Quality of life in children with erythropoietic protoporphyria: a case-control study.

Erythropoietic protoporphyria (EPP) is an inherited metabolic disease that causes painful phototoxic reactions, starting in childhood. Studies have shown a reduced quality of life (QoL) in adults with EPP, however, data on children with the disease are lacking. Since treatment for EPP is currently not registered for children, knowledge about their QoL is of crucial importance. In this prospective, case-control study, we included children from the Netherlands and Belgium diagnosed with EPP and matched to healthy controls. Previously collected EPP quality of life (EPP-QoL) data from matched adults with EPP were used. QoL scores, utilizing the Pediatric Quality of Life Inventory (PedsQL) and the disease-specific EPP-QoL, were collected. Scores range from 0 to 100, with higher scores indicating a higher QoL. Non-parametric tests were used to compare groups. A total of 15 cases, 13 matched healthy control children, and 15 matched adults with EPP were included. Children with EPP exhibited lower median scores in the PedsQL in both physical (cases: 87.5 (interquartile range [IQR] 77.7-96.1), controls: 99.2 [IQR 94.9-100.0], p = 0.03) and social (cases: 77.5 [IQR 69.4-86.3], controls: 97.5 [IQR 78.8-100.0], p = 0.04) domains compared to healthy children, although these differences were not statistically significant after correcting for multiple testing. The overall median EPP-QoL score for children was similar to adults with EPP (children: 44.4 [IQR 25.0-54.2], adults: 45.8 [IQR 25.7-68.1], p = 0.68). However, within the EPP-QoL subdomain on QoL, children were found to have significantly lower median scores (children: 16.7 [IQR 0.0-33.3], adults: 33.3 [IQR 33.3-62.5], p < 0.01). In conclusion, children with EPP experience a reduced QoL compared to both healthy children and adults with EPP. Ensuring treatment availability for this patient group is crucial for improving their QoL. We advocate the inclusion of children in safety and efficacy studies, to ensure availability of treatment in the future.

5,10-methenyltetrahydrofolate synthetase deficiency: An extreme rare defect of folate metabolism in two Dutch siblings.

Two siblings, presenting with a neurometabolic phenotype, were identified with 5, 10-methenyltetrahydrofolate synthetase (MTHFS) deficiency. Whole genome sequencing in both patients demonstrated an homozygous MTHFS variant NM_006441.3(MTHFS):c.434G > A, p.Arg145Gin, which has been described before. At baseline, both patients showed moderate hyperhomocysteinemia, decreased 5-methyltetrahydrofolate (5MTHF), and increased 5-formyltetrahydrofolate (5-FTHF) in whole blood. In CSF, 5MTHF levels were in the low-normal range and 5-FTHF was strongly increased. In our novel enzyme assay, MTHFS activity was deficient in cultured fibroblasts in both sisters. Oral treatment was initiated with escalating dose of 5-methyltetrahydrofolate (5MTHF) up to 12 mg and hydroxycobalamin 5 mg daily. Plasma homocysteine normalized and 5MTHF became elevated in the blood of both patients. The elevated 5FTHF levels increased further on treatment in blood and CSF. This regimen resulted in some clinical improvement of patient 1. In patient 2, the clinical benefits of 5MTHF supplementation were less obvious. It seems plausible that the alleviation of the deficient 5MTHF levels and normalization of homocysteine in blood are of some clinical benefit. On the other hand, the very high levels of 5FTHF may well be detrimental and may prompt us to decrease the dose of 5MTHF. In addition, we hypothesize that the crippled MTHFS enzyme may destabilize the purinosome, which is presumably not ameliorated by 5MTHF.

A Delphi Survey Study to Formulate Statements on the Treatability of Inherited Metabolic Disorders to Decide on Eligibility for Newborn Screening.

The Wilson and Jungner (W&J) and Andermann criteria are meant to help select diseases eligible for population-based screening. With the introduction of next-generation sequencing (NGS) methods for newborn screening (NBS), more inherited metabolic diseases (IMDs) can technically be included, and a revision of the criteria was attempted. This study aimed to formulate statements and investigate whether those statements could elaborate on the criterion of treatability for IMDs to decide on eligibility for NBS. An online Delphi study was started among a panel of Dutch IMD experts (EPs). EPs evaluated, amended, and approved statements on treatability that were subsequently applied to 10 IMDs. After two rounds of Delphi, consensus was reached on 10 statements. Application of these statements selected 5 out of 10 IMDs proposed for this study as eligible for NBS, including 3 IMDs in the current Dutch NBS. The statement: 'The expected benefit/burden ratio of early treatment is positive and results in a significant health outcome' contributed most to decision-making. Our Delphi study resulted in 10 statements that can help to decide on eligibility for inclusion in NBS based on treatability, also showing that other criteria could be handled in a comparable way. Validation of the statements is required before these can be applied as guidance to authorities.

Are Anti-rhGAA Antibodies a Determinant of Treatment Outcome in Adults with Late-Onset Pompe Disease? A Systematic Review.

BACKGROUND: Pompe disease is a lysosomal storage disease characterised by skeletal and respiratory muscle weakness. Since 2006, enzyme replacement therapy (ERT) with alglucosidase alfa has been available. ERT significantly improves the prognosis of patients with Pompe disease. The effect of high antibody titres on treatment response in adults with late-onset Pompe disease (LOPD) remains unclear but may contribute to interpatient variation. We therefore conducted a systematic review on this subject. METHODS: A systematic search was performed in Embase, Medline Ovid, Web of Science, Psych Info Ovid, Cochrane (Clinical Trials only), and Google Scholar (random top-200). Articles were included if they involved adults with LOPD treated with alglucosidase alfa and mentioned anti-rhGAA antibodies or antibody titres. In addition, articles mentioning dosages different from the standard recommended dosage were included. RESULTS: Our literature search retrieved 2562 publications, and 17 fulfilled our selection criteria, describing 443 cases. Seven publications reported on anti-rhGAA antibody titres on a group level, with the percentage of patients with a high titre as defined in the included articles ranging from 0-33%. Six publications reported on the effect of anti-rhGAA antibody titre on clinical course, and four found no correlation. Two studies reported a negative effect on treatment. The first study found a greater improvement in Medical Research Council (MRC) score in patients with no detectable antibody titre. In the second study, a patient discontinued ERT due to a declining neuromuscular state as a result of high anti-rhGAA antibody titres. Seven publications reported on 17 individual patients with a high antibody titre (range 1:12,800-1:3,906,250). In only two cases were high-sustained neutralising antibodies reported to interfere with treatment efficacy. CONCLUSIONS: No clear effect of anti-rhGAA IgG antibodies on treatment response could be established for the majority of LOPD patients with a high antibody titre. In a minority of patients, a clinical decline related to (possible) interference of anti-rhGAA antibodies was described.

Newborn screening for primary carnitine deficiency: who will benefit? - a retrospective cohort study.

BACKGROUND: Newborn screening (NBS) programmes identify a wide range of disease phenotypes, which raises the question whether early identification and treatment is beneficial for all. This study aims to answer this question for primary carnitine deficiency (PCD) taking into account that NBS for PCD identifies newborns with PCD and also until then undiagnosed mothers. METHODS: We investigated clinical, genetic (variants in SLC22A5 gene) and functional (carnitine transport activity in fibroblasts) characteristics of all referred individuals through NBS (newborns and mothers) and clinically diagnosed patients with PCD (not through NBS). Disease phenotype in newborns was predicted using data from PCD mothers and cases published in literature with identical SLC22A5 variants. RESULTS: PCD was confirmed in 19/131 referred newborns, 37/82 referred mothers and 5 clinically diagnosed patients. Severe symptoms were observed in all clinically diagnosed patients, 1 newborn and none of the mothers identified by NBS. PCD was classified as severe in all 5 clinically diagnosed patients, 3/19 newborns and 1/37 mothers; as benign in 8/19 newborns and 36/37 mothers and as unknown in 8/19 newborns. Carnitine transport activity completely separated severe phenotype from benign phenotype (median (range): 4.0% (3.5-5.0)] vs 26% (9.5-42.5), respectively). CONCLUSION: The majority of mothers and a significant proportion of newborns with PCD identified through NBS are likely to remain asymptomatic without early treatment. Conversely, a small proportion of newborns with predicted severe PCD could greatly benefit from early treatment. Genetic variants and carnitine transport activity can be used to distinguish between these groups.

Home-Based Infusion of Alglucosidase Alfa Can Safely be Implemented in Adults with Late-Onset Pompe Disease: Lessons Learned from 18,380 Infusions.

BACKGROUND: Enzyme replacement therapy (ERT) with alglucosidase alfa is the treatment for patients with Pompe disease, a hereditary metabolic myopathy. Home-based ERT is unavailable in many countries because of the boxed warning alglucosidase alfa received due to the risk of infusion-associated reactions (IARs). Since 2008, home infusions have been provided in The Netherlands. OBJECTIVES: This study aimed to provide an overview of our experience with home-based infusions with alglucosidase alfa in adult Pompe patients, focusing on safety, including management of IARs. METHOD: We analysed infusion data and IARs from adult patients starting ERT between 1999 and 2018. ERT was initially given in the hospital during the first year. Patients were eligible for home treatment if they were without IARs for multiple consecutive infusions and if a trained home nurse, with on-call back-up by a doctor, was available. The healthcare providers graded IARs. RESULTS: We analysed data on 18,380 infusions with alglucosidase alfa in 121 adult patients; 4961 infusions (27.0%) were given in hospital and 13,419 (73.0%) were given at home. IARs occurred in 144 (2.9%) hospital infusions and 113 (0.8%) home infusions; 115 (79.9% of 144) IARs in hospital and 104 (92.0% of 113) IARs at home were mild, 25 IARs (17.4%) in hospital and 8 IARs (7.1%) at home were moderate, and very few severe IARs occurred (4 IARs in hospital [2.8%] and 1 IAR at home [0.9%]). Only one IAR in the home situation required immediate clinical evaluation in the hospital. CONCLUSION: Given the small numbers of IARs that occurred with the home infusions, of which only one was severe, we conclude that alglucosidase alfa can be administered safely in the home situation, provided the appropriate infrastructure is present.

Home-based enzyme replacement therapy in children and adults with Pompe disease; a prospective study.

BACKGROUND: Pompe disease is a lysosomal storage disease treated with life-long enzyme replacement therapy (ERT). Home-based ERT has been provided in the Netherlands since 2008 because it diminishes the burden of treatment, increases patient flexibility and autonomy, and is thus a more patient-centred approach to ERT. METHODS: All Dutch Pompe patients receiving alglucosidase alfa infusions at home were approached to participate in a questionnaire to validate the safety of home-based ERT. Prospective data on symptoms occurring during or within 48 h after infusion and retrospective data on infusion associated reactions (IARs) in the last three months were collected four times during one year. RESULTS: In total, 116 out of 120 eligible patients (17 classic infantile, 2 atypical infantile, 15 childhood onset and 82 adult) filled out 423 questionnaires (response rate: 88.1%). Symptoms during or after infusion were reported 27 times in 17 patients. Fatigue was the most commonly reported health complaint (in 9.5% of patients). Four health complaints were judged to be IARs and reported to the Erasmus MC University Medical Center. None of the IARs reported in this study warranted emergency clinical care. CONCLUSIONS: Our data demonstrate that home-based ERT in Pompe disease can be safely implemented as few, mostly mild, symptoms were reported during or after infusion. Insights from this study can be used as a base for implementing home-based ERT in other countries and to further optimize patient care, as unreported mild symptoms do not pose a health risk but may still be relevant to the patient.

Web-accessible application for identifying pathogenic transcripts with RNA-seq: Increased sensitivity in diagnosis of neurodevelopmental disorders.

For neurodevelopmental disorders (NDDs), a molecular diagnosis is key for management, predicting outcome, and counseling. Often, routine DNA-based tests fail to establish a genetic diagnosis in NDDs. Transcriptome analysis (RNA sequencing [RNA-seq]) promises to improve the diagnostic yield but has not been applied to NDDs in routine diagnostics. Here, we explored the diagnostic potential of RNA-seq in 96 individuals including 67 undiagnosed subjects with NDDs. We performed RNA-seq on single individuals' cultured skin fibroblasts, with and without cycloheximide treatment, and used modified OUTRIDER Z scores to detect gene expression outliers and mis-splicing by exonic and intronic outliers. Analysis was performed by a user-friendly web application, and candidate pathogenic transcriptional events were confirmed by secondary assays. We identified intragenic deletions, monoallelic expression, and pseudoexonic insertions but also synonymous and non-synonymous variants with deleterious effects on transcription, increasing the diagnostic yield for NDDs by 13%. We found that cycloheximide treatment and exonic/intronic Z score analysis increased detection and resolution of aberrant splicing. Importantly, in one individual mis-splicing was found in a candidate gene nearly matching the individual's specific phenotype. However, pathogenic splicing occurred in another neuronal-expressed gene and provided a molecular diagnosis, stressing the need to customize RNA-seq. Lastly, our web browser application allowed custom analysis settings that facilitate diagnostic application and ranked pathogenic transcripts as top candidates. Our results demonstrate that RNA-seq is a complementary method in the genomic diagnosis of NDDs and, by providing accessible analysis with improved sensitivity, our transcriptome analysis approach facilitates wider implementation of RNA-seq in routine genome diagnostics.

Newborn screening for Cerebrotendinous Xanthomatosis: A retrospective biomarker study using both flow-injection and UPLC-MS/MS analysis in 20,000 newborns.

BACKGROUND AND AIMS: Cerebrotendinous Xanthomatosis (CTX) is a treatable disorder of bile acid synthesis caused by deficiency of 27-sterol hydroxylase -encoded by CYP27A1- leading to gastrointestinal and progressive neuropsychiatric symptoms. Biochemically, CTX is characterized by accumulation of the bile alcohol cholestanetetrol glucuronide (GlcA-tetrol) and the deficiency of tauro-chenodeoxycholic acid (t-CDCA) and tauro-trihydroxycholestanoic acid (t-THCA). MATERIALS AND METHODS: To ascertain the feasibility of CTX newborn screening (NBS) we performed a study with deidentified Dutch dried blood spots using reagents and equipment that is frequently used in NBS laboratories. 20,076 deidentified newborn blood spots were subjected to flow-injection (FIA)-MS/MS and UPLC-MS/MS analysis to determine the concentration of GlcA-tetrol and calculate the GlcA-tetrol/t-CDCA and t-THCA/GlcA-tetrol ratios. RESULTS: Using UPLC-MS/MS analysis both GlcA-tetrol concentration and/or metabolite ratios GlcA-tetrol/t-CDCA proved to be informative biomarkers; newborn DBS results did not overlap with those of the CTX patients. For FIA-MS/MS, GlcA-tetrol also was an excellent marker but when using the combination of the GlcA-tetrol/t-CDCA and t-THCA/GlcA-tetrol ratios also did not yield any screen positives. CONCLUSION: Newborn screening for CTX using only metabolite ratios following the measurement of three CTX biomarkers is possible using either FIA-MS/MS or UPLC-MS/MS, which paves the way for introduction of CTX NBS.

Multi-omics in classical galactosemia: Evidence for the involvement of multiple metabolic pathways.

Classical galactosemia (CG) is one of the more frequent inborn errors of metabolism affecting approximately 1:40.000 people. Despite a life-saving galactose-restricted diet, patients develop highly variable long-term complications including intellectual disability and movement disorders. The pathophysiology of these complications is still poorly understood and development of new therapies is hampered by a lack of valid prognostic biomarkers. Multi-omics approaches may discover new biomarkers and improve prediction of patient outcome. In the current study, (semi-)targeted mass-spectrometry based metabolomics and lipidomics were performed in erythrocytes of 40 patients with both classical and variant phenotypes and 39 controls. Lipidomics did not show any significant changes or deficiencies. The metabolomics analysis revealed that CG does not only compromise the Leloir pathway, but also involves other metabolic pathways including glycolysis, the pentose phosphate pathway, and nucleotide metabolism in the erythrocyte. Moreover, the energy status of the cell appears to be compromised, with significantly decreased levels of ATP and ADP. This possibly is the consequence of two different mechanisms: impaired formation of ATP from ADP possibly due to reduced flux though the glycolytic pathway and trapping of phosphate in galactose-1-phosphate (Gal-1P) which accumulates in CG. Our findings are in line with the current notion that the accumulation of Gal-1P plays a key role in the pathophysiology of CG not only by depletion of intracellular phosphate levels but also by decreasing metabolite abundance downstream in the glycolytic pathway and affecting other pathways. New therapeutic options for CG could be directed towards the restoration of intracellular phosphate homeostasis.

Integration of metabolomics with genomics: Metabolic gene prioritization using metabolomics data and genomic variant (CADD) scores.

The integration of metabolomics data with sequencing data is a key step towards improving the diagnostic process for finding the disease-causing genetic variant(s) in patients suspected of having an inborn error of metabolism (IEM). The measured metabolite levels could provide additional phenotypical evidence to elucidate the degree of pathogenicity for variants found in genes associated with metabolic processes. We present a computational approach, called Reafect, that calculates for each reaction in a metabolic pathway a score indicating whether that reaction is deficient or not. When calculating this score, Reafect takes multiple factors into account: the magnitude and sign of alterations in the metabolite levels, the reaction distances between metabolites and reactions in the pathway, and the biochemical directionality of the reactions. We applied Reafect to untargeted metabolomics data of 72 patient samples with a known IEM and found that in 81% of the cases the correct deficient enzyme was ranked within the top 5% of all considered enzyme deficiencies. Next, we integrated Reafect with Combined Annotation Dependent Depletion (CADD) scores (a measure for gene variant deleteriousness) and ranked the metabolic genes of 27 IEM patients. We observed that this integrated approach significantly improved the prioritization of the genes containing the disease-causing variant when compared with the two approaches individually. For 15/27 IEM patients the correct affected gene was ranked within the top 0.25% of the set of potentially affected genes. Together, our findings suggest that metabolomics data improves the identification of affected genes in patients suffering from IEM.

Thermo-sensitive mitochondrial trifunctional protein deficiency presenting with episodic myopathy.

Mitochondrial trifunctional protein (MTP) is involved in long-chain fatty acid ß-oxidation (lcFAO). Deficiency of one or more of the enzyme activities as catalyzed by MTP causes generalized MTP deficiency (MTPD), long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), or long-chain ketoacyl-CoA thiolase deficiency (LCKATD). When genetic variants result in thermo-sensitive enzymes, increased body temperature (e.g. fever) can reduce enzyme activity and be a risk factor for clinical decompensation. This is the first description of five patients with a thermo-sensitive MTP deficiency. Clinical and genetic information was obtained from clinical files. Measurement of LCHAD and LCKAT activities, lcFAO-flux studies and palmitate loading tests were performed in skin fibroblasts cultured at 37°C and 40°C. In all patients (four MTPD, one LCKATD), disease manifested during childhood (manifestation age: 2-10 years) with myopathic symptoms triggered by fever or exercise. In four patients, signs of retinopathy or neuropathy were present. Plasma long-chain acylcarnitines were normal or slightly increased. HADHB variants were identified (at age: 6-18 years) by whole exome sequencing or gene panel analyses. At 37°C, LCHAD and LCKAT activities were mildly impaired and lcFAO-fluxes were normal. Remarkably, enzyme activities and lcFAO-fluxes were markedly diminished at 40°C. Preventive (dietary) measures improved symptoms for most. In conclusion, all patients with thermo-sensitive MTP deficiency had a long diagnostic trajectory and both genetic and enzymatic testing were required for diagnosis. The frequent absence of characteristic acylcarnitine abnormalities poses a risk for a diagnostic delay. Given the positive treatment effects, upfront genetic screening may be beneficial to enhance early recognition.

Effect of alglucosidase alfa dosage on survival and walking ability in patients with classic infantile Pompe disease: a multicentre observational cohort study from the European Pompe Consortium.

BACKGROUND: Enzyme replacement therapy (ERT) with alglucosidase alfa has been found to improve outcomes in patients with classic infantile Pompe disease, who without treatment typically die before the age of 1 year. Variable responses to the standard recommended dosage have led to alternative dosing strategies. We aimed to assess the effect of real-world ERT regimens on survival and walking ability in these patients. METHODS: In this observational cohort study, we obtained data collected as part of a collaborative study within the European Pompe Consortium on patients with classic infantile Pompe disease from France, Germany, Italy, and the Netherlands diagnosed between Oct 26, 1998 and March 8, 2019. Eligible patients had classic infantile Pompe disease with a disease onset and proven diagnosis before age 12 months, and a hypertrophic cardiomyopathy. A proven diagnosis of classic infantile Pompe disease was defined as a confirmed deficiency of α-glucosidase in leukocytes or lymphocytes, fibroblasts or muscle, or two pathogenic GAA variants in trans, or both. We collected data on demographics, GAA variants, ERT dosage, age at death, and walking ability. We analysed the effects of ERT dosage on survival and walking ability using Cox regression, Kaplan-Meier curves, and log-rank tests. FINDINGS: We included 124 patients with classic infantile Pompe disease, of whom 116 were treated with ERT (median age at start of treatment 3·3 months [IQR 1·8-5·0, range 0·03-11·8]). During follow-up (mean duration 60·1 months [SD 57·3]; n=115), 36 (31%) of 116 patients died. 39 different ERT dosing regimens were applied. Among the 64 patients who remained on the same dosage, 16 (52%) of 31 patients on the standard dosage (20 mg/kg every other week), 12 (80%) of 15 patients on an intermediate dosage (20 mg/kg per week or 40 mg/kg every other week), and 16 (89%) of 18 patients on the high dosage (40 mg/kg per week) were alive at last follow-up. Survival was significantly improved in the high dosage group compared with the standard dosage group (hazard ratio [HR] 0·17 [95% CI 0·04-0·76], p=0·02). No significant difference in survival was identified between the intermediate dosage group and the standard dosage group (HR 0·44 [0·13-1·51], p=0·19). Of the 86 patients who reached 18 months of age, 44 (51%) learned to walk. Ten (53%) of 19 patients on the standard dosage regimen, six (67%) of nine patients on intermediate dosage regimens, and 14 (93%) of 15 patients on high dosage regimens learnt to walk, but the differences between groups were not statistically significant. INTERPRETATION: Patients with classic infantile Pompe disease treated with the high ERT dosage of 40 mg/kg per week had significantly improved survival when compared with patients treated with the standard recommended ERT dosage of 20 mg/kg every other week. Based on these results, we suggest that the currently registered dosage should be reconsidered. FUNDING: Prinses Beatrix Spierfonds and Wishdom Foundation.

Abnormal VLCADD newborn screening resembling MADD in four neonates with decreased riboflavin levels and VLCAD activity.

Early detection of congenital disorders by newborn screening (NBS) programs is essential to prevent or limit disease manifestation in affected neonates. These programs balance between the detection of the highest number of true cases and the lowest number of false-positives. In this case report, we describe four unrelated cases with a false-positive NBS result for very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD). Three neonates presented with decreased but not deficient VLCAD enzyme activity and two of them carried a single heterozygous ACADVL c.1844G>A mutation. Initial biochemical investigations after positive NBS referral in these infants revealed acylcarnitine and organic acid profiles resembling those seen in multiple acyl-CoA dehydrogenase deficiency (MADD). Genetic analysis did not reveal any pathogenic mutations in the genes encoding the electron transfer flavoprotein (ETF alpha and beta subunits) nor in ETF dehydrogenase. Subsequent further diagnostics revealed decreased levels of riboflavin in the newborns and oral riboflavin administration normalized the MADD-like biochemical profiles. During pregnancy, the mothers followed a vegan, vegetarian or lactose-free diet which probably caused alimentary riboflavin deficiency in the neonates. This report demonstrates that a secondary (alimentary) maternal riboflavin deficiency in combination with reduced VLCAD activity in the newborns can result in an abnormal VLCADD/MADD acylcarnitine profile and can cause false-positive NBS. We hypothesize that maternal riboflavin deficiency contributed to the false-positive VLCADD neonatal screening results.

Congenital disorders of glycosylation with defective fucosylation.

Fucosylation is essential for intercellular and intracellular recognition, cell-cell interaction, fertilization, and inflammatory processes. Only five types of congenital disorders of glycosylation (CDG) related to an impaired fucosylation have been described to date: FUT8-CDG, FCSK-CDG, POFUT1-CDG SLC35C1-CDG, and the only recently described GFUS-CDG. This review summarizes the clinical findings of all hitherto known 25 patients affected with those defects with regard to their pathophysiology and genotype. In addition, we describe five new patients with novel variants in the SLC35C1 gene. Furthermore, we discuss the efficacy of fucose therapy approaches within the different defects.

Managing CLN2 disease: a treatable neurodegenerative condition among other treatable early childhood epilepsies.

INTRODUCTION: Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare pediatric neurodegenerative condition, which is usually fatal by mid-adolescence. Seizures are one of the most common early symptoms of CLN2 disease, but patients often experience language deficits, movement disorders, and behavioral problems. Diagnosis of CLN2 disease is challenging (particularly when differentiating between early-onset developmental, metabolic, or epileptic syndromes), and diagnostic delays often overlap with rapid disease progression. An enzyme replacement therapy (cerliponase alfa) is now available, adding CLN2 disease to the list of potentially treatable disorders requiring a prompt diagnosis. AREAS COVERED: Although advances in enzymatic activity testing and genetic testing have facilitated diagnoses of CLN2 disease, our review highlights the presenting symptoms that are vital in directing clinicians to perform appropriate tests or seek expert opinion. We also describe common diagnostic challenges and some potential misdiagnoses that may occur during differential diagnosis. EXPERT OPINION: An awareness of CLN2 disease as a potentially treatable disorder and increased understanding of the key presenting symptoms can support selection of appropriate tests and prompt diagnosis. The available enzyme replacement therapy heralds an even greater imperative for early diagnosis, and for clinicians to direct patients to appropriate diagnostic pathways.

Deep phenotyping classical galactosemia: clinical outcomes and biochemical markers.

Early diagnosis and dietary treatment do not prevent long-term complications, which mostly affect the central nervous system in classical galactosemia patients. The clinical outcome of patients is highly variable, and there is an urgent need for prognostic biomarkers. The aim of this study was first to increase knowledge on the natural history of classical galactosemia by studying a cohort of patients with varying geno- and phenotypes and second to study the association between clinical outcomes and two possible prognostic biomarkers. In addition, the association between abnormalities on brain MRI and clinical outcomes was investigated. Classical galactosemia patients visiting the galactosemia expertise outpatient clinic of the Amsterdam University Medical Centre were evaluated according to the International Classical Galactosemia guideline with the addition of an examination by a neurologist, serum immunoglobulin G N-glycan profiling and a brain MRI. The biomarkers of interest were galactose-1-phosphate levels and N-glycan profiles, and the clinical outcomes studied were intellectual outcome and the presence or absence of movement disorders and/or primary ovarian insufficiency. Data of 56 classical galactosemia patients are reported. The intellectual outcome ranged from 45 to 103 (mean 77 ± 14) and was <85 in 62%. Movement disorders were found in 17 (47%) of the 36 tested patients. In females aged 12 years and older, primary ovarian insufficiency was diagnosed in 12 (71%) of the 17 patients. Significant differences in N-glycan peaks were found between controls and patients. However, no significant differences in either N-glycans or galactose-1-phosphate levels were found between patients with a poor (intellectual outcome < 85) and normal intellectual outcome (intellectual outcome ≥ 85), and with or without movement disorders or primary ovarian insufficiency. The variant patients detected by newborn screening, with previously unknown geno- and phenotypes and currently no long-term complications, demonstrated significantly lower galactose-1-phospate levels than classical patients (P < 0.0005). Qualitative analysis of the MRI's demonstrated brain abnormalities in 18 of the 21 patients, more severely in patients with a lower intellectual outcome and/or with movement disorders. This study demonstrates a large variability in clinical outcome, which varies from a below average intelligence, movement disorders and in females primary ovarian insufficiency to a normal clinical outcome. In our cohort of classical galactosemia patients, galactose-1-phosphate levels and N-glycan variations were not associated with clinical outcomes, but galactose-1-phosphate levels did differentiate between classical and variant patients detected by newborn screening. The correlation between brain abnormalities and clinical outcome should be further investigated by quantitative analysis of the MR images. The variability in clinical outcome necessitates individual and standardized evaluation of all classical galactosemia patients.

Multidisciplinary approach in medicine: successful pregnancy in a patient with hyperinsulinism/hyperammonaemia (HI/HA) syndrome.

This case illustrates the importance of multidisciplinary counselling and management of pregnancies in women with complex medical conditions, especially concerning women with cognitive impairment. We present a woman with hyperinsulinism/hyperammonaemia (HI/HA) syndrome. This syndrome is characterised by recurrent episodes of hypoglycaemia and elevated ammonia levels, which are potentially harmful to both the patient and a developing fetus. We describe a successful multidisciplinary approach during the pregnancy of a mentally challenged patient with HI/HA syndrome. This case illustrates the importance of personalised counselling during the preconception period and emphasises to include all disciplines involved in the medical and daily care of such a patient. In our case, the extensive multidisciplinary care during the preconception period, pregnancy, delivery and postpartum period resulted in a good maternal and neonatal outcome.

Toward newborn screening of cerebrotendinous xanthomatosis: results of a biomarker research study using 32,000 newborn dried blood spots.

PURPOSE: Cerebrotendinous xanthomatosis (CTX) is a treatable hereditary disorder caused by the deficiency of sterol 27-hydroxylase, which is encoded by the CYP27A1 gene. Different newborn screening biomarkers for CTX have been described, including 7α,12α-dihydroxy-4-cholesten-3-one (7α12αC4), 5ß-cholestane-3α,7α,12α,25-tetrol glucuronide (GlcA-tetrol), the ratio of GlcA-tetrol to tauro-chenodeoxycholic acid (t-CDCA) (GlcA-tetrol/t-CDCA), and the ratio of tauro-trihydroxycholestanoic acid (t-THCA) to GlcA-tetrol (t-THCA/GlcA-tetrol). We set out to evaluate these screening methods in a research study using over 32,000 newborn dried blood spots (DBS). METHODS: Metabolites were extracted from DBS with methanol containing internal standard, which was then quantified by ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). RESULTS: The measurement of 7α12αC4 was complicated by isobaric interferences and was discontinued. A total of 32,737 newborns were screened based on the GlcA-tetrol concentration in DBS. GlcA-tetrol/t-CDCA and t-THCA/GlcA-tetrol ratios were also calculated. Newborns displaying both elevated GlcA-tetrol and GlcA-tetrol/t-CDCA ratio were considered to be screen positives. The t-THCA/GlcA-tetrol ratio was used to further distinguish CTX screen positives from Zellweger Spectrum Disorder (ZSD) screen positives. Only one newborn displayed both elevated GlcA-tetrol concentration in DBS and a typical CTX biochemical profile. This newborn was interpreted as a CTX-affected patient as CYP27A1 gene sequencing identified two known pathogenic variants. CONCLUSION: The results indicate that both GlcA-tetrol and the GlcA-tetrol/t-CDCA ratio are excellent CTX biomarkers suitable for newborn screening. By characterizing the relationship of GlcA-tetrol, t-CDCA, and t-THCA as secondary markers, 100% assay specificity can be achieved.