COVID-19 in Unvaccinated patients with inherited metabolic disorders: A single center experience.

Patients with certain inherited metabolic disorders (IMD) are at high risk for metabolic decompensation with exposure to infections. The COVID-19 pandemic has been particularly challenging for health care providers dealing with IMD patients, in view of its unpredictable consequences in these patients. There is limited data in literature on evaluating the impact and the outcome of COVID-19 infection in these patients. This cross-sectional retrospective study on a large cohort of unvaccinated IMD patients, reviewed the incidence of COVID-19 infection, disease manifestation and outcome during the pandemic between November 2019 and July 2021. In this cohort of 1058 patients, 11.7% (n = 124) were infected with COVID-19. Their median age was 16 years (age range 2-42); 57% (n = 71) were males. Post-exposure positive test was noted in 78% (n = 97) patients, while 19% (n = 24) had symptomatic diagnosis and three patients tested positive during pre-hospital visits screening. Most patients, 68.5% (n = 85) had mild COVID-19 related symptoms such as fever, cough, headache and diarrhea while 13.7% (n = 17) patients had no symptoms. Of twenty-two patients (17.7%) who required hospitalization, 16 were adults with various intoxication and energy metabolism disorders, who developed IMD related complications such as metabolic acidosis, hyperammonemia, acute pancreatitis, hypoglycemia, rhabdomyolysis and thrombosis. Ten patients needed intensive care management. The cohort death rate was 2.4% (3 patients). Overall, the clinical course of COVID-19 infection in these IMD patients was relatively mild except for patients with intoxication and energy metabolism disorders who had high risk of developing acute metabolic decompensation with severe complications.

Emergency management of critically ill adult patients with inherited metabolic disorders.

INTRODUCTION: An increasing number of pediatric patients with inherited metabolic disorders are reaching adulthood. In addition, many patients are diagnosed for the first time in adult life due to improved awareness of these disorders and the availability of advanced diagnostic technology. Knowledge of these inherited metabolic disorders in adults is crucial for the emergency physician to promptly recognize their acute illness and appropriately manage them in the emergency department. OBJECTIVE: This review provides an overview of various inherited metabolic disorders which present to the emergency department with acute metabolic decompensation. EVALUATION AND MANAGEMENT: Acute illness in these patients is often triggered by a catabolic event such as intercurrent illness, fasting, postpartum, or use of certain medication. It may present in a variety of ways related to severe hyperammonemia, metabolic acidosis, leucine encephalopathy or hypoglycemia. In this review, we describe the clinical presentation, evaluation and immediate management of their critical illness in the emergency department. CONCLUSION: Acute metabolic decompensation is a life-threatening condition. The emergency physician is usually the first provider to evaluate these patients when they present to the emergency department. Early recognition of their illness and prompt management of these cases improve patient outcomes.

Clinical, radiological, and genetic characterization of SLC13A5 variants in Saudi families: Genotype phenotype correlation and brief review of the literature.

Background: SLC13A5 (solute carrier family 13, member 5) encodes sodium/citrate cotransporter, which mainly localizes in cellular plasma membranes in the frontal cortex, retina, and liver. Pathogenic variants of the gene cause an autosomal recessive syndrome known as "developmental and epileptic encephalopathy 25 with amelogenesis imperfecta." Results: Here, we have investigated six patients from three different consanguineous Saudi families. The affected individuals presented with neonatal seizures, developmental delay, and significant defects in tooth development. Some patients showed other clinical features such as muscle weakness, motor difficulties, intellectual disability, microcephaly, and speech problems in addition to additional abnormalities revealed by electroencephalography (EEGs) and magnetic resonance imaging (MRI). One of the MRI findings was related to cortical thickening in the frontal lobe. To diagnose and study the genetic defects of the patients, whole exome sequencing (WES) coupled with confirmatory Sanger sequencing was utilized. Iterative filtering identified two variants of SLC13A5, one of which is novel, in the families. Families 1 and 2 had the same insertion (a previously reported mutation), leading to a frameshift and premature stop codon. The third family had a novel splice site variant. Confirmatory Sanger sequencing corroborated WES results and indicated full segregation of the variants in the corresponding families. The patients' conditions were poorly controlled by multiple antiepileptics as they needed constant care. Conclusion: Considering that recessive mutations are common in the Arab population, SLC13A5 screening should be prioritized in future patients harboring similar symptoms including defects in molar development.

Lessons Learned from Large-Scale, First-Tier Clinical Exome Sequencing in a Highly Consanguineous Population.

We report the results of clinical exome sequencing (CES) on >2,200 previously unpublished Saudi families as a first-tier test. The predominance of autosomal-recessive causes allowed us to make several key observations. We highlight 155 genes that we propose to be recessive, disease-related candidates. We report additional mutational events in 64 previously reported candidates (40 recessive), and these events support their candidacy. We report recessive forms of genes that were previously associated only with dominant disorders and that have phenotypes ranging from consistent with to conspicuously distinct from the known dominant phenotypes. We also report homozygous loss-of-function events that can inform the genetics of complex diseases. We were also able to deduce the likely causal variant in most couples who presented after the loss of one or more children, but we lack samples from those children. Although a similar pattern of mostly recessive causes was observed in the prenatal setting, the higher proportion of loss-of-function events in these cases was notable. The allelic series presented by the wealth of recessive variants greatly expanded the phenotypic expression of the respective genes. We also make important observations about dominant disorders; these observations include the pattern of de novo variants, the identification of 74 candidate dominant, disease-related genes, and the potential confirmation of 21 previously reported candidates. Finally, we describe the influence of a predominantly autosomal-recessive landscape on the clinical utility of rapid sequencing (Flash Exome). Our cohort's genotypic and phenotypic data represent a unique resource that can contribute to improved variant interpretation through data sharing.

Spectrum of bone marrow pathology and hematological abnormalities in methylmalonic acidemia.

Patients with isolated methylmalonic acidemia (MMA) may present with a wide range of hematological complications including anemia, leukopenia, thrombocytopenia, and pancytopenia. However, there are very limited data on the development of hemophagocytosis or myelodysplasia in these patients. We report three patients with isolated MUT related MMA who presented with severe refractory pancytopenia during acute illness. Their bone marrow examination revealed a wide spectrum of pathology varying from bone marrow hypoplasia, hemophagocytosis to myelodysplasia with ring sideroblasts. We discuss their management and outcome. This report emphasizes the need for bone marrow examination in these patients with refractory or unexplained severe cytopenia, to confirm bone marrow pathology, and to rule out other diseases with similar clinical presentation for a better clinical outcome.

In search of triallelism in Bardet-Biedl syndrome.

Bardet-Biedl syndrome (BBS) is a model disease for ciliopathy in humans. The remarkable genetic heterogeneity that characterizes this disease is consistent with accumulating data on the interaction between the proteins encoded by the 14 BBS genes identified to date. Previous reports suggested that such interaction may also extend to instances of oligogenic inheritance in the form of triallelism which defies the long held view of BBS as an autosomal recessive disease. In order to investigate the magnitude of triallelism in BBS, we conducted a comprehensive analysis of all 14 BBS genes as well as the CCDC28B-modifier gene in a cohort of 29 BBS families, most of which are multiplex. Two in trans mutations in a BBS gene were identified in each of these families for a total of 20 mutations including 12 that are novel. In no instance did we observe two mutations in unaffected members of a given family, or observe the presence of a third allele that convincingly acted as a modifier of penetrance and supported the triallelic model of BBS. In addition to presenting a comprehensive genotype/phenotype overview of a large set of BBS mutations, including the occurrence of nonsyndromic retinitis pigmentosa in a family with a novel BBS9 mutation, our study argues in favor of straightforward autosomal recessive BBS in most cases.