Addition of galactose-1-phosphate measurement enhances newborn screening for classical galactosemia.

Galactosemia is an inborn disorder of carbohydrate metabolism of which early detection can prevent severe illness. Although the assay for galactose-1-phosphate uridyltransferase (GALT) enzyme activity has been available since the 1960s, many issues prevented it from becoming universal. In order to develop the Israeli newborn screening pilot algorithm for galactosemia, flow injection analysis tandem mass spectrometry measurement of galactose-1-phosphate in archived dried blood spots from newborns with classical galactosemia, galactosemia variants, epimerase deficiency, and normal controls, was conducted. Out of 431 330 newborns screened during the pilot study (30 months), two with classical galactosemia and four with epimerase deficiency were identified and confirmed. Five false positives and no false negatives were recorded. Following this pilot study, the Israeli final and routine newborn screening algorithm, as recommended by the Advisory Committee to the National Newborn Screening Program, now consists of galactose-1-phosphate measurement integrated into the routine tandem mass spectrometry panel as the first-tier screening test, and GALT enzyme activity as the second-tier performed to identify only newborns suspected to be at risk for classical galactosemia. The GALT enzyme activity cut-off used in the final algorithm was lowered in order to avoid false positives.

Primary Coenzyme Q deficiency Due to Novel ADCK3 Variants, Studies in Fibroblasts and Review of Literature.

Primary deficiency of coenzyme Q10 (CoQ10 ubiquinone), is classified as a mitochondrial respiratory chain disorder with phenotypic variability. The clinical manifestation may involve one or multiple tissue with variable severity and presentation may range from infancy to late onset. ADCK3 gene mutations are responsible for the most frequent form of hereditary CoQ10 deficiency (Q10 deficiency-4 OMIM #612016) which is mainly associated with autosomal recessive spinocerebellar ataxia (ARCA2, SCAR9). Here we provide the clinical, biochemical and genetic investigation for unrelated three nuclear families presenting an autosomal form of Spino-Cerebellar Ataxia due to novel mutations in the ADCK3 gene. Using next generation sequence technology we identified a homozygous Gln343Ter mutation in one family with severe, early onset of the disease and compound heterozygous mutations of Gln343Ter and Ser608Phe in two other families with variable manifestations. Biochemical investigation in fibroblasts showed decreased activity of the CoQ dependent mitochondrial respiratory chain enzyme succinate cytochrome c reductase (complex II + III). Exogenous CoQ slightly improved enzymatic activity, ATP production and decreased oxygen free radicals in some of the patient's cells. Our results are presented in comparison to previously reported mutations and expanding the clinical, molecular and biochemical spectrum of ADCK3 related CoQ10 deficiencies.

Rapid exome sequencing for children with severe acute encephalopathy - A case series.

Increasingly, next-generation sequencing (NGS) is becoming an invaluable tool in the diagnosis of unexplained acute neurological disorders, such as acute encephalopathy/encephalitis. Here, we describe a brief series of pediatric patients who presented at the pediatric intensive care unit with severe acute encephalopathy, initially suspected as infectious or inflammatory but subsequently diagnosed with a monogenic disorder. Rapid exome sequencing was performed during the initial hospitalization of three unrelated patients, and results were delivered within 7-21 days. All patients were previously healthy, 1.5-3 years old, of Muslim Arab descent, with consanguineous parents. One patient presenting with acute necrotizing encephalopathy (ANEC). Her sister presented with ANEC one year prior. Exome sequencing was diagnostic in all three patients. All were homozygous for pathogenic and likely-pathogenic variants associated with recessive disorders; MOCS2, NDUFS8 and DBR1. Surprisingly, the initial workup was not suggestive of the final diagnosis. This case series demonstrates that the use of rapid exome sequencing is shifting the paradigm of diagnostics even in critical care situations and should be considered early on in children with acute encephalopathy. A timely diagnosis can direct initial treatment as well as inform decisions regarding long-term care.

The Genetics of Glucose-6-Phosphate-Dehydrogenase (G6PD) and Uridine Diphosphate Glucuronosyl Transferase 1A1 (UGT1A1) Promoter Gene Polymorphism in Relation to Quantitative Biochemical G6PD Activity Measurement and Neonatal Hyperbilirubinemia.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and polymorphism in uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1) were associated with significant neonatal hyperbilirubinemia (NHB) and increased risk for kernicterus. However, quantitative screening tests for G6PD enzyme activity proved unsatisfactory in estimating the risk for significant NHB, especially in heterozygous females that could present phenotype overlap between normal homozygotes, heterozygotes, and deficient homozygotes, resulting in a continuum of intermediate G6PD activity. OBJECTIVE: To examine the association of genotype and phenotype in newborns with decreased G6PD activity and its relation to NHB. STUDY DESIGN: Quantitative G6PD enzyme activities were measured on umbilical cord blood samples. After accepting parental consent, samples were analyzed for G6PD mutations and UGT1A1 gene polymorphisms (number of TA repeats in the UGT1A1 promoter). The associations to quantitative G6PD activity and bilirubin levels were assessed. RESULTS: 28 females and 27 males were studied. The Mediterranean mutation (NM_001360016.2(G6PD): c.563C>T (p.Ser188Phe)) was responsible for most cases of G6PD deficiency (20 hemizygous males, 3 homozygous and 16 heterozygous females). The association between this mutation, decreased G6PD activity and higher bilirubin levels was confirmed. Heterozygosity to 6/7 TA repeats in the UGT1A1 promoter was associated with increased NHB, especially in female newborns with G6PD deficiency. However, it seems that the interaction between G6PD deficiency, UGT1A1 promoter polymorphism, and NHB is more complex, possibly involving other genetic interactions, not yet described. Despite genotyping females with G6PD deficiency, the overlap between the upper range of borderline and the lower range of normal G6PD activity could not be resolved. CONCLUSIONS: The results of this study highlight the possibility for future implementation of molecular genetic screening to identify infants at risk for significant NHB, especially UGT1A1 polymorphism in heterozygous females with borderline G6PD deficiency. However, further studies are needed before such screening could be applicable to daily practice.

PTRH2 Gene Variants: Recent Review of the Phenotypic Features and Their Bioinformatics Analysis.

Peptidyl-tRNA hydrolase 2 (PTRH2) is an evolutionarily highly conserved mitochondrial protein. The biallelic mutations in the PTRH2 gene have been suggested to cause a rare autosomal recessive disorder characterized by an infantile-onset multisystem neurologic endocrine and pancreatic disease (IMNEPD). Patients with IMNEPD present varying clinical manifestations, including global developmental delay associated with microcephaly, growth retardation, progressive ataxia, distal muscle weakness with ankle contractures, demyelinating sensorimotor neuropathy, sensorineural hearing loss, and abnormalities of thyroid, pancreas, and liver. In the current study, we conducted an extensive literature review with an emphasis on the variable clinical spectrum and genotypes in patients. Additionally, we reported on a new case with a previously documented mutation. A bioinformatics analysis of the various PTRH2 gene variants was also carried out from a structural perspective. It appears that the most common clinical characteristics among all patients include motor delay (92%), neuropathy (90%), distal weakness (86.4%), intellectual disability (84%), hearing impairment (80%), ataxia (79%), and deformity of head and face (~70%). The less common characteristics include hand deformity (64%), cerebellar atrophy/hypoplasia (47%), and pancreatic abnormality (35%), while the least common appear to be diabetes mellitus (~30%), liver abnormality (~22%), and hypothyroidism (16%). Three missense mutations were revealed in the PTRH2 gene, the most common one being Q85P, which was shared by four different Arab communities and was presented in our new case. Moreover, four different nonsense mutations in the PTRH2 gene were detected. It may be concluded that disease severity depends on the PTRH2 gene variant, as most of the clinical features are manifested by nonsense mutations, while only the common features are presented by missense mutations. A bioinformatics analysis of the various PTRH2 gene variants also suggested the mutations to be deleterious, as they seem to disrupt the structural confirmation of the enzyme, leading to loss of stability and functionality.

Umbilical Cord and Neonatal Transthyretin and Their Relationship to Growth and Nutrition in Preterm Infants.

BACKGROUND: Transthyretin (TTR), also known as prealbumin, has been suggested as an indicator of protein and nutritional status. OBJECTIVE: The aim of this study was to examine the maternal and umbilical cord (UC) TTR in relation to intrauterine growth, and the serum TTR of preterm infants in relation to nutritional status and growth. METHODS: After application of exclusion criteria, 49 preterm infants (mean gestational age and birth-weight 32.9±2.9 weeks and 1822±556 g) were included in the study. Transthyretin was sampled at birth and on days 14, 28, and at discharge with growth parameters and nutritional laboratory test results. RESULTS: Mean UC and maternal TTR were positively correlated (8.5±2.4 mg/dL and 20.4±7.0 mg/dL, r=0.31, P=0.07). Umbilical cord TTR was neither an index of maturity nor of intrauterine growth. Umbilical cord TTR was higher in females (9.4±2.6 versus 7.6±1.8 mg/dL, P=0.015). Maternal TTR was lower in twin pregnancies (16.8±4.9 versus 22.5±7.3 mg/dL, P=0.007). Although TTR levels gradually increased over time in correlation with post-menstrual and chronological ages (r=0.24, P=0.011 and r=0.40, P<0.001, respectively), there was no correlation to weight gain (r=0.10, P=0.41), nutritional status, protein intake, or nutritional laboratory test results. The only significant correlations were between TTR and glucose and triglycerides levels (r=0.51, P<0.001 for both). CONCLUSIONS: Although TTR levels increased over time, we could not demonstrate significant correlations between TTR and indices of the nutritional status in preterm infants at birth or during the neonatal course.

The Effects of Rudeness on NICU Medical Teams Studied by a New Tool for the Assessment of Decision-Making Group Dynamics.

BACKGROUND: Group decision-making can be placed on a continuum of group dynamics, between Groupthink and Polythink. OBJECTIVE: To present a new assessment tool for the characterization of medical teams' decision-making group dynamics, and test it to study the effects of exposure to rudeness on various types of group dynamics. METHODS: Three judges who watched videotapes of critical care simulations evaluated 24 neonatal intensive care unit teams' decision-making processes. Teams were rated using the new assessment tool, especially designed for this quantitative study, based on items adapted from symptoms of Polythink and Groupthink. RESULTS: Measures of reliability, inter-rater agreement and internal consistency, were reasonably good. Confirmatory factor analysis refined the tool and verified that the symptoms in each category (Polythink or Groupthink) of the refined 14 items' assessment tool were indeed measures of the construct. The average General Score was in the range of the balanced dynamic on the continuum, and without tendency towards one of the extremities (Groupthink or Polythink). No significant effect of exposure to rudeness on group dynamics was found. CONCLUSIONS: This is a first attempt at using quantitative methods to evaluate decision-making group dynamics in medicine, by adapting symptoms of Groupthink and Polythink as items in a structured assessment tool. It suggests a new approach to understanding decision-making processes of medical teams. The assessment tool seems to be a promising, feasible and reasonably reliable research tool to be further studied in medicine and other disciplines engaged in decision-making.

Expanding the spectrum of endocrinopathies identified in Schaaf-Yang syndrome - A case report and review of the literature.

Schaaf-Yang syndrome is a genetic disorder caused by mutations in the paternal allele of the MAGEL2 gene. Developmental delay, feeding difficulties, joint contractures and a high prevalence of autism spectrum disorders are characteristic of the syndrome. Endocrine abnormalities include mostly various pituitary hormonal deficiencies, presenting as hypoglycemia in 48% of reported cases. Persistent hyperinsulinism was only described in two siblings and responded to diazoxide treatment. We describe a unique case of an infant with Schaaf-Yang syndrome that presented with persistent hyperinsulinism unresponsive to diazoxide. Furthermore, we conducted a literature review of the endocrine abnormalities described in MAGEL2 related disorders. The case presented expands the clinical phenotype of Schaaf-Yang syndrome and emphasizes the importance of endocrine follow-up in these patients. Further investigation into the role of MAGEL2 in the regulation of pancreatic beta-cell insulin secretion, will improve our understanding of the abnormalities in glucose regulation in this syndrome.

Deficiency of MFSD7c results in microcephaly-associated vasculopathy in Fowler syndrome.

Several missense mutations in the orphan transporter FLVCR2 have been reported in Fowler syndrome. Affected subjects exhibit signs of severe neurological defects. We identified the mouse ortholog Mfsd7c as a gene expressed in the blood-brain barrier. Here, we report the characterizations of Mfsd7c-KO mice and compare these characterizations to phenotypic findings in humans with biallelic FLVCR2 mutations. Global KO of Mfsd7c in mice resulted in late-gestation lethality, likely due to CNS phenotypes. We found that the angiogenic growth of CNS blood vessels in the brain of Mfsd7c-KO embryos was inhibited in cortical ventricular zones and ganglionic eminences. Vascular tips were dilated and fused, resulting in glomeruloid vessels. Nonetheless, CNS blood vessels were intact, without hemorrhage. Both embryos and humans with biallelic FLVCR2 mutations exhibited reduced cerebral cortical layers, enlargement of the cerebral ventricles, and microcephaly. Transcriptomic analysis of Mfsd7cK-KO embryonic brains revealed upregulation of genes involved in glycolysis and angiogenesis. The Mfsd7c-KO brain exhibited hypoxia and neuronal cell death. Our results indicate that MFSD7c is required for the normal growth of CNS blood vessels and that ablation of this gene results in microcephaly-associated vasculopathy in mice and humans.

Pathogenic variants in glutamyl-tRNAGln 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-tRNAGln). mt-tRNAGln 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. Here, we describe nine patients from five families with genetic defects in a GatCAB complex subunit, including QRSL1, GATB, and GATC, each showing a lethal metabolic cardiomyopathy syndrome. Functional studies reveal combined respiratory chain enzyme deficiencies and mitochondrial dysfunction. Aminoacylation of mt-tRNAGln and mitochondrial protein translation are deficient in patients' fibroblasts cultured in the absence of glutamine but restore in high glutamine. Lentiviral rescue experiments and modeling in S. cerevisiae homologs confirm pathogenicity. Our study completes a decade of investigations on mitochondrial aminoacylation disorders, starting with DARS2 and ending with the GatCAB complex.