 gene. METHODS: Patients C-2HGA were identified and diagnosed by whole exome sequencing and biochemical genetic testing. Patient derived fibroblasts were then treated with phenylbutyrate and the functional effects assessed by metabolomics and RNA-sequencing. RESULTS: In this study, we demonstrated that C-2HGA patient derived fibroblasts exhibited impaired cellular bioenergetics. Moreover, Fibroblasts form one patient exhibited worsened cellular bioenergetics when supplemented with citrate. We hypothesized that treating patient cells with phenylbutyrate (PB), an FDA approved pharmaceutical drug that conjugates glutamine for renal excretion, would reduce mitochondrial 2-ketoglutarate, thereby leading to improved cellular bioenergetics. Metabolomic and RNA-seq analyses of PB-treated fibroblasts demonstrated a significant decrease in intracellular 2-ketoglutarate, 2-hydroxyglutarate, and in levels of mRNA coding for citrate synthase and isocitrate dehydrogenase. Consistent with the known action of PB, an increased level of phenylacetylglutamine in patient cells was consistent with the drug acting as 2-ketoglutarate sink. CONCLUSION: Our pre-clinical studies suggest that citrate supplementation has the possibility exacerbating energy metabolism in this condition. However, improvement in cellular bioenergetics suggests phenylbutyrate might have interventional utility for this rare disease.
Subject(s)
Fibroblasts , Glutarates , Phenylbutyrates , Humans , Phenylbutyrates/pharmacology , Phenylbutyrates/therapeutic use , Fibroblasts/metabolism , Fibroblasts/drug effects , Glutarates/metabolism , Ketoglutaric Acids/metabolism , Energy Metabolism/drug effects , Energy Metabolism/genetics , Mitochondria/drug effects , Mitochondria/metabolism , Mitochondria/genetics , Metabolomics , Exome Sequencing , Citrate (si)-Synthase/metabolism , Citrate (si)-Synthase/genetics , Brain Diseases, Metabolic, Inborn/drug therapy , Brain Diseases, Metabolic, Inborn/genetics , Brain Diseases, Metabolic, Inborn/metabolism , Isocitrate Dehydrogenase/genetics , Isocitrate Dehydrogenase/metabolism , Brain Diseases, Metabolic/drug therapy , Brain Diseases, Metabolic/genetics , Brain Diseases, Metabolic/metabolism , Brain Diseases, Metabolic/pathology , Multiomics , Mitochondrial Proteins , Organic Anion TransportersABSTRACT
BACKGROUND: It is critical to understand the wide-ranging clinical and non-clinical effects of genome sequencing (GS) for parents in the NICU context. We assessed parents' experiences with GS as a first-line diagnostic tool for infants with suspected genetic conditions in the NICU. METHODS: Parents of newborns (N = 62) suspected of having a genetic condition were recruited across five hospitals in the southeast United States as part of the SouthSeq study. Semi-structured interviews (N = 78) were conducted after parents received their child's sequencing result (positive, negative, or variants of unknown significance). Thematic analysis was performed on all interviews. RESULTS: Key themes included that (1) GS in infancy is important for reproductive decision making, preparing for the child's future care, ending the diagnostic odyssey, and sharing results with care providers; (2) the timing of disclosure was acceptable for most parents, although many reported the NICU environment was overwhelming; and (3) parents deny that receiving GS results during infancy exacerbated parent-infant bonding, and reported variable impact on their feelings of guilt. CONCLUSION: Parents reported that GS during the neonatal period was useful because it provided a "backbone" for their child's care. Parents did not consistently endorse negative impacts like interference with parent-infant bonding.
ABSTRACT
Combined D, L-2-Hydroxyglutaric Aciduria (D,L-2HGA) is a rare genetic disorder caused by recessive mutations in the SLC25A1 gene that encodes the mitochondrial citrate carrier protein (CIC). SLC25A1 deficiency leads to a secondary increase in mitochondrial 2-ketoglutarate that, in turn, is reduced to neurotoxic 2-hydroxyglutarate. Clinical symptoms of Combined D,L-2HGA include neonatal encephalopathy, respiratory insufficiency and often with death in infancy. No current therapies exist, although replenishing cytosolic stores by citrate supplementation to replenish cytosolic stores has been proposed. In this study, we demonstrated that patient derived fibroblasts exhibited impaired cellular bioenergetics that were worsened with citrate supplementation. We hypothesized treating patient cells with phenylbutyrate, an FDA approved pharmaceutical drug, would reduce mitochondrial 2-ketoglutarate, leading to improved cellular bioenergetics including oxygen consumption and fatty acid oxidation. Metabolomic and RNA-seq analyses demonstrated a significant decrease in intracellular 2-ketoglutarate, 2-hydroxyglutarate, and in levels of mRNA coding for citrate synthase and isocitrate dehydrogenase. Consistent with the known action of phenylbutyrate, detected levels of phenylacetylglutamine was consistent with the drug acting as 2-ketoglutarate sink in patient cells. Our pre-clinical studies suggest citrate supplementation is unlikely to be an effective treatment of the disorder. However, cellular bioenergetics suggests phenylbutyrate may have interventional utility for this rare disease.
ABSTRACT
BACKGROUND: The uptake of exome/genome sequencing has introduced unexpected testing results (incidental findings) that have become a major challenge for both testing laboratories and providers. While the American College of Medical Genetics and Genomics has outlined guidelines for laboratory management of clinically actionable secondary findings, debate remains as to whether incidental findings should be returned to patients, especially those representing pediatric populations. METHODS: The Sequencing Analysis and Diagnostic Yield working group in the Clinical Sequencing Evidence-Generating Research Consortium has collected a cohort of pediatric patients found to harbor a genomic sequencing-identified non-ACMG-recommended incidental finding. The incidental variants were not thought to be associated with the indication for testing and were disclosed to patients and families. RESULTS: In total, 23 "non-ACMG-recommended incidental findings were identified in 21 pediatric patients included in the study. These findings span four different research studies/laboratories and demonstrate differences in incidental finding return rate across study sites. We summarize specific cases to highlight core considerations that surround identification and return of incidental findings (uncertainty of disease onset, disease severity, age of onset, clinical actionability, and personal utility), and suggest that interpretation of incidental findings in pediatric patients can be difficult given evolving phenotypes. Furthermore, return of incidental findings can benefit patients and providers, but do present challenges. CONCLUSIONS: While there may be considerable benefit to return of incidental genetic findings, these findings can be burdensome to providers and present risk to patients. It is important that laboratories conducting genomic testing establish internal guidelines in anticipation of detection. Moreover, cross-laboratory guidelines may aid in reducing the potential for policy heterogeneity across laboratories as it relates to incidental finding detection and return. However, future discussion is required to determine whether cohesive guidelines or policy statements are warranted.
Subject(s)
Exome , Genome, Human , Humans , United States , Chromosome Mapping , Base Sequence , GenomicsABSTRACT
Bi-allelic variants in Iron-Sulfur Cluster Scaffold (NFU1) have previously been associated with multiple mitochondrial dysfunctions syndrome 1 (MMDS1) characterized by early-onset rapidly fatal leukoencephalopathy. We report 19 affected individuals from 10 independent families with ultra-rare bi-allelic NFU1 missense variants associated with a spectrum of early-onset pure to complex hereditary spastic paraplegia (HSP) phenotype with a longer survival (16/19) on one end and neurodevelopmental delay with severe hypotonia (3/19) on the other. Reversible or irreversible neurological decompensation after a febrile illness was common in the cohort, and there were invariable white matter abnormalities on neuroimaging. The study suggests that MMDS1 and HSP could be the two ends of the NFU1-related phenotypic continuum.
Subject(s)
Spastic Paraplegia, Hereditary , Humans , Phenotype , Spastic Paraplegia, Hereditary/genetics , Mutation, Missense , Alleles , Iron/metabolism , Carrier Proteins/geneticsABSTRACT
BACKGROUND: Mitochondrial toxicity resulting in myopathy and lactic acidosis has been described in antiretroviral (ARV)-exposed patients. We hypothesized that myopathy in HIV-infected, ARV-treated children would be associated with metabolic (acylcarnitines) and genetic (variants in metabolic genes) markers of dysfunctional fatty acid oxidation (FAO). METHODS: Acylcarnitine profiles (ACP) were analyzed for 74 HIV-infected children on nucleoside reverse transcriptase inhibitor (NRTI)-containing ARV. Thirty-seven participants with ≥2 creatine kinase measurements >500 IU (n = 18) or evidence of echocardiographic cardiomyopathy (n = 19) were matched with 37 participants without myopathy. Single nucleotide polymorphisms (SNPs) in FAO genes were also evaluated. RESULTS: Abnormal ACP was 73% (95% CI: 56%-86%) and 62% (95% CI: 45%-78%) in the myopathic and nonmyopathic groups, respectively. No significant association was found between myopathy and having an abnormal ACP (OR = 2.10, P = 0.22). In univariate analysis, a 1-year increase in NRTI use was associated with a 20% increase in odds of at least 1 ACP abnormality [OR (95% CI) = 1.20 (1.03-1.41); P = 0.02), and a 1-year increase in protease inhibitor use was associated with 28% increase in the odds of having at least 1 ACP abnormality [OR (95% CI) = 1.28 (1.07-1.52); P = 0.006). Three SNPs, all in the gene for the carnitine transporter ( SLC22A5 ), were associated with the cardiomyopathy phenotype. CONCLUSION: FAO appears to be altered in HIV-infected children with and without myopathy, but abnormal FAO does not fully explain myopathy in ARV-exposed children. Further study of SLC22A5 variation in ARV-exposed people is warranted carnitine transporter dysfunction-related cardiomyopathy may be treatable.
Subject(s)
Anti-HIV Agents , HIV Infections , Muscular Diseases , Anti-HIV Agents/therapeutic use , Anti-Retroviral Agents/therapeutic use , Carnitine/analogs & derivatives , Carnitine/therapeutic use , Child , Genetic Variation , HIV Infections/complications , HIV Infections/drug therapy , Humans , Muscular Diseases/chemically induced , Muscular Diseases/drug therapy , Muscular Diseases/genetics , Oxidation-Reduction , Reverse Transcriptase Inhibitors/therapeutic use , Solute Carrier Family 22 Member 5/geneticsABSTRACT
The hereditary ataxias are a heterogenous group of disorders with an increasing number of causative genes being described. Due to the clinical and genetic heterogeneity seen in these conditions, the majority of such individuals endure a diagnostic odyssey or remain undiagnosed. Defining the molecular etiology can bring insights into the responsible molecular pathways and eventually the identification of therapeutic targets. Here, we describe the identification of biallelic variants in the GEMIN5 gene among seven unrelated families with nine affected individuals presenting with spastic ataxia and cerebellar atrophy. GEMIN5, an RNA-binding protein, has been shown to regulate transcription and translation machinery. GEMIN5 is a component of small nuclear ribonucleoprotein (snRNP) complexes and helps in the assembly of the spliceosome complexes. We found that biallelic GEMIN5 variants cause structural abnormalities in the encoded protein and reduce expression of snRNP complex proteins in patient cells compared with unaffected controls. Finally, knocking out endogenous Gemin5 in mice caused early embryonic lethality, suggesting that Gemin5 expression is crucial for normal development. Our work further expands on the phenotypic spectrum associated with GEMIN5-related disease and implicates the role of GEMIN5 among patients with spastic ataxia, cerebellar atrophy, and motor predominant developmental delay.
ABSTRACT
Individuals with LPIN1 deficiency have early recurrent, life-threatening rhabdomyolysis but the full phenotypic spectrum and optimal treatment of the disorder remains unknown. Here we report the clinical details and treatment outcomes of 6 patients from our health system. The average age of presentation in our cohort was 23.8 months ±11.6 months (range 15-46 months). The average number of days for each hospitalization for this cohort is 11.7±13.2 days. Creatinine kinase (CK) levels peak during our care averaged 607,725 units/L (range 157,000-1,100,000 units/L). We observed that aspartate aminotransferase levels paralleled the CK levels in its elevation and resolution (Pearson's correlation R = 0.995); while alanine aminotransferase paralleled the elevation but lagged in the resolution of CK levels (R = 0.728). Unlike historical accounts, in our patient population, rhabdomyolysis was sometimes seen without inciting viral or traumatic events. We also cared for multiple individuals that had received treatment at other centers. This allowed us to compare multiple practice approaches and led to a standardized Care Recommendations.
ABSTRACT
PURPOSE: SouthSeq is a translational research study that undertook genome sequencing (GS) for infants with symptoms suggestive of a genetic disorder. Recruitment targeted racial/ethnic minorities and rural, medically underserved areas in the Southeastern United States, which are historically underrepresented in genomic medicine research. METHODS: GS and analysis were performed for 367 infants to detect disease-causal variation concurrent with standard of care evaluation and testing. RESULTS: Definitive diagnostic (DD) or likely diagnostic (LD) genetic findings were identified in 30% of infants, and 14% of infants harbored an uncertain result. Only 43% of DD/LD findings were identified via concurrent clinical genetic testing, suggesting that GS testing is better for obtaining early genetic diagnosis. We also identified phenotypes that correlate with the likelihood of receiving a DD/LD finding, such as craniofacial, ophthalmologic, auditory, skin, and hair abnormalities. We did not observe any differences in diagnostic rates between racial/ethnic groups. CONCLUSION: We describe one of the largest-to-date GS cohorts of ill infants, enriched for African American and rural patients. Our results show the utility of GS because it provides early-in-life detection of clinically relevant genetic variations not detected by current clinical genetic testing, particularly for infants exhibiting certain phenotypic features.
Subject(s)
Diagnostic Tests, Routine , Genetic Testing , Base Sequence , Chromosome Mapping , Genetic Testing/methods , Genomics , HumansABSTRACT
BACKGROUND: Many infants in the neonatal intensive care unit (NICU) have genetic disorders or birth defects. The demand for genetic services is often complicated by a shortage of genetic providers. PROBLEM: Our hospital experienced a significant reduction in genetic workforce, leading to insufficient genetic services to meet demand. METHODS: The Plan-Do-Study-Act method of quality improvement was used to assess available resources, select an intervention plan, and collect patient outcome and provider satisfaction data. INTERVENTION: An asynchronous telehealth model was deployed for clinical genetics consultations in our NICU utilizing a remote clinical geneticist. RESULTS: The pilot study included 111 asynchronous telehealth consultations; 21% received a genetic diagnosis before discharge. Diagnoses were primarily chromosomal and single gene disorders. Referring NICU providers reported high satisfaction. CONCLUSION: Asynchronous telehealth for clinical genetics is a feasible and successful alternative to an on-site clinical geneticist and should be considered in areas with a genetic workforce shortage.
Subject(s)
Intensive Care Units, Neonatal , Telemedicine , Humans , Infant , Infant, Newborn , Patient Discharge , Pilot Projects , Referral and ConsultationABSTRACT
It is unknown whether antiretroviral (ARV) drugs in women living with HIV (WLHIV) are associated with mitochondrial toxicity and altered fat oxidation and branched-chain amino acid metabolism in the placenta and fetus. Immediately after delivery, we froze placental biopsies from 20 WLHIV and 20 matched uninfected women. We analyzed global biochemical profiles using high-performance liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry. We used t-tests, principle component analysis, hierarchical clustering, and random forest analysis (RFA) in our analysis. Twelve WLHIV were on protease inhibitors, six on non-nucleoside reverse inhibitors, and two on integrase strand inhibitors with optimized backbone. Mean birth weight of HIV-exposed neonates was significantly lower than unexposed neonates (3,075 g vs. 3,498 g, p = .01) at similar gestational age. RFA identified 30 of 702 analytes that differentiated the placental profiles of WLHIV from uninfected women with 72.5% predictive accuracy. Placental profiles of non-nucleoside reverse transcriptase inhibitor (NNRTI)-treated WLHIV exhibited lower levels of amino acids, including essential and branched-chain amino acids, and some medium-chain acylcarnitines. Placental metabolism may be altered in WLHIV, possibly associated with ARV exposure. The lower birth weight among neonates of WLHIV suggests the need for further studies considering potential deleterious effects of altered placenta metabolism on fetal growth and development.
Subject(s)
Anti-HIV Agents , HIV Infections , Anti-HIV Agents/adverse effects , Anti-HIV Agents/metabolism , Anti-Retroviral Agents/therapeutic use , Female , HIV Infections/drug therapy , HIV Infections/metabolism , Humans , Infant, Newborn , Metabolomics , Placenta/metabolism , PregnancyABSTRACT
BACKGROUND: Early-life metabolic derangements in HIV-exposed uninfected (HEU) infants have been reported. METHODS: Pregnant women with HIV and HIV-uninfected pregnant women were enrolled with their newborns in a US cohort from 2011 to 2015. We measured cord insulin, C-peptide, and metabolic cytokines of HEU and HIV-unexposed uninfected (HUU) newborns using ELISA and metabolites, lipid subspecies, and eicosanoids via liquid chromatography/mass spectrometry. Linear regression was employed to assess the association of intrauterine HIV/ART with insulin and C-peptide. Graphical lasso regression was used to identify differences between metabolite/lipid subspecies networks associated with C-peptide. RESULTS: Of 118 infants, 56 were HEU, ART exposed. In adjusted analyses, mean cord insulin (ß = 0.295, p = 0.03) and C-peptide (ß = 0.522, p < 0.01) were significantly higher in HEU vs. HUU newborns. HEU neonates exhibited primarily positive associations between complex lipids and C-peptide, indicative of fuel storage, and augmented associations between cord eicosanoids and cytokines. HUU neonates exhibited negative associations with lipids and C-peptide indicative of increased fuel utilization. CONCLUSION: Higher cord insulin and C-peptide in HEU vs. HUU newborns as well as differences in cord metabolites, metabolic-related cytokines, and eicosanoids may reflect a propensity for fuel storage and an inflammatory milieu suggestive of fetal metabolic changes associated with in utero HIV/ART exposure. IMPACT: There is a paucity of studies assessing cord blood and neonatal metabolic health in HIV-exposed uninfected (HEU) newborns, an increasing population worldwide. Compared to HIV-unexposed uninfected (HUU) newborns, HEU newborns exhibit alterations in fuel homeostasis and an inflammatory milieu associated with in utero HIV/antiretroviral therapy (ART) exposure. The long-term implications of these neonatal findings are as yet unknown, but merit continued evaluation as this important and growing population ages into adulthood.
Subject(s)
HIV Infections , Pregnancy Complications, Infectious , Adipokines , Adult , Anti-Retroviral Agents/therapeutic use , C-Peptide , Cytokines , Female , Fetal Blood , HIV Infections/complications , HIV Infections/drug therapy , Humans , Infant , Infant, Newborn , Lipidomics , Lipids , PregnancyABSTRACT
BACKGROUND: In persons living with HIV, mitochondrial disease (MD) is difficult to diagnose, as clinical signs are non-specific with inconsistent patterns. Fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15) are mitokines elevated in MD patients without HIV, and associated with cardiometabolic comorbidities in adults living with HIV. We assessed relationships of these biomarkers with MD in children living with perinatally-acquired HIV infection (CPHIV). SETTING: Cross-sectional study of CPHIV from Pediatric ACTG 219/219C classified by Mitochondrial Disease Criteria (MDC) that defines scores 2-4 as "possible" MD. METHODS: Each case with MDC equaling 4 (MDC4; n = 23) was matched to one randomly selected control displaying no MDC (MDC0; n = 23) based on calendar date. Unmatched cases with MDC equaling 3 (MDC3; n = 71) were also assessed. Plasma samples proximal to diagnoses were assayed by ELISA. Mitokine distributions were compared using Wilcoxon tests, Spearman correlations were calculated, and associations with MD status were assessed by conditional logistic regression. RESULTS: Median FGF21 and GDF15 concentrations, respectively, were highest in MDC4 (143.9 and 1441.1 pg/mL), then MDC3 (104.0 and 726.5 pg/mL), and lowest in controls (89.4 and 484.7 pg/mL). Distributions of FGF21 (paired Wilcoxon rank sum p = 0.002) and GDF15 (paired Wilcoxon rank sum p<0.001) differed in MDC4 vs MDC0. Mitokine concentrations were correlated across all participants (r = 0.33; p<0.001). Unadjusted odds ratios of being MDC4 vs MDC0 were 5.2 [95% confidence interval (CI): 1.06-25.92] for FGF21 and 3.5 (95%CI: 1.19-10.25) for GDF15. Relationships persisted after covariate adjustments. CONCLUSION: FGF21 and GDF15 levels may be useful biomarkers to screen for CPHIV with mitochondrial dysfunction.
Subject(s)
Fibroblast Growth Factors/biosynthesis , Growth Differentiation Factor 15/biosynthesis , HIV Infections/etiology , Mitochondrial Diseases/diagnosis , Adolescent , Anti-Retroviral Agents/adverse effects , Anti-Retroviral Agents/therapeutic use , Biomarkers/metabolism , Child , Child, Preschool , Cross-Sectional Studies , Cytokines/metabolism , Enzyme-Linked Immunosorbent Assay , Female , Fibroblast Growth Factors/genetics , Follow-Up Studies , Growth Differentiation Factor 15/genetics , HIV Infections/complications , HIV Infections/metabolism , Humans , Infant , Male , Mitochondria/metabolism , Mitochondrial Diseases/complications , Mitochondrial Diseases/metabolism , Regression Analysis , Risk , Young AdultABSTRACT
Surveillance for soil-transmitted helminths, strongyloidiasis, cryptosporidiosis, and giardiasis was conducted in Mississippi, USA. PCR performed on 224 fecal samples for all soil-transmitted helminths and on 370 samples for only Necator americanus and Strongyloides stercoralis identified 1 S. stercoralis infection. Seroprevalences were 8.8% for Toxocara, 27.4% for Cryptosporidium, 5.7% for Giardia, and 0.2% for Strongyloides parasites.
Subject(s)
Cryptosporidiosis , Cryptosporidium , Giardiasis , Parasitic Diseases , Feces , Humans , Mississippi/epidemiologyABSTRACT
Transportin-2 (TNPO2) mediates multiple pathways including non-classical nucleocytoplasmic shuttling of >60 cargoes, such as developmental and neuronal proteins. We identified 15 individuals carrying de novo coding variants in TNPO2 who presented with global developmental delay (GDD), dysmorphic features, ophthalmologic abnormalities, and neurological features. To assess the nature of these variants, functional studies were performed in Drosophila. We found that fly dTnpo (orthologous to TNPO2) is expressed in a subset of neurons. dTnpo is critical for neuronal maintenance and function as downregulating dTnpo in mature neurons using RNAi disrupts neuronal activity and survival. Altering the activity and expression of dTnpo using mutant alleles or RNAi causes developmental defects, including eye and wing deformities and lethality. These effects are dosage dependent as more severe phenotypes are associated with stronger dTnpo loss. Interestingly, similar phenotypes are observed with dTnpo upregulation and ectopic expression of TNPO2, showing that loss and gain of Transportin activity causes developmental defects. Further, proband-associated variants can cause more or less severe developmental abnormalities compared to wild-type TNPO2 when ectopically expressed. The impact of the variants tested seems to correlate with their position within the protein. Specifically, those that fall within the RAN binding domain cause more severe toxicity and those in the acidic loop are less toxic. Variants within the cargo binding domain show tissue-dependent effects. In summary, dTnpo is an essential gene in flies during development and in neurons. Further, proband-associated de novo variants within TNPO2 disrupt the function of the encoded protein. Hence, TNPO2 variants are causative for neurodevelopmental abnormalities.
Subject(s)
Developmental Disabilities/genetics , Drosophila Proteins/genetics , Eye Diseases, Hereditary/genetics , Intellectual Disability/genetics , Karyopherins/genetics , Musculoskeletal Abnormalities/genetics , beta Karyopherins/genetics , ran GTP-Binding Protein/genetics , Alleles , Amino Acid Sequence , Animals , Developmental Disabilities/metabolism , Developmental Disabilities/pathology , Drosophila Proteins/antagonists & inhibitors , Drosophila Proteins/metabolism , Drosophila melanogaster/genetics , Drosophila melanogaster/growth & development , Drosophila melanogaster/metabolism , Eye Diseases, Hereditary/metabolism , Eye Diseases, Hereditary/pathology , Female , Gene Dosage , Gene Expression Regulation, Developmental , Genome, Human , Humans , Infant , Infant, Newborn , Intellectual Disability/metabolism , Intellectual Disability/pathology , Karyopherins/antagonists & inhibitors , Karyopherins/metabolism , Male , Musculoskeletal Abnormalities/metabolism , Musculoskeletal Abnormalities/pathology , Mutation , Neurons/metabolism , Neurons/pathology , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Whole Genome Sequencing , beta Karyopherins/metabolism , ran GTP-Binding Protein/metabolismABSTRACT
GEMIN5, an RNA-binding protein is essential for assembly of the survival motor neuron (SMN) protein complex and facilitates the formation of small nuclear ribonucleoproteins (snRNPs), the building blocks of spliceosomes. Here, we have identified 30 affected individuals from 22 unrelated families presenting with developmental delay, hypotonia, and cerebellar ataxia harboring biallelic variants in the GEMIN5 gene. Mutations in GEMIN5 perturb the subcellular distribution, stability, and expression of GEMIN5 protein and its interacting partners in patient iPSC-derived neurons, suggesting a potential loss-of-function mechanism. GEMIN5 mutations result in disruption of snRNP complex assembly formation in patient iPSC neurons. Furthermore, knock down of rigor mortis, the fly homolog of human GEMIN5, leads to developmental defects, motor dysfunction, and a reduced lifespan. Interestingly, we observed that GEMIN5 variants disrupt a distinct set of transcripts and pathways as compared to SMA patient neurons, suggesting different molecular pathomechanisms. These findings collectively provide evidence that pathogenic variants in GEMIN5 perturb physiological functions and result in a neurodevelopmental delay and ataxia syndrome.
Subject(s)
Gene Expression Regulation, Developmental/genetics , Induced Pluripotent Stem Cells/metabolism , Neurodevelopmental Disorders/metabolism , Neurons/metabolism , Ribonucleoproteins, Small Nuclear/metabolism , SMN Complex Proteins/genetics , Alleles , Amino Acid Sequence , Animals , Child, Preschool , Developmental Disabilities/genetics , Drosophila/genetics , Drosophila/growth & development , Female , Gene Knockdown Techniques , Gene Ontology , HEK293 Cells , Humans , Loss of Function Mutation , Male , Muscle Hypotonia/genetics , Myoclonic Cerebellar Dyssynergia/genetics , Neurodevelopmental Disorders/diagnostic imaging , Neurodevelopmental Disorders/genetics , Neurodevelopmental Disorders/physiopathology , Pedigree , Polymorphism, Single Nucleotide , RNA-Seq , Ribonucleoproteins, Small Nuclear/genetics , Rigor Mortis/genetics , SMN Complex Proteins/metabolismABSTRACT
The BCAP31 gene, located at Xq28, encodes BAP31, which plays a role in ER-to-Golgi anterograde transport. To date, BCAP31 pathogenic variants have been reported in 12 male cases from seven families (six loss of function (LoF) and one missense). Patients had severe intellectual disability (ID), dystonia, deafness, and central hypomyelination, delineating a so-called deafness, dystonia and cerebral hypomyelination syndrome (DDCH). Female carriers are mostly asymptomatic but may present with deafness. BCAP31 is flanked by the SLC6A8 and ABCD1 genes. Contiguous deletions of BCAP31 and ABCD1 and/or SLC6A8 have been described in 12 patients. Patients with deletions including BCAP31 and SLC6A8 have the same phenotype as BCAP31 patients. Patients with deletions of BCAP31 and ABCD1 have contiguous ABCD1 and DXS1375E/BCAP31 deletion syndrome (CADDS), and demonstrate a more severe neurological phenotype with cholestatic liver disease and early death. We report 17 novel families, 14 with intragenic BCAP31 variants (LoF and missense) and three with a deletion of BCAP31 and adjacent genes (comprising two CADDS patients, one male and one symptomatic female). Our study confirms the phenotype reported in males with intragenic LoF variants and shows that males with missense variants exhibit a milder phenotype. Most patients with a LoF pathogenic BCAP31 variant have permanent or transient liver enzyme elevation. We further demonstrate that carrier females (n = 10) may have a phenotype comprising LD, ID, and/or deafness. The male with CADDS had a severe neurological phenotype, but no cholestatic liver disease, and the symptomatic female had moderate ID and cholestatic liver disease.
Subject(s)
Deafness/genetics , Hereditary Central Nervous System Demyelinating Diseases/genetics , Intellectual Disability/genetics , Loss of Function Mutation , Membrane Proteins/genetics , Phenotype , Adolescent , Adult , Child , Child, Preschool , Deafness/pathology , Female , Hereditary Central Nervous System Demyelinating Diseases/pathology , Humans , Intellectual Disability/pathology , Male , Mutation, Missense , Pedigree , SyndromeABSTRACT
During the COVID-19 pandemic, children have had markedly different clinical presentations and outcomes compared to adults. In the acute phase of infection, younger children are relatively spared the severe consequences reported in adults. Yet, they are uniquely susceptible to the newly described Multisystem Inflammatory Syndrome in Children (MIS-C). This may result from the developmental "immunodeficiency" resulting from a Th2 polarization that starts in utero and is maintained for most of the first decade of life. MIS-C may be due to IgA complexes in a Th2 environment or a Th1-like response to COVID-19 antigens that developed slowly. Alternatively, MIS-C may occur in vulnerable hosts with genetic susceptibilities in other immune and non-immune pathways. Herein, we present a brief overview of the host immune response, virologic and genetic factors, and comparable inflammatory syndromes that may explain the pathophysiology leading to drastic differences in clinical presentation and outcomes of COVID-19 between children and adults.
ABSTRACT
As of December 14, 2020, children and adolescents aged <18 years have accounted for 10.2% of coronavirus disease 2019 (COVID-19) cases reported in the United States.* Mitigation strategies to prevent infection with SARS-CoV-2, the virus that causes COVID-19, among persons of all ages, are important for pandemic control. Characterization of risk factors for SARS-CoV-2 infection among children and adolescents can inform efforts by parents, school and program administrators, and public health officials to reduce SARS-CoV-2 transmission. To assess school, community, and close contact exposures associated with pediatric COVID-19, a case-control study was conducted to compare exposures reported by parents or guardians of children and adolescents aged <18 years with SARS-CoV-2 infection confirmed by reverse transcription-polymerase chain reaction (RT-PCR) testing (case-patients) with exposures reported among those who received negative SARS-CoV-2 RT-PCR test results (control participants). Among 397 children and adolescents investigated, in-person school or child care attendance ≤14 days before the SARS-CoV-2 test was reported for 62% of case-patients and 68% of control participants and was not associated with a positive SARS-CoV-2 test result (adjusted odds ratio [aOR] = 0.8, 95% confidence interval [CI] = 0.5-1.3). Among 236 children aged ≥2 years who attended child care or school during the 2 weeks before SARS-CoV-2 testing, parents of 64% of case-patients and 76% of control participants reported that their child and all staff members wore masks inside the facility (aOR = 0.4, 95% CI = 0.2-0.8). In the 2 weeks preceding SARS-CoV-2 testing, case-patients were more likely to have had close contact with a person with known COVID-19 (aOR = 3.2, 95% CI = 2.0-5.0), have attended gatherings with persons outside their household, including social functions (aOR = 2.4, 95% CI = 1.1-5.5) or activities with other children (aOR = 3.3, 95% CI = 1.3-8.4), or have had visitors in the home (aOR = 1.9, 95% CI = 1.2-2.9) than were control participants. Close contacts with persons with COVID-19 and gatherings contribute to SARS-CoV-2 infections in children and adolescents. Consistent use of masks, social distancing, isolation of infected persons, and quarantine of those who are exposed to the virus continue to be important to prevent COVID-19 spread.