Systematically testing human HMBS missense variants to reveal mechanism and pathogenic variation.

Defects in hydroxymethylbilane synthase (HMBS) can cause acute intermittent porphyria (AIP), an acute neurological disease. Although sequencing-based diagnosis can be definitive, ∼⅓ of clinical HMBS variants are missense variants, and most clinically reported HMBS missense variants are designated as "variants of uncertain significance" (VUSs). Using saturation mutagenesis, en masse selection, and sequencing, we applied a multiplexed validated assay to both the erythroid-specific and ubiquitous isoforms of HMBS, obtaining confident functional impact scores for >84% of all possible amino acid substitutions.

Systematically testing human HMBS missense variants to reveal mechanism and pathogenic variation.

Defects in hydroxymethylbilane synthase (HMBS) can cause Acute Intermittent Porphyria (AIP), an acute neurological disease. Although sequencing-based diagnosis can be definitive, ~⅓ of clinical HMBS variants are missense variants, and most clinically-reported HMBS missense variants are designated as "variants of uncertain significance" (VUS). Using saturation mutagenesis, selection, and sequencing, we applied a multiplexed validated assay to both the erythroid-specific and ubiquitous isoforms of HMBS, obtaining confident functional impact scores for >84% of all possible amino-acid substitutions.

Very long-chain acyl-CoA dehydrogenase deficiency in a Swedish cohort: Clinical symptoms, newborn screening, enzyme activity, and genetics.

Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a recessive disorder of fatty acid beta-oxidation with variable phenotype. Patients may present during the neonatal period with lethal multi-organ failure or during adulthood with a myopathic phenotype. VLCADD is included in the Swedish newborn screening (NBS) program since 2010.

Epilepsy syndromes, etiologies, and the use of next-generation sequencing in epilepsy presenting in the first 2 years of life: A population-based study.

Objective: Population-based data on epilepsy syndromes and etiologies in early onset epilepsy are scarce. The use of next-generation sequencing (NGS) has hitherto not been reported in this context. The aim of this study is to describe children with epilepsy onset before 2 years of age, and to explore to what degree whole exome and whole genome sequencing (WES/WGS) can help reveal a molecular genetic diagnosis.

Genome-wide investigation of DNA methylation in congenital adrenal hyperplasia.

Patients with congenital adrenal hyperplasia (CAH) are at risk of long-term cognitive and metabolic sequelae with some of the effects being attributed to the chronic glucocorticoid treatment that they receive. Our pilot study investigates genome-wide DNA methylation in patients with CAH to determine whether there is preliminary evidence for epigenomic reprogramming as well as any relationship to patient outcome. Here, we analysed CD4 + T cell DNA from 28 patients with CAH (mean age = 18.

Diagnostic pitfalls in vitamin B6-dependent epilepsy caused by mutations in the gene.

Unlabelled: Vitamin B6-responsive epilepsies are a group of genetic disorders including deficiency, deficiency, and others, usually causing neonatal onset seizures resistant to treatment with common antiepileptic drugs. Recently, biallelic mutations in were shown to be a novel cause of vitamin B6-dependent epilepsy with a variable phenotype. The different vitamin B6-responsive epilepsies can be detected and distinguished by their respective biomarkers and genetic analysis.

Novel non-classic CYP21A2 variants, including combined alleles, identified in patients with congenital adrenal hyperplasia.

Objective: Congenital adrenal hyperplasia (CAH) is an inborn error of metabolism and a common disorder of sex development where >90% of all cases are due to 21-hydroxylase deficiency. Novel and rare pathogenic variants account for 5% of all clinical cases. Here, we sought to investigate the functional and structural effects of four novel (p.

Mutations in the mitochondrial tryptophanyl-tRNA synthetase cause growth retardation and progressive leukoencephalopathy.

Background: Mutations in mitochondrial aminoacyl tRNA synthetases form a subgroup of mitochondrial disorders often only perturbing brain function by affecting mitochondrial translation. Here we report two siblings with mitochondrial disease, due to compound heterozygous mutations in the mitochondrial tryptophanyl-tRNA synthetase (WARS2) gene, presenting with severe neurological symptoms but normal mitochondrial function in skeletal muscle biopsies and cultured skin fibroblasts.

Methods: Whole exome sequencing on genomic DNA samples from both subjects and their parents identified two compound heterozygous variants c.

Epigenetic Alterations Associated With Early Prenatal Dexamethasone Treatment.

Prenatal treatment with dexamethasone (DEX) reduces virilization in girls with congenital adrenal hyperplasia (CAH). It has potential short- and long-term risks and has been shown to affect cognitive functions. Here, we investigate whether epigenetic modification of DNA during early developmental stages may be a key mediating mechanism by which prenatal DEX treatment could result in poor outcomes in the offspring.

Newborn Screening for Severe Primary Immunodeficiency Diseases in Sweden-a 2-Year Pilot TREC and KREC Screening Study.

Newborn screening for severe primary immunodeficiencies (PID), characterized by T and/or B cell lymphopenia, was carried out in a pilot program in the Stockholm County, Sweden, over a 2-year period, encompassing 58,834 children. T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) were measured simultaneously using a quantitative PCR-based method on DNA extracted from dried blood spots (DBS), with beta-actin serving as a quality control for DNA quantity. Diagnostic cutoff levels enabling identification of newborns with milder and reversible T and/or B cell lymphopenia were also evaluated.

Functional and Structural Consequences of Nine Mutations Ranging from Very Mild to Severe Effects.

We present the functional and structural effects of seven novel (p.Leu12Met, p.Arg16Cys, p.

Rescue of primary ubiquinone deficiency due to a novel COQ7 defect using 2,4-dihydroxybensoic acid.

Background: Coenzyme Q is an essential mitochondrial electron carrier, redox cofactor and a potent antioxidant in the majority of cellular membranes. Coenzyme Q deficiency has been associated with a range of metabolic diseases, as well as with some drug treatments and ageing.

Methods: We used whole exome sequencing (WES) to investigate patients with inherited metabolic diseases and applied a novel ultra-pressure liquid chromatography-mass spectrometry approach to measure coenzyme Q in patient samples.

In vitro functional studies of rare CYP21A2 mutations and establishment of an activity gradient for nonclassic mutations improve phenotype predictions in congenital adrenal hyperplasia.

Background: A detailed genotype-phenotype evaluation is presented by studying the enzyme activities of five rare amino acid substitutions (Arg233Gly, Ala265Ser, Arg341Trp, Arg366Cys and Met473Ile) identified in the CYP21A2 gene in patients investigated for Congenital adrenal hyperplasia (CAH).

Objective: To investigate whether the mutations identified in the CYP21A2 gene are disease causing and to establish a gradient for the degree of enzyme impairment to improve prediction of patient phenotype.

Design And Patients: The CYP21A2 genes of seven patients investigated for CAH were sequenced and five mutations were identified.

Novel candidate genes for 46,XY gonadal dysgenesis identified by a customized 1 M array-CGH platform.

Half of all patients with a disorder of sex development (DSD) do not receive a specific molecular diagnosis. Comparative genomic hybridization (CGH) can detect copy number changes causing gene haploinsufficiency or over-expression that can lead to impaired gonadal development and gonadal DSD. The purpose of this study was to identify novel candidate genes for 46,XY gonadal dysgenesis (GD) using a customized 1 M array-CGH platform with whole-genome coverage and probe enrichment targeting 78 genes involved in sex development.

Complete Deletion of a POLG1 Allele in a Patient with Alpers Syndrome.

Mutations in the gene encoding the catalytic subunit of polymerase γ (POLG1) are a major cause of human mitochondrial disease. More than 150 different point mutations in the gene have been reported to be disease causing, resulting in a large range of clinical symptoms. Depending on the mutation or combination of mutations, disease onset can occur in early infancy or late in adult life.

Partial protoporphyrinogen oxidase (PPOX) gene deletions, due to different Alu-mediated mechanisms, identified by MLPA analysis in patients with variegate porphyria.

Variegate porphyria (VP) is an autosomal dominantly inherited hepatic porphyria. The genetic defect in the PPOX gene leads to a partial defect of protoporphyrinogen oxidase, the penultimate enzyme of heme biosynthesis. Affected individuals can develop cutaneous symptoms in sun-exposed areas of the skin and/or neuropsychiatric acute attacks.

CBX2 gene analysis in patients with 46,XY and 46,XX gonadal disorders of sex development.

Objective: To investigate a cohort of patients with gonadal disorders of sex development (DSD) for causative CBX2 gene mutations and or gene copy number changes.

Design: Genetic association study.

Setting: University laboratory and tertiary university-based referral center.

Multigeneration Inheritance through Fertile XX Carriers of an NR0B1 (DAX1) Locus Duplication in a Kindred of Females with Isolated XY Gonadal Dysgenesis.

A 160 kb minimal common region in Xp21 has been determined as the cause of XY gonadal dysgenesis, if duplicated. The region contains the MAGEB genes and the NR0B1 gene; this is the candidate for gonadal dysgenesis if overexpressed. Most patients present gonadal dysgenesis within a more complex phenotype.