41-Year-Old Male with Sub-Acute Encephalopathy, Seizures, and End Stage Renal Disease: A Unifying Diagnosis and Response to Therapy.

We describe a case of a 41-year-old male with a history of end-stage renal disease, hypertension, epilepsy, ischemic stroke, and traumatic brain injury transferred to our tertiary care center for subacute, progressive cognitive impairment. He was found to have disproportionate brain atrophy, focal seizures, and refractory hypertension. Given suspicion for an underlying genetic etiology, a genetic panel for progressive renal disease was sent, revealing two known pathogenic variants in a gene for a cobalamin metabolism disorder, Cobalamin C deficiency.

Continued improvement in disease manifestations of acid sphingomyelinase deficiency for adults with up to 2 years of olipudase alfa treatment: open-label extension of the ASCEND trial.

Background: Olipudase alfa is a recombinant human acid sphingomyelinase enzyme replacement therapy for non-central-nervous-system manifestations of acid sphingomyelinase deficiency (ASMD). The ASCEND randomized placebo-controlled trial in adults with ASMD demonstrated reductions in sphingomyelin storage, organomegaly, interstitial lung disease and impaired diffusion capacity of the lung (DL), during the first year of olipudase alfa treatment. In an ongoing open-label extension of the ASCEND trial, individuals in the placebo group crossed over to olipudase alfa, and those in the olipudase alfa group continued treatment.

Diagnostic yield of pediatric and prenatal exome sequencing in a diverse population.

The diagnostic yield of exome sequencing (ES) has primarily been evaluated in individuals of European ancestry, with less focus on underrepresented minority (URM) and underserved (US) patients. We evaluated the diagnostic yield of ES in a cohort of predominantly US and URM pediatric and prenatal patients suspected to have a genetic disorder. Eligible pediatric patients had multiple congenital anomalies and/or neurocognitive disabilities and prenatal patients had one or more structural anomalies, disorders of fetal growth, or fetal effusions.

Functional genomics of OCTN2 variants informs protein-specific variant effect predictor for Carnitine Transporter Deficiency.

Genetic variants in , encoding the membrane carnitine transporter OCTN2, cause the rare metabolic disorder Carnitine Transporter Deficiency (CTD). CTD is potentially lethal but actionable if detected early, with confirmatory diagnosis involving sequencing of . Interpretation of missense variants of uncertain significance (VUSs) is a major challenge.

A randomized, placebo-controlled clinical trial evaluating olipudase alfa enzyme replacement therapy for chronic acid sphingomyelinase deficiency (ASMD) in adults: One-year results.

Purpose: This trial aimed to assess the efficacy and safety of olipudase alfa enzyme replacement therapy for non-central nervous system manifestations of acid sphingomyelinase deficiency (ASMD) in adults.

Methods: A phase 2/3, 52 week, international, double-blind, placebo-controlled trial (ASCEND; NCT02004691/EudraCT 2015-000371-26) enrolled 36 adults with ASMD randomized 1:1 to receive olipudase alfa or placebo intravenously every 2 weeks with intrapatient dose escalation to 3 mg/kg. Primary efficacy endpoints were percent change from baseline to week 52 in percent predicted diffusing capacity of the lung for carbon monoxide and spleen volume (combined with splenomegaly-related score in the United States).

Fetal therapies and trials for lysosomal storage diseases: a survey of attitudes of parents and patients.

Background: Lysosomal storage diseases (LSDs) are inherited metabolic disorders that may lead to severe multi-organ disease. Current ERTs are limited by anti-drug antibodies, the blood-brain barrier, and early disease onset and progression before ERT is started. We have opened a phase I clinical trial of enzyme replacement therapy (ERT) for fetuses with LSDs (NCT04532047).

Application of full-genome analysis to diagnose rare monogenic disorders.

Current genetic testenhancer and narrows the diagnostic intervals for rare diseases provide a diagnosis in only a modest proportion of cases. The Full-Genome Analysis method, FGA, combines long-range assembly and whole-genome sequencing to detect small variants, structural variants with breakpoint resolution, and phasing. We built a variant prioritization pipeline and tested FGA's utility for diagnosis of rare diseases in a clinical setting.

The Use of Whole Genome and Exome Sequencing for Newborn Screening: Challenges and Opportunities for Population Health.

Newborn screening (NBS) is a population-based program with a goal of reducing the burden of disease for conditions with significant clinical impact on neonates. Screening tests were originally developed and implemented one at a time, but newer methods have allowed the use of multiplex technologies to expand additions more rapidly to standard panels. Recent improvements in next-generation sequencing are also evolving rapidly from first focusing on individual genes, then panels, and finally all genes as encompassed by whole exome and genome sequencing.

Opportunities and challenges for the computational interpretation of rare variation in clinically important genes.

Genome sequencing is enabling precision medicine-tailoring treatment to the unique constellation of variants in an individual's genome. The impact of recurrent pathogenic variants is often understood, however there is a long tail of rare genetic variants that are uncharacterized. The problem of uncharacterized rare variation is especially acute when it occurs in genes of known clinical importance with functionally consequential variants and associated mechanisms.

Genomic Analysis of Historical Cases with Positive Newborn Screens for Short-Chain Acyl-CoA Dehydrogenase Deficiency Shows That a Validated Second-Tier Biochemical Test Can Replace Future Sequencing.

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare autosomal recessive disorder of β-oxidation caused by pathogenic variants in the gene. Analyte testing for SCADD in blood and urine, including newborn screening (NBS) using tandem mass spectrometry (MS/MS) on dried blood spots (DBSs), is complicated by the presence of two relatively common variants (c.625G>A and c.

The role of exome sequencing in newborn screening for inborn errors of metabolism.

Public health newborn screening (NBS) programs provide population-scale ascertainment of rare, treatable conditions that require urgent intervention. Tandem mass spectrometry (MS/MS) is currently used to screen newborns for a panel of rare inborn errors of metabolism (IEMs). The NBSeq project evaluated whole-exome sequencing (WES) as an innovative methodology for NBS.

Conducting an investigator-initiated randomized double-blinded intervention trial in acute decompensation of inborn errors of metabolism: Lessons from the N-Carbamylglutamate Consortium.

Organic acidemias and urea cycle disorders are ultra-rare inborn errors of metabolism characterized by episodic acute decompensation, often associated with hyperammonemia, resulting in brain edema and encephalopathy. Retrospective reports and translational studies suggest that N-carbamylglutamate (NCG) may be effective in reducing ammonia levels during acute decompensation in two organic acidemias, propionic and methylmalonic acidemia (PA and MMA), and in two urea cycle disorders, carbamylphosphate synthetase 1 and ornithine transcarbamylase deficiency (CPSD and OTCD). We established the 9-site N-carbamylglutamate Consortium (NCGC) in order to conduct two randomized double-blind, placebo-controlled trials of NCG in acute hyperammonemia of PA, MMA, CPSD and OTCD.

Pathogenic variants in glutamyl-tRNA amidotransferase subunits cause a lethal mitochondrial cardiomyopathy disorder.

Mitochondrial protein synthesis requires charging mt-tRNAs with their cognate amino acids by mitochondrial aminoacyl-tRNA synthetases, with the exception of glutaminyl mt-tRNA (mt-tRNA). mt-tRNA is indirectly charged by a transamidation reaction involving the GatCAB aminoacyl-tRNA amidotransferase complex. Defects involving the mitochondrial protein synthesis machinery cause a broad spectrum of disorders, with often fatal outcome.

Cobalamin D Deficiency Identified Through Newborn Screening.

Cobalamin D deficiency (cblD) is one of the least common cobalamin metabolism disorders. It may result in isolated homocystinuria, isolated methylmalonic aciduria, or combined methylmalonic aciduria and homocystinuria (cblD-combined). Only seven cases of the combined cblD form have been reported to date.

Laboratory analysis of organic acids, 2018 update: a technical standard of the American College of Medical Genetics and Genomics (ACMG).

Organic acid analysis detects accumulation of organic acids in urine and other body fluids and is a crucial first-tier laboratory test for a broad spectrum of inborn errors of metabolism. It is also frequently ordered as follow-up for a positive newborn screen result, as recommended by American College of Medical Genetics and Genomics newborn screening ACTion sheets and algorithms. The typical assay is performed by gas chromatography-mass spectrometry.

Potential Misdiagnosis of Hyperhomocysteinemia due to Cystathionine Beta-Synthase Deficiency During Pregnancy.

Extreme hyperhomocysteinemia with low cystathionine and cysteine is virtually diagnostic of cystathionine beta-synthase (CBS) deficiency since remethylation defects and hypermethioninemia due to other inborn errors cause elevated serum cystathionine. However, a pregnant CBS deficient patient was found to have elevated cystathionine in addition to elevated total homocysteine and methionine at 23 weeks of gestation and post-delivery cystathionine decreased to the lower level of normal. A second patient with cystathionine values during gestation also showed a rise from the low pre-pregnant value to massive elevation by delivery.

The M405V allele of the glutaryl-CoA dehydrogenase gene is an important marker for glutaric aciduria type I (GA-I) low excretors.

Glutaric aciduria type I (GA-I) is an autosomal recessive organic aciduria resulting from a functional deficiency of glutaryl-CoA dehydrogenase, encoded by GCDH. Two clinically indistinguishable diagnostic subgroups of GA-I are known; low and high excretors (LEs and HEs, respectively). Early medical and dietary interventions can result in significantly better outcomes and improved quality of life for patients with GA-I.

Frequency and Pathophysiology of Acute Liver Failure in Ornithine Transcarbamylase Deficiency (OTCD).

Background: Acute liver failure (ALF) has been reported in ornithine transcarbamylase deficiency (OTCD) and other urea cycle disorders (UCD). The frequency of ALF in OTCD is not well-defined and the pathogenesis is not known.

Aim: To evaluate the prevalence of ALF in OTCD, we analyzed the Swiss patient cohort.

Pyridoxine-Dependent Epilepsy: An Expanding Clinical Spectrum.

Background: Pyridoxine-dependent epilepsy is a rare autosomal recessive epileptic encephalopathy caused by antiquitin (ALDH7A1) deficiency. In spite of adequate seizure control, 75% of patients suffer intellectual developmental disability. Antiquitin deficiency affects lysine catabolism resulting in accumulation of α-aminoadipic semialdehyde/pyrroline 6' carboxylate and pipecolic acid.