Triheptanoin in patients with long-chain fatty acid oxidation disorders: clinical experience in Italy.

BACKGROUND: Long-chain fatty acid oxidation disorders (LC-FAOD) are rare and potentially life-threatening diseases that cause deficient energy production and accumulation of toxic metabolites. Despite dietary management, adherence to maximum fasting guidelines, restricted long-chain triglyceride intake and supplementation with medium-chain triglyceride (MCT) oil (current standard of care), most patients experience recurrent decompensation episodes that can require hospitalisation. Herein, we analysed the effectiveness and safety of triheptanoin (a highly purified, synthetic medium odd-chain triglyceride) treatment in a cohort of Italian patients with LC-FAOD. METHODS: This retrospective, nationwide study included nine patients with LC-FAOD who switched from standard therapy with MCT oil to triheptanoin oral liquid. Data were collected between 2018 and 2022. Clinical outcome measures were the number and duration of intercurrent catabolic episodes and number and duration of metabolic decompensation episodes requiring hospitalisation. Creatine kinase (CK) levels and treatment-related adverse effects were also reported. RESULTS: Patients were provided a mean ± standard deviation (SD) triheptanoin dose of 1.5 ± 0.9 g/kg/day in four divided administrations, which accounted for 23.9 ± 8.9% of patients' total daily caloric intake. Triheptanoin treatment was started between 2.7 and 16 years of age and was continued for 2.2 ± 0.9 years. The number of intercurrent catabolic episodes during triheptanoin treatment was significantly lower than during MCT therapy (4.3 ± 5.3 vs 22.0 ± 22.2; p = 0.034), as were the number of metabolic decompensations requiring hospitalisation (mean ± SD: 2.0 ± 2.5 vs 18.3 ± 17.7; p = 0.014), and annualised hospitalisation rates and duration. Mean CK levels (outside metabolic decompensation episodes) were lower with triheptanoin treatment versus MCT oil for seven patients. No intensive care unit admissions were required during triheptanoin treatment. Epigastric pain and diarrhoea were recorded as adverse effects during both MCT and triheptanoin treatment. CONCLUSIONS: The significant improvement in clinical outcome measures after the administration of triheptanoin highlights that this treatment approach can be more effective than MCT supplementation in patients with LC-FAOD. Triheptanoin was well tolerated and decreased the number of intercurrent catabolic episodes, metabolic decompensation episodes requiring hospitalisation, and the annualised rate and duration of hospitalisations.

Endocrinological features and epileptic encephalopathy in COX deficiency due to SCO1 mutations: case series and review of literature.

Context: Cytochrome C oxidase (COX) is the fourth component of the respiratory chain and is located within the internal membrane of mitochondria. COX deficiency causes an inherited mitochondrial disease with significant genetic and phenotypic heterogeneity. Four clinical subtypes have been identified, each with distinct phenotypes and genetic variants. Mitochondrial complex IV deficiency nuclear type 4 (MC4DN4) is a form of COX deficiency associated with pathogenic variants in the SCO1 gene. Case description: We describe three patients with MC4DN4 with developmental and epileptic encephalopathy (DEE), hypopituitarism, and SCO1 pathogenic variants. These patients' phenotypes considerably differ from previously reported MC4DN4 phenotypes as they associate DEE with progressive hypopituitarism and survival beyond the first months after birth. Pituitary deficiency in these patients progressively worsened and mainly involved growth hormone secretion and thyroid function. Conclusions: Our findings expand knowledge of phenotypic variability in MC4DN4 and suggest that SCO1 is a candidate gene for genetic hypopituitarism and DEE. Significance statement: Our paper describes three patients affected by MC4DN4 with hypopituitarism and developmental and epileptic encephalopathy (DEE), two features that have never been associated with this condition. In addition, we reviewed the clinical features of all previous cases of MC4DN4 to give the other clinicians a wide picture of the clinical phenotype of this genetic disease. We hope that the publication of our data may help others to identify this disease and consider the chance to analyze the SCO1 gene in cases of DEE associated with pituitary dysfunction. Our article contributes to expanding the spectrum of genetic hypopituitarism and proposes a model to explain an association between this condition, mitochondrial anomalies, and neurodevelopmental defects.

Avalglucosidase alfa in infantile-onset Pompe disease: A snapshot of real-world experience in Italy.

Introduction: Infantile-onset Pompe disease (IOPD) is due to mutations in the GAA gene leading to profound deficiency of the lysosomal enzyme α-1,4-glucosidase. The disease is characterized by severe hypotonia, hypertrophic cardiomyopathy, macroglossia, and liver enlargement with onset in the first months of life. In the late-onset form (LOPD), muscle signs predominate with a clinical picture resembling muscle dystrophies. Enzyme replacement therapy with alglucosidase alfa (rhGAA) has been available since 2006 and patients treated with the enzyme show improved outcomes. Nevertheless, there is evidence that some patients have a suboptimal response or, after an initial improvement, reach a plateau with stabilization of the clinical picture. Thus, a new enzyme formulation, avalglucosidase alfa (neoGAA), with a higher degree of mannosylation, was developed. Methods: We conducted a multicenter survey that collected data on four patients with IOPD, aged 6 to 16 years, who were switched to neoGAA thanks to a compassionate use program, after being treated for an average of 11.5 years with rhGAA. Follow-up data, including biochemical parameters and clinical features, were analyzed to determine clinical outcomes and the safety profile after a mean of 9 months. Results: Patients with IOPD who were treated with neoGAA showed a positive change in biomarker levels. Moreover, the clinical picture revealed improved motor performance and cardiac parameters in patients who previously responded poorly. Conclusion: This study highlights the improved efficacy of neoGAA, as a next generation enzyme replacement therapy, in 4 Italian patients with IOPD. Several clinical parameters showed a positive response to the new formulation suggesting that, if used at diagnosis, neoGAA may result in better outcomes for patients with IOPD.

Generation of a human induced pluripotent stem cell line from a patient with GM3 synthase deficiency using self-replicating RNA vector.

GM3 synthase deficiency (GM3SD) is caused by biallelic variants in the ST3GAL5 gene. Early clinical features of GM3SD include infantile onset of severe irritability and feeding difficulties, early intractable seizures, growth failure, hypotonia, sensorineural hearing impairment. We describe the generation and characterization the human induced pluripotent stem cell (hiPSC) line derived from fibroblasts of a 13-year-old girl with GM3 synthase deficiency resulted compound heterozygous for two new variants in the ST3GAL5 gene, c.1166A > G (p.His389Arg) and the c.1024G > A (p.Gly342Ser). The generated hiPSC line shows a normal karyotype, expresses pluripotency markers, and is able to differentiate into the three germ layers.

Deoxyguanosine kinase deficiency: natural history and liver transplant outcome.

Autosomal recessive pathogenetic variants in the DGUOK gene cause deficiency of deoxyguanosine kinase activity and mitochondrial deoxynucleotides pool imbalance, consequently, leading to quantitative and/or qualitative impairment of mitochondrial DNA synthesis. Typically, patients present early-onset liver failure with or without neurological involvement and a clinical course rapidly progressing to death. This is an international multicentre study aiming to provide a retrospective natural history of deoxyguanosine kinase deficient patients. A systematic literature review from January 2001 to June 2023 was conducted. Physicians of research centres or clinicians all around the world caring for previously reported patients were contacted to provide followup information or additional clinical, biochemical, histological/histochemical, and molecular genetics data for unreported cases with a confirmed molecular diagnosis of deoxyguanosine kinase deficiency. A cohort of 202 genetically confirmed patients, 36 unreported, and 166 from a systematic literature review, were analyzed. Patients had a neonatal onset (≤ 1 month) in 55.7% of cases, infantile (>1 month and ≤ 1 year) in 32.3%, pediatric (>1 year and ≤18 years) in 2.5% and adult (>18 years) in 9.5%. Kaplan-Meier analysis showed statistically different survival rates (P < 0.0001) among the four age groups with the highest mortality for neonatal onset. Based on the clinical phenotype, we defined four different clinical subtypes: hepatocerebral (58.8%), isolated hepatopathy (21.9%), hepatomyoencephalopathy (9.6%), and isolated myopathy (9.6%). Muscle involvement was predominant in adult-onset cases whereas liver dysfunction causes morbidity and mortality in early-onset patients with a median survival of less than 1 year. No genotype-phenotype correlation was identified. Liver transplant significantly modified the survival rate in 26 treated patients when compared with untreated. Only six patients had additional mild neurological signs after liver transplant. In conclusion, deoxyguanosine kinase deficiency is a disease spectrum with a prevalent liver and brain tissue specificity in neonatal and infantile-onset patients and muscle tissue specificity in adult-onset cases. Our study provides clinical, molecular genetics and biochemical data for early diagnosis, clinical trial planning and immediate intervention with liver transplant and/or nucleoside supplementation.

Early neurological signs in infants identified through neonatal screening for SMA: do they predict outcome?

Neonatal screening for SMA has allowed the identification of infants who may present with early clinical signs. Our aim was to establish whether the presence and the severity of early clinical signs have an effect on the development of motor milestones. Infants identified through newborn screening were prospectively assessed using a structured neonatal neurological examination and an additional module developed for the assessment of floppy infants. As part of the follow-up, all infants were assessed using the HINE-2 to establish developmental milestones. Only infants with at least 24 months of follow-up were included. Normal early neurological examination (n = 11) was associated with independent walking before the age of 18 months while infants with early clinical signs of SMA (n = 4) did not achieve ambulation (duration follow-up 33.2 months). Paucisymptomatic patients (n = 3) achieved ambulation, one before the age of 18 months and the other 2 between 22 and 24 months.  Conclusion: Our findings suggest that early clinical signs may contribute to predict motor milestones development. What is Known: • There is increasing evidence of heterogeneity among the SMA newborns identified via NBS. • The proposed nosology describes a clinically silent disease, an intermediate category ('paucisymptomatic') and 'symptomatic SMA'. What is New: • The presence of minimal clinical signs at birth does not prevent the possibility to achieve independent walking but this may occur with some delay. • The combination of genotype at SMN locus and clinical evaluation may better predict the possibility to achieve milestones.

DNAJC12 deficiency: Mild hyperphenylalaninemia and neurological impairment in two siblings.

Background: DNAJC12 co-chaperone protein deficiency has been recently described as a stand-alone metabolic disorder explaining many cases of mild hyperphenylalaninemia (HPA) that are not caused by variants in the PAH gene, which encodes for the hepatic enzyme phenylalanine hydroxylase (PAH), or inGCH1, PTS, QDPR, PCBD1 and DHPR, involved in tetrahydrobiopterin (BH4) biosynthesis and activity. Results: We describe two sisters born to consanguineous parents. The youngest sister (Patient 1), initially asymptomatic, tested positive at NewBorn Screening (NBS) for mild HPA. After variants in the PAH and BH4 related-genes were excluded, we performed DNAJC12 genetic analysis and found a previously described homozygous deletion [NM_021800.3: c.58_59del p.(Gly20Metfs*2)]. The older sister (Patient 2), homozygous for the same variant and exhibiting mild HPA, was diagnosed subsequently and presented with ataxia and repeated falls, upper limb dyskinesia, intentional tremor, and mild intellectual disability. Patient 1 was started on treatment with low Phenylalanine (Phe) diet, BH4, l-3,4-dihydroxyphenylalanine/carbidopa (L-DOPA) and 5-OH-Tryptophan, soon after diagnosis, and despite poor adherence to the dietary regimen, only manifested language impairment at last follow-up (age 5 years and 4 months). Patient 2, who started the same treatment at school age, experienced a minimal progression of neurological symptoms, with some improvement in her motor skills. Conclusions: These two new patients with DNAJC12-associated HPA, in addition to previous reports, point to DNAJC12 deficiency as a new metabolic syndrome that must be considered in patients with unexplained HPA.

Cardiac Involvement in Classical Organic Acidurias: Clinical Profile and Outcome in a Pediatric Cohort.

BACKGROUND: Cardiac involvement is reported in a significant proportion of patients with classical organic acidurias (OAs), contributing to disability and premature death. Different cardiac phenotypes have been described, among which dilated cardiomyopathy (DCM) is predominant. Despite recent progress in diagnosis and treatment, the natural history of patients with OAs remains unresolved, specifically with regard to the impact of cardiac complications. We therefore performed a retrospective study to address this issue at our Referral Center for Pediatric Inherited Errors of Metabolism. METHODS: Sixty patients with OAs (propionic (PA), methylmalonic (MMA) and isovaleric acidemias and maple syrup urine disease) diagnosed from 2000 to 2022 were systematically assessed at baseline and at follow-up. RESULTS: Cardiac anomalies were found in 23/60 OA patients, all with PA or MMA, represented by DCM (17/23 patients) and/or acquired long QT syndrome (3/23 patients). The presence of DCM was associated with the worst prognosis. The rate of occurrence of major adverse cardiac events (MACEs) at 5 years was 55% in PA with cardiomyopathy; 35% in MMA with cardiomyopathy; and 23% in MMA without cardiomyopathy. Liver transplantation was performed in seven patients (12%), all with PA or MMA, due to worsening cardiac impairment, and led to the stabilization of metabolic status and cardiac function. CONCLUSIONS: Cardiac involvement was documented in about one third of children diagnosed with classical OAs, confined to PA and MMA, and was often associated with poor outcome in over 50%. Etiological diagnosis of OAs is essential in guiding management and risk stratification.

Communicating a Positive Result at Newborn Screening and Parental Distress.

The assumption of this study is strictly connected to the need to focus and to know more about the impact on the psychological state of the parents whose newborn babies get a positive result at Expanded Newborn Screening (ENS). As clinical experience shows us, this aspect seems to have a potentially lasting resonance on the way the disease will be managed and handled in the family, leading to potential negative effects and repercussions on the child's wellbeing and on the quality of life within the family. On the basis of this and on the evidence emerging from a review of the literature, this study aims to investigate and objectify possible distress indicators elicited at the moment of the communication of a positive result at ENS. Questionnaires containing the Beck Depression Inventory-II, the State-Trait Anxiety Inventory-Y, and the Short Form 36 Health Survey tests were administered to the parents of 87 newborns who received positive results at ENS. The parents of 32 babies expressed the presence of discomfort potentially related to the communication of a positive result at ENS.

Management of methylmalonic acidemia (MMA) with N-carbamylglutamate: A case report from Italy.

BACKGROUND: Methylmalonic acidemia (MMA) is an inborn error of metabolism whose optimal management, especially in the long-term remains to be established. METHODS: We describe the case of a child with MMA mut0 who was in a cycle of episodes of decompensation and hospitalization when we started to use carglumic acid (CA), a well-known adjunctive therapy to standard care for the treatment of acute hyperammonemia due to MMA. RESULTS: Using the lowest effective therapeutic dose of CA and adjusting the patient's diet with caloric and protein intake adequate for her age and pathology, we managed to keep ammonium levels within the normal range, and to ensure a normal growth pattern. CONCLUSION: The present case adds further confirmation of the long-term management of MMA using CA, focusing on the long duration of follow up and on the use of a lower dose of CA in real life settings.

Generation of human induced pluripotent stem cell line (AOUMEYi001-A) from a patient affected by Congenital disorders of glycosylation (ALG8-CDG) using self-replicating RNA vector.

Congenital Disorders of Glycosylation (CDG) are rare inherited metabolic diseases caused by genetic defects in the glycosylation of proteins and lipids. In this study, we describe the generation and characterization of one human induced pluripotent stem cell (hiPSC) line from a 15-year-old male patient with CDG. The patient carried three variants, one (c.122G > A; p.Arg41Gln) inherited from his father and two (c.445 T > G; p.Leu149Arg and the novel c.980C > G; p.Thr327Arg) inherited from his mother in the ALG8 gene (OMIM #608103). The generated hiPSC line shows a normal karyotype, expresses pluripotency markers, and is able to differentiate into the three germ layers.

Clinical implementation of RNA sequencing for Mendelian disease diagnostics.

BACKGROUND: Lack of functional evidence hampers variant interpretation, leaving a large proportion of individuals with a suspected Mendelian disorder without genetic diagnosis after whole genome or whole exome sequencing (WES). Research studies advocate to further sequence transcriptomes to directly and systematically probe gene expression defects. However, collection of additional biopsies and establishment of lab workflows, analytical pipelines, and defined concepts in clinical interpretation of aberrant gene expression are still needed for adopting RNA sequencing (RNA-seq) in routine diagnostics. METHODS: We implemented an automated RNA-seq protocol and a computational workflow with which we analyzed skin fibroblasts of 303 individuals with a suspected mitochondrial disease that previously underwent WES. We also assessed through simulations how aberrant expression and mono-allelic expression tests depend on RNA-seq coverage. RESULTS: We detected on average 12,500 genes per sample including around 60% of all disease genes-a coverage substantially higher than with whole blood, supporting the use of skin biopsies. We prioritized genes demonstrating aberrant expression, aberrant splicing, or mono-allelic expression. The pipeline required less than 1 week from sample preparation to result reporting and provided a median of eight disease-associated genes per patient for inspection. A genetic diagnosis was established for 16% of the 205 WES-inconclusive cases. Detection of aberrant expression was a major contributor to diagnosis including instances of 50% reduction, which, together with mono-allelic expression, allowed for the diagnosis of dominant disorders caused by haploinsufficiency. Moreover, calling aberrant splicing and variants from RNA-seq data enabled detecting and validating splice-disrupting variants, of which the majority fell outside WES-covered regions. CONCLUSION: Together, these results show that streamlined experimental and computational processes can accelerate the implementation of RNA-seq in routine diagnostics.

Monoallelic KIF1A-related disorders: a multicenter cross sectional study and systematic literature review.

BACKGROUND: Monoallelic variants in the KIF1A gene are associated with a large set of clinical phenotypes including neurodevelopmental and neurodegenerative disorders, underpinned by a broad spectrum of central and peripheral nervous system involvement. METHODS: In a multicenter study conducted in patients presenting spastic gait or complex neurodevelopmental disorders, we analyzed the clinical, genetic and neuroradiological features of 28 index cases harboring heterozygous variants in KIF1A. We conducted a literature systematic review with the aim to comparing our findings with previously reported KIF1A-related phenotypes. RESULTS: Among 28 patients, we identified nine novel monoallelic variants, and one a copy number variation encompassing KIF1A. Mutations arose de novo in most patients and were prevalently located in the motor domain. Most patients presented features of a continuum ataxia-spasticity spectrum with only five cases showing a prevalently pure spastic phenotype and six presenting congenital ataxias. Seventeen mutations occurred in the motor domain of the Kinesin-1A protein, but location of mutation did not correlate with neurological and imaging presentations. When tested in 15 patients, muscle biopsy showed oxidative metabolism alterations (6 cases), impaired respiratory chain complexes II + III activity (3/6) and low CoQ10 levels (6/9). Ubiquinol supplementation (1gr/die) was used in 6 patients with subjective benefit. CONCLUSIONS: This study broadened our clinical, genetic, and neuroimaging knowledge of KIF1A-related disorders. Although highly heterogeneous, it seems that manifestations of ataxia-spasticity spectrum disorders seem to occur in most patients. Some patients also present secondary impairment of oxidative metabolism; in this subset, ubiquinol supplementation therapy might be appropriate.

Clinical, imaging, biochemical and molecular features in Leigh syndrome: a study from the Italian network of mitochondrial diseases.

BACKGROUND: Leigh syndrome (LS) is a progressive neurodegenerative disorder associated with primary or secondary dysfunction of mitochondrial oxidative phosphorylation and is the most common mitochondrial disease in childhood. Numerous reports on the biochemical and molecular profiles of LS have been published, but there are limited studies on genetically confirmed large series. We reviewed the clinical, imaging, biochemical and molecular data of 122 patients with a diagnosis of LS collected in the Italian Collaborative Network of Mitochondrial Diseases database. RESULTS: Clinical picture was characterized by early onset of several neurological signs dominated by central nervous system involvement associated with both supra- and sub-tentorial grey matter at MRI in the majority of cases. Extraneurological organ involvement is less frequent in LS than expected for a mitochondrial disorder. Complex I and IV deficiencies were the most common biochemical diagnoses, mostly associated with mutations in SURF1 or mitochondrial-DNA genes encoding complex I subunits. Our data showed SURF1 as the genotype with the most unfavorable prognosis, differently from other cohorts reported to date. CONCLUSION: We report on a large genetically defined LS cohort, adding new data on phenotype-genotype correlation, prognostic factors and possible suggestions to diagnostic workup.

The Diagnostic Approach to Mitochondrial Disorders in Children in the Era of Next-Generation Sequencing: A 4-Year Cohort Study.

Mitochondrial diseases (MDs) are a large group of genetically determined multisystem disorders, characterized by extreme phenotypic heterogeneity, attributable in part to the dual genomic control (nuclear and mitochondrial DNA) of the mitochondrial proteome. Advances in next-generation sequencing technologies over the past two decades have presented clinicians with a challenge: to select the candidate disease-causing variants among the huge number of data provided. Unfortunately, the clinical tools available to support genetic interpretations still lack specificity and sensitivity. For this reason, the diagnosis of MDs continues to be difficult, with the new "genotype first" approach still failing to diagnose a large group of patients. With the aim of investigating possible relationships between clinical and/or biochemical phenotypes and definitive molecular diagnoses, we performed a retrospective multicenter study of 111 pediatric patients with clinical suspicion of MD. In this cohort, the strongest predictor of a molecular (in particular an mtDNA-related) diagnosis of MD was neuroimaging evidence of basal ganglia (BG) involvement. Regression analysis confirmed that normal BG imaging predicted negative genetic studies for MD. Psychomotor regression was confirmed as an independent predictor of a definitive diagnosis of MD. The findings of this study corroborate previous data supporting a role for neuroimaging in the diagnostic approach to MDs and reinforce the idea that mtDNA sequencing should be considered for first-line testing, at least in specific groups of children.