Newborn screening algorithm distinguishing potential symptomatic isovaleric acidemia from asymptomatic newborns.

Newborn screening (NBS) for isovaleric acidemia (IVA) reduces mortality and morbidity; however, it has also resulted in the detection of individuals with an asymptomatic or mild presentation for which early detection via newborn screening has not been proven to alter neurological outcome. We reevaluated biochemical and molecular data for newborns flagged positive for IVA in aim of developing a new screening algorithm to exclude the latter from positive screening. Among 2 794 365 newborns underwent routine newborn screening in Israel, 412 flagged positive for IVA, of which, 371 were false positives on recall sample testing and 41 positive newborns were referred to the clinic. 38/41 have biochemical and molecular confirmation in keeping with IVA. Among the 38 patients, 32% (12/38) were classified as symptomatic while, 68% (26/38) were classified as asymptomatic. 69% of the latter group harbor the known variant associated with mild potentially asymptomatic phenotype, c.932C>T; p. Ala311Val. Among asymptomatic patients, only 46% (12/26) are currently treated. Two novel variants have been detected in the IVD gene: c.487G>A; p. Ala163Thr and c.985A>G; p. Met329Val. Cut-off recalculation, of referred newborns' initial biochemical results, after classifying the referred patients to two binary groups of symptomatic and asymptomatic, resulted in an improved NBS algorithm comprising of C5 >5 µM and C5/C2>0.2 and C5/C3>4 flagging only those likely to have the classic symptomatic phenotype.

The natural history of dihydrolipoamide dehydrogenase deficiency in Israel.

Dihydrolipoamide dehydrogenase (DLD) deficiency is an ultra-rare autosomal-recessive inborn error of metabolism, affecting no less than five mitochondrial multienzyme complexes. With approximately 30 patients reported to date, DLD deficiency was associated with three major clinical presentations: an early-onset encephalopathic phenotype with metabolic acidosis, a predominantly hepatic presentation with liver failure, and a rare myopathic phenotype. To elucidate the demographic, phenotypic, and molecular characteristics of patients with DLD deficiency within the Israeli population, data were collected from metabolic disease specialists in four large tertiary medical centers in the center and south of Israel. Pediatric and adult patients with biallelic variants in DLD were included in the study. A total of 53 patients of 35 families were included in the cohort. Age at presentation ranged between birth and 10 years. Wide phenotypic variability was observed, from asymptomatic individuals in their sixth decade of life, to severe, neonatal-onset disease with devastating neurological sequelae. Six DLD variants were noted, the most common of which was the c.685G>T (p.G229C) variant in homozygous form (24/53 patients, 45.3%; 13/35 families), observed mostly among patients of Ashkenazi-Jewish descent, followed by the homozygous c.1436A>T (p.D479V) variant, found in 20 patients of Bedouin descent (37.7%; 16/35 families). Overall, patients did not necessarily present as one of the previously described distinct clinical phenotypes. DLD deficiency is a panethnic disorder, with significant phenotypic variability, and comprises a continuum, rather than three distinct clinical presentations.

Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein TIMM50.

TIMM50, an essential TIM23 complex subunit, is suggested to facilitate the import of ∼60% of the mitochondrial proteome. In this study, we characterized a TIMM50 disease causing mutation in human fibroblasts and noted significant decreases in TIM23 core protein levels (TIMM50, TIMM17A/B, and TIMM23). Strikingly, TIMM50 deficiency had no impact on the steady state levels of most of its putative substrates, suggesting that even low levels of a functional TIM23 complex are sufficient to maintain the majority of TIM23 complex-dependent mitochondrial proteome. As TIMM50 mutations have been linked to severe neurological phenotypes, we aimed to characterize TIMM50 defects in manipulated mammalian neurons. TIMM50 knockdown in mouse neurons had a minor effect on the steady state level of most of the mitochondrial proteome, supporting the results observed in patient fibroblasts. Amongst the few affected TIM23 substrates, a decrease in the steady state level of components of the intricate oxidative phosphorylation and mitochondrial ribosome complexes was evident. This led to declined respiration rates in fibroblasts and neurons, reduced cellular ATP levels and defective mitochondrial trafficking in neuronal processes, possibly contributing to the developmental defects observed in patients with TIMM50 disease. Finally, increased electrical activity was observed in TIMM50 deficient mice neuronal cells, which correlated with reduced levels of KCNJ10 and KCNA2 plasma membrane potassium channels, likely underlying the patients' epileptic phenotype.

Long-term administration of intravenous Trappsol® Cyclo™ (HP-ß-CD) results in clinical benefits and stabilization or slowing of disease progression in patients with Niemann-Pick disease type C1: Results of an international 48-week Phase I/II trial.

Background: Niemann-Pick disease type C (NPC) is a rare, fatal, pan-ethnic, autosomal recessive lysosomal storage disease characterized by progressive major organ failure and neurodegeneration. Preclinical studies confirmed a critical role of systemically administered hydroxypropyl-ß-cyclodextrin (HP-ß-CD; Trappsol® Cyclo™) in cholesterol metabolism and homeostasis in peripheral tissues of the body, including the liver, and in the central nervous system (CNS). Herein, the pharmacokinetics (PK), safety, and efficacy of HP-ß-CD, and biomarkers of NPC were assessed in pediatric and adult patients with NPC1. Methods: This was a multicenter, Phase I/II, randomized, double-blind, parallel-group, 48-week study (ClinicalTrials.gov identifier NCT02912793) to compare the PK of three different single intravenous (IV) doses of HP-ß-CD in pediatric and adult patients with NPC1 and to evaluate the efficacy and tolerability of three different dosages of HP-ß-CD in patients with NPC1 after long-term treatment. Twelve patients aged at least 2 years (2-39 years of age) with a confirmed diagnosis of NPC1 were randomized to receive one of three IV doses of HP-ß-CD (1500 mg/kg, 2000 mg/kg, or 2500 mg/kg) every 2 weeks for 48 weeks. All patients received HP-ß-CD; there was no placebo or other control. PK testing of plasma and cerebrospinal fluid (CSF) was at set times after the first infusion. Pharmacodynamic assessments included biomarkers of cholesterol metabolism (synthesis and breakdown products), N-palmitoyl-O-phosphocholineserine (PPCS), and specific biomarkers of CSF neurodegeneration (including total Tau), CNS inflammation (glial fibrillary acidic protein [GFAP] and tumor necrosis factor α [TNFα]), CNS cholesterol metabolism (24S-hydroxycholesterol) and inflammatory markers. Efficacy measures included clinical disease severity, neurologic symptoms, and clinical impressions of improvement. Safety assessment included physical examination, vital signs, clinical safety laboratory assessment and adverse events (AEs). Results: Nine patients completed the study, 2 in the 1500 mg/kg group, 4 in the 2000 mg/kg group and 3 in the 2500 mg/kg group. Three patients (all in the 1500 mg/kg group) discontinued the study because of either physician decision/site Principal Investigator (PI) discretion, withdrawal by subject/patient/parent/guardian, or other non-safety reasons. In 5 patients who underwent serial lumbar punctures, HP-ß-CD was detected in the CSF. Of the 9 patients who completed the study, 8 (88.9%) improved in at least two domains of the 17-Domain Niemann-Pick disease Type C-Clinical Severity Scale (17D-NPC-CSS), and 6 of these patients improved in at least one domain viewed by patients and their caregivers to be key to quality of life, namely, speech, swallow, fine and gross motor skills, and cognition. Of the 9 patients who completed the study, 7 were viewed by their treating physicians as having improved to some degree at the end of the study, and 2 remained stable; both outcomes are highly relevant in a progressive neurodegenerative disease. Some patients and families reported improvement in quality of life.All three doses of HP-ß-CD were well tolerated overall, with most treatment-emergent adverse events transient, mild-to-moderate in nature, and considered by the site PIs to be not related to study drug. Interpretation: This 48-week trial is the longest to date to evaluate the safety, tolerability, and efficacy across multiple clinical endpoints of IV administration of Trappsol® Cyclo™ (HP-ß-CD) in NPC1 patients. In pediatric and adult patients with NPC, Trappsol® Cyclo™ IV improved clinical signs and symptoms and was generally well tolerated. The findings presented here demonstrate a favorable benefit-risk profile and support the global pivotal trial now underway to evaluate the long-term treatment benefits and the potential of Trappsol® Cyclo™ as a disease-modifying treatment in this patient population.

Hereditary orotic aciduria identified by newborn screening.

Introduction: Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria. Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill. Methods: Measuring orotic acid as part of expanded newborn screening using flow injection analysis tandem mass spectrometry. Results: Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened. The screen has identified ten Muslim Arab newborns that remain asymptomatic so far, with DBS orotic acid elevated up to 10 times the upper reference limit. Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the UMPS gene. Conclusion: Newborn screening measuring of orotic acid, now integrated into the routine tandem mass spectrometry panel, is capable of identifying neonates with hereditary orotic aciduria.

Hyperinsulinism/hyperammonemia syndrome caused by biallelic SLC25A36 mutation.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome has been known to be caused by dominant gain-of-function mutations in GLUD1, encoding the mitochondrial enzyme glutamate dehydrogenase. Pathogenic GLUD1 mutations enhance enzymatic activity by reducing its sensitivity to allosteric inhibition by GTP. Two recent independent studies showed that a similar HI/HA phenotype can be caused by biallelic mutations in SLC25A36, encoding pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine and guanine nucleotides across the inner mitochondrial membrane: one study reported a single case caused by a homozygous truncating mutation in SLC25A36 resulting in lack of expression of SLC25A36 in patients' fibroblasts. A second study described two siblings with a splice site mutation in SLC25A36, causing reduction of mitochondrial GTP content, putatively leading to hyperactivation of glutamate dehydrogenase. In an independent study, through combined linkage analysis and exome sequencing, we demonstrate in four individuals of two Bedouin Israeli related families the same disease-causing SLC25A36 (NM_018155.3) c.284 + 3A > T homozygous splice-site mutation found in the two siblings. We demonstrate that the mutation, while causing skipping of exon 3, does not abrogate expression of mRNA and protein of the mutant SLC25A36 in patients' blood and fibroblasts. Affected individuals had hyperinsulinism, hyperammonemia, borderline low birth weight, tonic-clonic seizures commencing around 6 months of age, yet normal intellect and no significant other morbidities. Chronic constipation, hypothyroidism, and developmental delay previously described in a single patient were not found. We thus verify that biallelic SLC25A36 mutations indeed cause HI/HA syndrome and clearly delineate the disease phenotype.

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.

Characterization of pregnancy outcome of women with an offspring with inborn errors of metabolism: A population-based study.

Introduction: Inborn errors of metabolism (IEM) are scarce, and their diagnosis is often made after birth. This has led to the perception that most fetuses affected by these disorders do not become clinically apparent during pregnancy. Our aim was to determine the obstetrical characteristics of women with an offspring affected by IEM. Methods: This population-based retrospective cohort study included all women who delivered at the Soroka University Medical Center (SUMC) from 1988 to 2017 who met the inclusion criteria. Mothers who had an offspring with IEM were included in the study group, and those who had offsprings without IEM comprised the comparison group. Results: A total of 388,813 pregnancies were included in the study, and 184 of them were complicated by a fetus with IEM. The number of Bedouin women was higher in the IEM-affected infant group than in the comparison group (90.8% vs. 53.3%, p < 0.001); women who had a fetus with IEM had a higher rate of polyhydramnios (7.1% vs. 3.2%, p = 0.005), HELLP syndrome (3.3% vs. 1.1%, p = 0.014), and preterm birth (20.7% vs. 10.1%, p < 0.001); neonates with IEM had lower mean birth weight (p < 0.001), lower Apgar scores at 1' and 5' minutes (p < 0.001), and a higher rate of fetal growth restriction (FGR) (p < 0.001), postpartum death <28 days (p < 0.001), and neonatal death (p < 0.001) than those in the comparison group. Pregnancies with IEM fetuses were independently associated with preterm birth (OR 2.00; CI 1.4-3), polyhydramnios (OR 2.08; CI 1.17-3.71), and FGR (OR 2.24; CI 1.2-4.19). Each family of metabolic diseases is independently associated with specific pregnancy complications (i.e., mitochondrial diseases are associated with HELLP syndrome (OR 5.6; CI 1.8-17), and lysosomal storage disease are associated with nonimmune hydrops fetalis (OR 26.4; CI 3.39-206). Conclusion: This study reports for the first time, an independent association of IEM with specific complications of pregnancy. This observation has clinical implications, as the identification of specific pregnancy complications in a population at risk for IEM can assist in the prenatal diagnosis of an affected fetus.

Elevated Alpha-Fetoprotein in Infantile-Onset Niemann-Pick Type C Disease with Liver Involvement.

Niemann-Pick disease type C (NPC) is a rare autosomal recessive neuro-visceral lipid storage disease. We describe nine cases of infantile-onset NPC with various genetic mutations in the NPC1 gene, which presented with neonatal cholestasis. Serum alpha-fetoprotein (AFP) levels were obtained as part of their workup during the first four months of life. In eight of nine (89%) patients, serum AFP demonstrated elevated levels. Seven infants displayed marked elevations, ranging from 4 to 300 times the upper limit for age-adjusted norms. In most patients, AFP levels peaked during the initial test and declined over time as cholestasis resolved. We conclude that elevated AFP levels are a common, although non-specific, marker for NPC-associated liver disease. These findings demonstrate the benefit of including AFP levels in the workup of neonatal liver disease, especially if there is accompanied cholestasis and if NPC is suspected.

Refining the Phenotypic Spectrum of KMT5B-Associated Developmental Delay.

The role of lysine methyltransferases (KMTs) and demethylases (KDMs) in the regulation of chromatin modification is well-established. Recently, deleterious heterozygous variants in KMT5B were implicated in individuals with intellectual disability (ID) and/or autism spectrum disorder. We describe three unrelated patients with global developmental delay (GDD) or ID, macrocephaly and additional features. Using whole exome sequencing, each of the probands was found to harbor a distinct de novo heterozygous disease-causing variant in KMT5B: c.541C > G (p.His181Asp); c.833A > T (p.Asn278Ile); or c.391_394delAAAG (p.Lys131GlufsTer6). We discuss herein their clinical presentations, and compare them to those of previously reported patients. Furthermore, using a three-dimensional computational model of the KMT5B protein, we demonstrate the predicted structural effects of the two missense variants. Our findings support the role of de novo missense and nonsense variants in KMT5B-associated GDD/ID, and suggest that this gene should be considered in the differential diagnosis of neurodevelopmental disorders accompanied by macrocephaly and/or overgrowth.

What Can We Learn from the Parents of Children Affected with Mucopolysaccharidosis Type III-A in Israel?

Sanfilippo Syndrome, or mucopolysaccharidosis type III (MPS III), is a group of autosomal-recessive lysosomal storage disorders leading to tissue accumulation of heparan sulfate. MPS III is caused by deficiency in one of 4 enzymes involved in lysosomal degradation of heparan sulfate. Based on the relevant enzyme deficiency, 4 types have been recognized. MPS III constitutes a progressive neurodegenerative and systemic disorder. Parents of children diagnosed with MPS III were interviewed using a retrospective questionnaire based on the known clinical manifestations of MPS III. Eight patients from 4 unrelated families of varied ethnic origin were included. All children were diagnosed with MPS type III-A. Average age at diagnosis was 6.1 years. The most common early clinical manifestations leading to parental suspicion of illness were speech delay and coarse facial features. All children were reported to have global developmental delay, sleep disorders, recurrent infections, hyperactivity, and decreased hearing. The time from first medical inquiry until diagnosis was over 2 years on average, consistent with the delay in diagnosis described in the literature. MPS III children frequently undergo early and repeated ear, nose and throat surgeries, thus we suggest that a high index of suspicion is warranted in relevant clinical circumstances.

Whole-exome sequencing reveals a monogenic cause in 56% of individuals with laterality disorders and associated congenital heart defects.

BACKGROUND: The molecular basis of heterotaxy and congenital heart malformations associated with disruption of left-right asymmetry is broad and heterogenous, with over 25 genes implicated in its pathogenesis thus far. OBJECTIVE: We sought to elucidate the molecular basis of laterality disorders and associated congenital heart defects in a cohort of 30 unrelated probands of Arab-Muslim descent, using next-generation sequencing techniques. METHODS: Detailed clinical phenotyping followed by whole-exome sequencing (WES) was pursued for each of the probands and their parents (when available). Sanger sequencing was used for segregation analysis of disease-causing mutations in the families. RESULTS: Using WES, we reached a molecular diagnosis for 17 of the 30 probands (56.7%). Genes known to be associated with heterotaxy and/or primary ciliary dyskinesia, in which homozygous pathogenic or likely pathogenic variants were detected, included CFAP53 (CCDC11), CFAP298 (C21orf59), CFAP300, LRRC6, GDF1, DNAAF1, DNAH5, CCDC39, CCDC40, PKD1L1 and TTC25. Additionally, we detected a homozygous disease causing mutation in DAND5, as a novel recessive monogenic cause for heterotaxy in humans. Three additional probands were found to harbour variants of uncertain significance. These included variants in DNAH6, HYDIN, CELSR1 and CFAP46. CONCLUSIONS: Our findings contribute to the current knowledge regarding monogenic causes of heterotaxy and its associated congenital heart defects and underscore the role of next-generation sequencing techniques in the diagnostic workup of such patients, and especially among consanguineous families.

Predictors of Developmental and Respiratory Outcomes Among Preterm Infants With Bronchopulmonary Dysplasia.

Objectives: To examine the importance of perinatal and postnatal environmental factors on developmental and respiratory outcomes among preterm infants with bronchopulmonary dysplasia (BPD). Methods: Preterm infants (<32 weeks of gestation) born at a single tertiary medical center between 2012 and 2015 were included. Development was assessed at 12 months corrected age. Parents retrospectively completed a health and lifestyle questionnaire reviewing their child's health during the first 2 years of life. A linear regression model was applied to assess the effect of various perinatal and postnatal factors on development. A machine-learning algorithm was trained to assess factors affecting inhaler use. Results: Of 398 infants meeting the inclusion criteria, 208 qualified for the study: 152 (73.1%) with no BPD, 40 (19.2%) with mild BPD, and 16 (7.7%) with moderate-severe BPD. Those in the moderate-severe group were more likely to be male, have mothers who were less educated, and require longer ventilation periods and less time to regain birth weight. They were also more likely to have mothers with asthma/allergies and to have a parent who smoked. Those in the moderate-severe BPD group exhibited significantly lower developmental scores (85.2 ± 16.4) than the no-BPD group (99.3 ± 10.9) and the mild BPD group (97.8 ± 11.7, p < 0.008) as well as more frequent inhaler use (p = 0.0014) than those with no or mild BPD. In addition to perinatal factors, exposure to breast milk, income level and daycare attendance positively affected development. Exposure to cigarette smoke, allergies among family members and daycare attendance proved to be important factors in inhaler use frequency. Conclusions: Postnatal environmental factors are important in predicting and modifying early childhood outcomes among preterm infants.

The Effects of a Ketogenic Diet on Patients with Dihydrolipoamide Dehydrogenase Deficiency.

BACKGROUND: Dihydrolipoamide dehydrogenase (DLD lipoamide dehydrogenase, the E3 subunit of the pyruvate dehydrogenase complex (PDHC)) is the third catalytic enzyme of the PDHC, which converts pyruvate to acetyl-CoA catalyzed with the introduction of acetyl-CoA to the tricyclic acid (TCA) cycle. In humans, PDHC plays an important role in maintaining glycose homeostasis in an aerobic, energy-generating process. Inherited DLD-E3 deficiency, caused by the pathogenic variants in DLD, leads to variable presentations and courses of illness, ranging from myopathy, recurrent episodes of liver disease and vomiting, to Leigh disease and early death. Currently, there is no consensus on treatment guidelines, although one suggested solution is a ketogenic diet (KD). OBJECTIVE: To describe the use and effects of KD in patients with DLD-E3 deficiency, compared to the standard treatment. RESULTS: Sixteen patients were included. Of these, eight were from a historical cohort, and of the other eight, four were on a partial KD. All patients were homozygous for the D479V (or D444V, which corresponds to the mutated mature protein without the mitochondrial targeting sequence) pathogenic variant in DLD. The treatment with partial KD was found to improve patient survival. However, compared to a historical cohort, the patients' quality of life (QOL) was not significantly improved. CONCLUSIONS: The use of KD offers an advantage regarding survival; however, there is no significant improvement in QOL.

The effects of the COVID-19 pandemic on patients with lysosomal storage disorders in Israel.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is the causative agent of the current COVID-19 pandemic. Lysosomal storage disorders (LSD) comprise of 70 inherited inborn errors of metabolism. Affected individuals suffer from multi-systemic involvement with variable severity and rate of disease progression between different diseases. Some of the LSDs have established treatments, whether parenteral or oral therapies. The full impact of the COVID-19 pandemic together with the lockdown on the wellbeing and medical management of patients with rare diseases, such as LSDs, is widely unknown. Herein, we describe the effects of the COVID-19 pandemic and its associated mandatory home lockdown on patients with LSDs in Israel. RESULTS: We present a prospective multi-center questionnaire study including 48 LSD patients from four medical centers in Israel. The study objective was to assess the impact of the COVID-19 pandemic restrictions on individuals with LSDs in Israel, as reported by their caregivers. Secondary objectives were to assess the morbidity from SARS CoV-2 in LSD patients and the impact of changes in mood and behavior on compliance to treatment and to assess the relationship between changes in mood to changes in cognition and behavior. Thirty one of 38 patients (82%) who received any kind of regular treatment did not miss treatments. Among patients receiving enzyme replacement therapy (ERT) in the in-hospital setting, 5 patients (20%) experienced treatment disruptions. Four patients had tested positive for SARS-Cov-2 virus infection by PCR. Seven out of the 48 patients (14%) described mood changes with cognitive and motor deterioration during the home quarantine. CONCLUSIONS: We observed high rates of treatment adherence and low morbidity through the COVID-19 pandemic in patients with LSDs in Israel. LSDs patients can be a model for patients with complex chronic diseases requiring routine treatments and surveillance during a pandemic or other disruption of daily routine.

Multiple Acyl-CoA Dehydrogenase Deficiency with Variable Presentation Due to a Homozygous Mutation in a Bedouin Tribe.

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a fatty acid and amino acid oxidation defect caused by a deficiency of the electron-transfer flavoprotein (ETF) or the electron-transfer flavoprotein dehydrogenase (ETFDH). There are three phenotypes of the disease, two neonatal forms and one late-onset. Previous studies have suggested that there is a phenotype-genotype correlation. We report on six patients from a single Bedouin tribe, five of whom were sequenced and found to be homozygous to the same variant in the ETFDH gene, with variable severity and age of presentation. The variant, NM_004453.3 (ETFDH): c.524G>A, p.(R175H), was previously recognized as pathogenic, although it has not been reported in the literature in a homozygous state before. R175H is located near the FAD binding site, likely affecting the affinity of FAD for EFT:QO. The single homozygous ETFDH pathogenic variant was found to be causing MADD in this cohort with an unexpectedly variable severity of presentation. The difference in severity could partly be explained by early diagnosis via newborn screening and early treatment with the FAD precursor riboflavin, highlighting the importance of early detection by newborn screening.

Deep intronic variant in the ARSB gene as the genetic cause for Maroteaux-Lamy syndrome (MPS VI).

Maroteaux-Lamy syndrome (MPS-VI) is a rare autosomal-recessive disorder with a wide spectrum of clinical manifestations, ranging from an attenuated to a rapidly progressive disease. It is caused by variants in ARSB, which encodes the lysosomal arylsulfatase B (ARSB) enzyme, part of the degradation process of glycosaminoglycans in lysosomes. Over 220 variants have been reported so far, with a majority of missense variants. We hereby report two siblings of Bedouin origin with a diagnosis of MPS-VI. Western blots in patient fibroblasts revealed total absence of ARSB protein production. Complete sequencing of the coding region of ARSB did not identify a candidate disease-associated variant. However, deep sequencing of the noncoding region of ARSB by whole genome sequencing (WGS) revealed a c.1142+581A to G variant. The variant is located within intron 5 and fully segregated with the disease in the family. Determination of the genetic cause for these patients enabled targeted treatment by enzyme replacement therapy, along with appropriate genetic counseling and prenatal diagnosis for the family. These results highlight the advantage of WGS as a powerful tool, for improving the diagnostic rate of rare disease-causing variants, and emphasize the importance of studying deep intronic sequence variation as a cause of monogenic disorders.

Nonhepatic hyperammonemic encephalopathy complications following bariatric surgery: a case report and review of the literature.

BACKGROUND: Hyperammonemic encephalopathy, a rare but fatal condition, is increasingly being reported as a possible complication of bariatric surgery. Here, we present a case of hyperammonemic encephalopathy, focusing on the clinical presentation, diagnostic measures, and our treatment methods, which resulted in a rare favorable outcome, emphasizing the unique role of renal replacement treatment. We also provide a detailed discussion of the mechanism through which hyperammonemia occurs secondarily to bariatric surgery. CASE PRESENTATION: A 44-year-old Moroccan Jew woman with a history of obesity presented in the hospital with urea cycle disorder that manifested after bariatric surgery. A rapid diagnostic process, together with conservative treatment with lactulose, nutritional supplementation, dietary protein restriction, and ammonia scavengers did not result in adequate improvement. Therefore, hemofiltration was performed, which yielded a favorable outcome. CONCLUSIONS: The case findings indicate an association between hyperammonemic encephalopathy and bariatric surgery, and support early treatment with ammonia scavengers, as currently accepted. Nevertheless, if rapid improvement is not seen, it is advisable to consider hemodialysis or hemofiltration as early invasive strategies.

Maternal anemia and offspring failure to thrive - results from a large population-based cohort.

OBJECTIVE: To evaluate whether an association exists between maternal anemia and offspring failure to thrive (FTT) during childhood. METHODS: A population-based cohort analysis was performed, comparing the risk for FTT among children (up to 18 years old) based on maternal hemoglobin (Hb) levels, upon postpartum discharge. Maternal Hb levels were categorized into 3 levels: <9.0 (moderate-severe anemia), 9.0-11.0 (mild anemia), and ≥11.0 g/dL (no anemia). FTT diagnosis was based on hospital records. All singletons born between 1991 and 2014 and discharged alive without congenital malformations were included. A survival curve was constructed to compare the cumulative FTT incidence, and a Weibull parametric survival analysis to assess the independent association between maternal anemia and offspring FTT while controlling for confounders. RESULTS: Of the 214,305 included deliveries, 22,071 parturients (10.3%) were discharged with Hb <9.00; 83,932 (39.2%) with Hb between 9.0-11.0; and 108,302 (50.5%) with Hb ≥11.0 g/dL. FTT rates were 1.3% (n = 287), 1.2% (n = 967), and 1.1% (n = 1141) in the same groups, respectively (p = .003). The survival curve demonstrated a significantly higher cumulative incidence of FTT diagnosis in the moderate-severe maternal anemia group (p < .001). In the Weibull analysis, constructed for newborns with appropriate birthweight, both groups of maternal anemia were found to be independently associated with FTT related hospitalizations (mild anemia aHR, 1.1; 95%CI 1.002-1.219; p = .045, moderate-severe anemia aHR, 1.321; 95%CI, 1.141-1.529; p < .001). CONCLUSION: Maternal anemia is independently associated with long-term FTT in offspring, with increasing FTT rates proportional to anemia severity.