Father-to-daughter transmission in late-onset OTC deficiency: an underestimated mechanism of inheritance of an X-linked disease.

BACKGROUND: Ornithine Transcarbamylase Deficiency (OTCD) is an X-linked urea cycle disorder characterized by acute hyperammonemic episodes. Hemizygous males are usually affected by a severe/fatal neonatal-onset form or, less frequently, by a late-onset form with milder disease course, depending on the residual enzymatic activity. Hyperammonemia can occur any time during life and patients could remain non- or mis-diagnosed due to unspecific symptoms. In heterozygous females, clinical presentation varies based on the extent of X chromosome inactivation. Maternal transmission in X-linked disease is the rule, but in late-onset OTCD, due to the milder phenotype of affected males, paternal transmission to the females is possible. So far, father-to-daughter transmission of OTCD has been reported only in 4 Japanese families. RESULTS: We identified in 2 Caucasian families, paternal transmission of late-onset OTCD with severe/fatal outcome in affected males and 1 heterozygous female. Furthermore, we have reassessed the pedigrees of other published reports in 7 additional families with evidence of father-to-daughter inheritance of OTCD, identifying and listing the family members for which this transmission occurred. CONCLUSIONS: Our study highlights how the diagnosis and pedigree analysis of late-onset OTCD may represent a real challenge for clinicians. Therefore, the occurrence of paternal transmission in OTCD should not be underestimated, due to the relevant implications for disease inheritance and risk of recurrence.

Impact of genetic and non-genetic factors on phenotypic diversity in NBAS-associated disease.

Biallelic pathogenic variants in neuroblastoma-amplified sequence (NBAS) cause a pleiotropic multisystem disorder. Three clinical subgroups have been defined correlating with the localisation of pathogenic variants in the NBAS gene: variants affecting the C-terminal region of NBAS result in SOPH syndrome (short stature, optic atrophy, Pelger-Huët anomaly), variants affecting the Sec 39 domain are associated with infantile liver failure syndrome type 2 (ILFS2) and variants affecting the ß-propeller domain give rise to a combined phenotype. However, there is still unexplained phenotypic diversity across the three subgroups, challenging the current concept of genotype-phenotype correlations in NBAS-associated disease. Therefore, besides examining the genetic influence, we aim to elucidate the potential impact of pre-symptomatic diagnosis, emergency management and other modifying variables on the clinical phenotype. We investigated genotype-phenotype correlations in individuals sharing the same genotypes (n = 30 individuals), and in those sharing the same missense variants with a loss-of-function variant in trans (n = 38 individuals). Effects of a pre-symptomatic diagnosis and emergency management on the severity of acute liver failure (ALF) episodes also were analysed, comparing liver function tests (ALAT, ASAT, INR) and mortality. A strong genotype-phenotype correlation was demonstrated in individuals sharing the same genotype; this was especially true for the ILFS2 subgroup. Genotype-phenotype correlation in patients sharing only one missense variant was still high, though at a lower level. Pre-symptomatic diagnosis in combination with an emergency management protocol leads to a trend of reduced severity of ALF. High genetic impact on clinical phenotype in NBAS-associated disease facilitates monitoring and management of affected patients sharing the same genotype. Pre-symptomatic diagnosis and an emergency management protocol do not prevent ALF but may reduce its clinical severity.

The impact of liver transplantation on health-related quality of life in (acute) intoxication-type inborn errors of metabolism.

Organic acidurias (OAs), urea-cycle disorders (UCDs), and maple syrup urine disease (MSUD) belong to the category of intoxication-type inborn errors of metabolism (IT-IEM). Liver transplantation (LTx) is increasingly utilized in IT-IEM. However, its impact has been mainly focused on clinical outcome measures and rarely on health-related quality of life (HRQoL). Aim of the study was to investigate the impact of LTx on HrQoL in IT-IEMs. This single center prospective study involved 32 patients (15 OA, 11 UCD, 6 MSUD; median age at LTx 3.0 years, range 0.8-26.0). HRQoL was assessed pre/post transplantation by PedsQL-General Module 4.0 and by MetabQoL 1.0, a specifically designed tool for IT-IEM. PedsQL highlighted significant post-LTx improvements in total and physical functioning in both patients' and parents' scores. According to age at transplantation (≤3 vs. >3 years), younger patients showed higher post-LTx scores on Physical (p = 0.03), Social (p < 0.001), and Total (p =0.007) functioning. MetabQoL confirmed significant post-LTx changes in Total and Physical functioning in both patients and parents scores (p ≤ 0.009). Differently from PedsQL, MetabQoL Mental (patients p = 0.013, parents p = 0.03) and Social scores (patients p = 0.02, parents p = 0.012) were significantly higher post-LTx. Significant improvements (p = 0.001-0.04) were also detected both in self- and proxy-reports for almost all MetabQoL subscales. This study shows the importance of assessing the impact of transplantation on HrQoL, a meaningful outcome reflecting patients' wellbeing. LTx is associated with significant improvements of HrQol in both self- and parent-reports. The comparison between PedsQL-GM and MetabQoL highlighted that MetabQoL demonstrated higher sensitivity in the assessment of disease-specific domains than the generic PedsQL tool.

Neurologic outcome following liver transplantation for methylmalonic aciduria.

Liver and liver/kidney transplantation are increasingly used in methylmalonic aciduria, but little is known on their impact on CNS. The effect of transplantation on neurological outcome was prospectively assessed in six patients pre- and post-transplant by clinical evaluation and by measuring disease biomarkers in plasma and CSF, in combination with psychometric tests and brain MRI studies. Primary (methylmalonic- and methylcitric acid) and secondary biomarkers (glycine and glutamine) significantly improved in plasma, while they remained unchanged in CSF. Differently, biomarkers of mitochondrial dysfunction (lactate, alanine, and related ratios) significantly decreased in CSF. Neurocognitive evaluation documented significant higher post-transplant developmental/cognitive scores and maturation of executive functions corresponding to improvement of brain atrophy, cortical thickness, and white matter maturation indexes at MRI. Three patients presented post-transplantation reversible neurological events, which were differentiated, by means of biochemical and neuroradiological evaluations, into calcineurin inhibitor-induced neurotoxicity and metabolic stroke-like episode. Our study shows that transplantation has a beneficial impact on neurological outcome in methylmalonic aciduria. Early transplantation is recommended due to the high risk of long-term complications, high disease burden, and low quality of life.

Natural history of epilepsy in argininosuccinic aciduria provides new insights into pathophysiology: A retrospective international study.

OBJECTIVE: Argininosuccinate lyase (ASL) is integral to the urea cycle, which enables nitrogen wasting and biosynthesis of arginine, a precursor of nitric oxide. Inherited ASL deficiency causes argininosuccinic aciduria, the second most common urea cycle defect and an inherited model of systemic nitric oxide deficiency. Patients present with developmental delay, epilepsy, and movement disorder. Here we aim to characterize epilepsy, a common and neurodebilitating comorbidity in argininosuccinic aciduria. METHODS: We conducted a retrospective study in seven tertiary metabolic centers in the UK, Italy, and Canada from 2020 to 2022, to assess the phenotype of epilepsy in argininosuccinic aciduria and correlate it with clinical, biochemical, radiological, and electroencephalographic data. RESULTS: Thirty-seven patients, 1-31 years of age, were included. Twenty-two patients (60%) presented with epilepsy. The median age at epilepsy onset was 24 months. Generalized tonic-clonic and focal seizures were most common in early-onset patients, whereas atypical absences were predominant in late-onset patients. Seventeen patients (77%) required antiseizure medications and six (27%) had pharmacoresistant epilepsy. Patients with epilepsy presented with a severe neurodebilitating disease with higher rates of speech delay (p = .04) and autism spectrum disorders (p = .01) and more frequent arginine supplementation (p = .01) compared to patients without epilepsy. Neonatal seizures were not associated with a higher risk of developing epilepsy. Biomarkers of ureagenesis did not differ between epileptic and non-epileptic patients. Epilepsy onset in early infancy (p = .05) and electroencephalographic background asymmetry (p = .0007) were significant predictors of partially controlled or refractory epilepsy. SIGNIFICANCE: Epilepsy in argininosuccinic aciduria is frequent, polymorphic, and associated with more frequent neurodevelopmental comorbidities. We identified prognostic factors for pharmacoresistance in epilepsy. This study does not support defective ureagenesis as prominent in the pathophysiology of epilepsy but suggests a role of central dopamine deficiency. A role of arginine in epileptogenesis was not supported and warrants further studies to assess the potential arginine neurotoxicity in argininosuccinic aciduria.

The diagnostic challenge of mild citrulline elevation at newborn screening.

Citrulline is a target analyte measured at expanded newborn screening (NBS) and its elevation represents a biomarker for distal urea cycle disorders and citrin deficiency. Altered ratios of citrulline with other urea cycle-related amino acids are helpful for the differential diagnosis. However, the use of cut-off values in screening programmes has raised the issue about the interpretation of mild elevation of citrulline levels detected at NBS, below the usual range observed in the "classical/severe" forms of distal urea cycle disorders and in citrin deficiency. Herein, we report ten subjects with positive NBS for a mild elevation of citrulline (<100 µmol/L), in whom molecular investigations revealed carriers status for argininosuccinate synthase deficiency, a milder form of argininosuccinate lyase deficiency and two other diseases, lysinuric protein intolerance and dihydrolipoamide dehydrogenase deficiency, not primarily affecting the urea cycle. To guide the diagnostic process, we have designed an algorithm for mild citrulline elevation (<100 µmol/L) at NBS, which expands the list of disorders to be included in the differential diagnosis.

Correlation between the Mandibular Lingula Position and Some Anatomical Landmarks in Cone Beam CT.

BACKGROUND: the position of the mandibular lingula (Li) affects the success rate of the inferior alveolar nerve block (IANB) and ramus osteotomies. This study evaluated the position of the Li, to investigate the anatomical relationship between the Li and some anatomical measurements using cone beam computed tomography (CBCT). METHODS: 201 hemimandibular CBCTs of 111 patients (43 males and 68 females; 18 to 88 years old) were retrospectively evaluated. The Li location was determined from the lingula tip to: the occlusal plane, the anterior and posterior borders of the mandibular ramus, the lower border of the mandible, the distal surface of the mandibular second molar, and the mandibular notch. We evaluated the correlations between the Li and the anteroposterior diameter of the mandibular ramus; the vertical distance between condyle and mandibular angle; the mesial-distal diameter of the first, second, and third mandibular molar, the intercanine distance, the intermolar distances among the first, second, and third mandibular molars; the distance between the intermolar line of the first molar and midline, and the length of the mandibular body. RESULTS: the vertical distance of the Li from the occlusal plane was 11.22 ± 4.27 mm. Some parameters significantly correlated with the anatomical measurements taken into consideration. CONCLUSIONS: the present study provides new information concerning the Li and mandibular anatomy in the Italian population. Moreover, by correlating some anatomic measurements to the Li position, the localization of the Li is made possible, indirectly through the measurement of some distances between anatomical landmarks.

Ethylmalonic encephalopathy and liver transplantation: long-term outcome of the first treated patient.

BACKGROUND: Ethylmalonic encephalopathy (EE) is a severe intoxication-type metabolic disorder with multisystem clinical features and leading to early death. In 2014, based on the promising results obtained by liver-targeted gene therapy in Ethe1-/- mouse model, we successfully attempted liver transplantation in a 9-month-old EE girl. Here we report her long-term follow-up, lasting over 6 years, with a comprehensive evaluation of clinical, instrumental and biochemical assessments. RESULTS: Neurological signs initially reverted, with a clinical stabilization during the entire follow-up course. Accordingly, gross motor functions improved and then stabilized. Psychomotor evaluations documented an increasing communicative intent, the acquisition of new social skills and the capability to carry out simple orders. Neurophysiological assessments, which included EEG, VEP/ERG and BAEPs, remained unchanged. Brain MRI also stabilized, showing no further lesions and cerebral atrophy improvement. Compared to pre-transplant assessments, urinary ethylmalonic acid strikingly reduced, and plasma thiosulphate fully normalized. The child maintained good clinical conditions and never experienced metabolic crises nor epileptic seizures. CONCLUSIONS: The long-term follow-up of the first EE transplanted patient demonstrates that liver transplantation stabilizes, or even improves, disease course, therefore representing a potentially elective option especially in early-diagnosed patients, such as those detected by newborn screening, before irreversible neurological damage occurs.

Novel NDUFA12 variants are associated with isolated complex I defect and variable clinical manifestation.

Isolated biochemical deficiency of mitochondrial complex I is the most frequent signature among mitochondrial diseases and is associated with a wide variety of clinical symptoms. Leigh syndrome represents the most frequent neuroradiological finding in patients with complex I defect and more than 80 monogenic causes have been involved in the disease. In this report, we describe seven patients from four unrelated families harboring novel NDUFA12 variants, with six of them presenting with Leigh syndrome. Molecular genetic characterization was performed using next-generation sequencing combined with the Sanger method. Biochemical and protein studies were achieved by enzymatic activities, blue native gel electrophoresis, and western blot analysis. All patients displayed novel homozygous mutations in the NDUFA12 gene, leading to the virtual absence of the corresponding protein. Surprisingly, despite the fact that in none of the analyzed patients, NDUFA12 protein was detected, they present a different onset and clinical course of the disease. Our report expands the array of genetic alterations in NDUFA12 and underlines phenotype variability associated with NDUFA12 defect.

A new UHPLC-MS/MS method for the screening of urinary oligosaccharides expands the detection of storage disorders.

BACKGROUND: Oligosaccharidoses are storage disorders due to enzymatic defects involved in the breakdown of the oligosaccharidic component of glycosylated proteins. The defect cause the accumulation of oligosaccharides (OS) and, depending on the lacking enzyme, results in characteristic profiles which are helpful for the diagnosis. We developed a new tandem mass spectrometry method for the screening of urinary OS which was applied to identify a large panel of storage disorders. METHODS: The method was set-up in urine and dried urine spots (DUS). Samples were analysed, without derivatization and using maltoheptaose as internal standard, by UHPLC-MS/MS with MRM acquisition of target OS transitions, including Glc4, the biomarker of Pompe disease. The chromatographic run was < 30 min. Samples from patients with known storage disorders were used for clinical validation. RESULTS: The method allowed to confirm the diagnosis of oligosaccharidoses (sialidosis, α-/ß-mannosidosis, fucosidosis, aspartylglucosaminuria) and of GM1 and GM2 (Sandhoff type) gangliosidosis, by detecting specific OS profiles. In other storage disorders (mucolipidosis II and III, mucopolysaccharidosis type IVB) the analyisis revealed abnormal OS excretion with non-specific profiles. Besides Pompe disease, the tetrasaccharide Glc4 was increased also in disorders of autophagy (Vici syndrome, Yunis-Varon syndrome, and Danon disease) presenting cardiomuscular involvement with glycogen storage. Overall, results showed a clear separation between patients and controls, both in urine and in DUS. CONCLUSION: This new UHPLC/MS-MS method, which is suitable for rapid and easy screening of OS in urine and DUS, expands the detection of storage disorders from oligosaccharidoses to other diseases, including the novel category of inherited disorders of autophagy.

Determination of the valence band edge of Fe oxide nanoparticles dispersed in aqueous solution through resonant photoelectron spectroscopy from a liquid microjet.

We use X-ray photoemission and a near ambient pressure with a liquid microjet setup to investigate the electronic structure of FeOOH nanoparticles dispersed in aqueous solution. In particular, we show that by using X-ray resonant photoemission in dilute solutions, we can overcome the limits of conventional photoemission such as low nanoparticle-to-solvent signal ratio, and local nanoparticle charging and measure the valence band structure of FeOOH nanoparticles in aqueous solution with chemical specificity. The resonant photoemission signal across the Fe 2p3/2 absorption edge is measured for 2 wt% aqueous solutions of FeOOH nanoparticles (NPs) and the valence band maximum (VBM) of the hydrated FeOOH nanoparticles is determined. We compare the obtained VBM value in aqueous solution to that of FeOOH NPs in the dry phase. We show that the valence band edge position of NPs in the liquid phase can be accurately predicted from the values obtained in the dry phase provided that a simple potential shift due to solution chemistry is applied. Our results demonstrate the suitability of resonant photoemission in measuring the electronic structure of strongly diluted nanosystems where the conventional non-resonant photoemission technique fails.

Health-related quality of life in paediatric patients with intoxication-type inborn errors of metabolism: Analysis of an international data set.

Acute intoxication-type inborn errors of metabolism (IT-IEM) such as urea cycle disorders and non-acute IT-IEM such as phenylketonuria have a major impact on paediatric patients' life. Patients have to adhere to a strict diet but may face neurocognitive impairment and - in acute diseases - metabolic decompensations nevertheless. Research on the subjective burden of IT-IEM remains sparse. Studies with appropriate sample sizes are needed to make valid statements about health-related quality of life (HrQoL) in children and adolescents with IT-IEM. Six international metabolic centres contributed self-reports and proxy reports of HrQoL (assessed with the Paediatric Quality of Life Inventory) to the final data set (n = 251 patients; age range 2.3-18.8 years). To compare HrQoL of the patient sample with norm data and between acute and non-acute IT-IEM, t tests were conducted. To examine the influence of child age, sex, diagnosis and current dietary treatment on HrQoL, multiple linear regression analyses were conducted. Self-reports and proxy reporst showed significantly lower HrQoL total scores for children with IT-IEM compared to healthy children. Current dietary treatment significantly predicted lower proxy reported total HrQoL. Children with non-acute IT-IEM reported significantly lower psychosocial health and emotional functioning than children with acute IT-IEM. The patient sample showed significantly impaired HrQoL and a diet regimen remains a risk factor for lower HrQoL. Differences in HrQoL between acute and non-acute IT-IEM subgroups indicate that factors beyond symptom severity determine the perception of disease burden. Identifying these factors is of crucial importance to develop and implement appropriate interventions for those in need.

Orofacial features and pediatric dentistry in the long-term management of Infantile Pompe Disease children.

BACKGROUND: Glycogen storage disease type II (GSDII) or Pompe disease is a rare autosomal recessive metabolic disorder that leads to intracellular glycogen storage in many tissues, mainly in skeletal muscle, heart and liver. Facial muscle weakness and altered craniofacial growth are very common in Pompe disease children. In this paper we describe the orofacial features in two children affected by GSDII and illustrate a multidisciplinary approach that involved enzyme replace therapy, non-invasive ventilation (NIV) and pediatric dentistry with 5-year follow-up. RESULTS: Two Infantile Pompe Disease children were examined by a pediatric dentist at the age of 4 and 5 years old respectively. The orofacial examination showed typical facies with similar features: hypotonia of facial and tongue muscles, lip incompetence, narrow palate with reduction in transversal dimension of the upper dental arch, macroglossia, low position of the tip of the tongue, concave profile, Class III malocclusion with hypoplasia of maxillary-malar area and mandibular prognathism. Myofunctional therapy and orthodontic treatment consisted in oral muscle exercises associated to intraoral and extraoral orthodontic devices. NIV facial mask was substituted with a nasal pillow mask in order to avoid external pressure on the mid-face which negatively influences craniofacial growth. CONCLUSIONS: This paper evidences that the pediatric dentist plays an important role in craniofacial growth control, oral function rehabilitation and, therefore, in the improvement of the quality of life of Pompe children and their families. Therefore an early pediatric dental evalutation should be included in the multidisciplinary management of children suffering from Infantile Pompe Disease.

Plasma methylcitric acid and its correlations with other disease biomarkers: The impact in the follow up of patients with propionic and methylmalonic acidemia.

Methylcitric acid (MCA) analysis has been mainly utilized for the diagnosis of propionate disorders or as a second-tier test in newborn screening, but its utility for patients monitoring still needs to be established. We explored the potential contribution of MCA in the long-term management of organic acidurias. We prospectively evaluated plasma MCA and its relationship with disease biomarkers, clinical status, and disease burden in 22 patients, 13 with propionic acidemia (PA) and nine with methylmalonic acidemia (MMA) on standard treatment and/or after transplantation. Samples were collected at scheduled routine controls or during episodes of metabolic decompensation (MD), 10 patients were evaluated after transplantation (six liver, two combined liver and kidney, 2 kidney). MCA levels were higher in PA compared to MMA and its levels were not influenced by the clinical status (MD vs well state). In MMA, MCA was higher in elder patients and, along with fibroblast growth factor 21 (FGF21) and plasma methylmalonic acid, negatively correlated with GFR. In both diseases, MCA correlated with ammonia, glycine, lysine, C3, and the C3/C2, C3/C16 ratios. The disease burden showed a direct correlation with MCA and FGF21, for both diseases. All transplanted patients showed a significant reduction of MCA in comparison to baseline values, with some differences dependent on the type of transplantation. Our study provided new insights in understanding the disease pathophysiology, showing similarities between MCA and FGF21 in predicting disease burden, long-term complications and in evaluating the impact of organ transplantation.

Early visual and neuro-development in preterm infants with and without retinopathy.

BACKGROUND: Retinopathy of prematurity (ROP) is often associated with visual impairment and multiple developmental disabilities. AIMS: As most of the previous studies include infants with brain lesions, that can determine visual impairment per se, a cohort of low neurological risk preterm infants without ROP and with various degree of severity of ROP was assessed in order to establish visual and neurodevelopmental outcome. STUDY DESIGN: Preterm infants born at <31 weeks gestation, without major brain lesions, underwent visual function assessment at 1 year corrected age and neurodevelopmental assessment at 2 years corrected age. SUBJECTS: One hundred and five infants were included in the study: 42 infants did not develop ROP, 7 reached stage 1 in zone 2 ROP, 37 reached prethreshold (untreated) type 2 ROP. The remaining 19 infants were classified as type 1 ROP. OUTCOME MEASURES: Visual function (including fixing, tracking, visual acuity, visual field, attention at distance and nystagmus) were assessed at 12 months corrected age and Griffiths Scales at 2 years corrected age. RESULTS: The severity of ROP was strongly correlated (p < 0.001) with both visual function at 1 year and neurodevelopment at 2 years. Similarly, the presence of nystagmus was also strongly correlated with visual and neurodevelopmental sequelae. CONCLUSIONS: Infants with no or milder retinopathy showed normal visual function at 1 year and neurodevelopment at 2 years. Infants who underwent treatment more frequently showed abnormal results on several aspects of visual function. Presence of nystagmus appeared to increase the risk for abnormal visual function and neurodevelopmental outcome.

Spinal cord demyelination in children: A diagnostic challenge in neuropaediatrics for a good outcome.

BACKGROUND: Biotinidase deficiency (BTD) is an autosomal recessive inborn error of metabolism provoking progressive biotin depletion, which causes, in turn, multiple carboxylase deficiency. Its infantile onset is characterized by intractable seizures associated with lethargy, psychomotor regression, hypotonia, feeding and respiratory problems, and cutaneous abnormalities. CASE DESCRIPTION: We describe a 52-month-old female whose clinical and neuroradiological pictures were consistent with myelopathy, which is generally more frequent in older patients, as well as with symptoms of an infantile onset of biotinidase deficiency, revealed at 17 months. RESULTS: A biochemical biotinidase test revealed a profound deficiency of biotinidase detecting a 10% residual enzymatic activity, which led to the diagnosis of BTD. Gene sequencing revealed a compound heterozigous mutation (c.454A > C/c.1612C > T). CONCLUSION: Our findings suggest that even if myelopathy is uncommonly reported in BTD, and generally occurs in older children, its presence in childhood-onset floppiness should always be considered as a possible marker for an atypical presentation of BTD. Although, until recently, BTD myelopathy was believed to be prevalent in older children, a spinal cord involvement has also been described in at least nine cases in early infancy. Thus, another early diagnosis suggests that myelopathy may be more frequent than previously thought, and it is probably underdiagnosed because spinal MRI is not always routinely performed on these children. Early recognition of BTD disease is important as it would lead to prompt treatment, preventing irreversible brain damage and increasing the chances of complete recovery.

A wearable video-oculography based evaluation of saccades and respective clinical correlates in patients with early onset ataxia.

BACKGROUND: Friedreich Ataxia (FRDA) and other inherited chronic ataxias (CAs) are common causes of early onset ataxias (EOA), a group of conditions still lacking effective therapies and biomarkers. Ocular saccades are considered a reliable paradigm of motor control, useful to track the functioning of underlying neural networks and serving as potential markers for neurological diseases. NEW METHOD: A non-invasive video-oculography device (EyeSeeCam) was used to test saccadic parameters (latency, amplitude, duration, velocity) and peak velocity/amplitude ratio ("main sequence") in pediatric patients with FRDA, CAs and healthy controls, providing correlations with standard clinical scores. RESULTS: Pattern of saccadic features differed between CA and FRDA. The main sequence analysis was impaired respectively in vertical saccades in CA, and in horizontal saccades in FRDA. In CA, the amplitude of vertical saccades was reduced, and the size inversely correlated with the Scale for the assessment and rating of ataxia (SARA) score. In FRDA the amplitude of horizontal saccades directly correlated with SARA score. COMPARISON WITH EXISTING METHOD: EyeSeeCam allowed testing saccades easily and quickly even in pediatric patients with EOA. CONCLUSIONS: The pattern of saccadic impairment differed between FRDA and CAs, resulting a prominent involvement of vertical saccades in CA and of horizontal ones in FRDA, which respectively correlated with SARA score. Since such differences may reflect distinct pathophysiological substrates, saccades emerged as a potential source of biomarkers in EOAs. Availability of handy tools, such as EyeSeeCam, may facilitate future research in this field.

Early neurodevelopmental characterization in children with cobalamin C/defect.

Cobalamin C (cblC) defect is the most common inherited disorder of cobalamin metabolism. Developmental delay, behavioral problems, and maculopathy are common, but they have not been systematically investigated. The aim of this study was to define early neurodevelopment in cblC patients and the possible contribution of different factors, such as mode of diagnosis, age at diagnosis, presence of brain lesions and epilepsy. Children up to the age of 4 years with a visual acuity ≥1/10 were evaluated using the Griffiths' Mental Development Scales. Eighteen children were enrolled (age range 12-48 months). Four were diagnosed by newborn screening (NBS); in the others mean age at diagnosis was 3.5 months (range 0.3-18 months). Eight had seizures: three in the first year, and five after the second year of life. Fourteen had brain lesions on magnetic resonance imaging (MRI). Neurovisual assessment evidenced low visual acuity (<3/10) in 4/18. NBS diagnosed patients had higher general and subquotients neurodevelopmental scores, normal brain MRI, and no epilepsy. The others showed a progressive reduction of the developmental quotient with age and language impairment, which was evident after 24 months of age. Our findings showed a progressive neurodevelopmental deterioration and a specific fall in language development after 24 months in cblC defect. The presence of brain lesions and epilepsy was associated with a worst neurodevelopmental outcome. NBS, avoiding major disease-related events and allowing an earlier treatment initiation, appeared to have a protective effect on the development of brain lesions and to promote a more favorable neurodevelopment.

Corticospinal tract damage in HHH syndrome: a metabolic cause of hereditary spastic paraplegia.

BACKGROUND: Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare disorder of urea cycle characterized by progressive pyramidal and cerebellar dysfunction, whose pathophysiology is not yet fully understood. Here we describe the spectrum of the long fibers involvement in HHH syndrome, attempting a correlation between clinical, electrophysiological and neuro-radiological data. METHODS: Nine HHH patients were longitudinally evaluated by clinical examination, neurophysiological assessment including motor (MEPs), somato-sensory evoked potentials (PESS) and nerve conduction velocity (NCV), brain and spinal cord MRI RESULTS: All patients had pyramidal dysfunction and 3/9 an overt spastic paraplegia. Mild to moderate cerebellar signs were found in 7/9, intellectual disability in 8/9. At lower limbs, MEPs resulted abnormal in 7/8 patients and PESS in 2/8; peripheral sensory-motor neuropathy was found in 1/9. MRI documented atrophic changes in supra-tentorial brain regions in 6/9 patients, cerebellum in 6/9, spinal cord in 3/7. CONCLUSIONS: A predominant corticospinal dysfunction is evident in HHH syndrome, along with milder cerebellar signs, intellectual disability of variable degree and rare peripheral neuropathy. Phenotypical similarities with other disorders affecting the urea cycle (argininemia and pyrroline-5-carboxylate synthetase deficiency) suggest possible common mechanisms contributing in the maintenance of the corticospinal tract integrity. HHH syndrome phenotype largely overlaps with complex Hereditary Spastic Paraplegias (HSPs), in the list of which it should be included, emphasizing the importance to screen all the unsolved cases of HSPs for metabolic biomarkers.

Phenotype, treatment practice and outcome in the cobalamin-dependent remethylation disorders and MTHFR deficiency: Data from the E-HOD registry.

AIM: To explore the clinical presentation, course, treatment and impact of early treatment in patients with remethylation disorders from the European Network and Registry for Homocystinurias and Methylation Defects (E-HOD) international web-based registry. RESULTS: This review comprises 238 patients (cobalamin C defect n = 161; methylenetetrahydrofolate reductase deficiency n = 50; cobalamin G defect n = 11; cobalamin E defect n = 10; cobalamin D defect n = 5; and cobalamin J defect n = 1) from 47 centres for whom the E-HOD registry includes, as a minimum, data on medical history and enrolment visit. The duration of observation was 127 patient years. In 181 clinically diagnosed patients, the median age at presentation was 30 days (range 1 day to 42 years) and the median age at diagnosis was 3.7 months (range 3 days to 56 years). Seventy-five percent of pre-clinically diagnosed patients with cobalamin C disease became symptomatic within the first 15 days of life. Total homocysteine (tHcy), amino acids and urinary methylmalonic acid (MMA) were the most frequently assessed disease markers; confirmatory diagnostics were mainly molecular genetic studies. Remethylation disorders are multisystem diseases dominated by neurological and eye disease and failure to thrive. In this cohort, mortality, thromboembolic, psychiatric and renal disease were rarer than reported elsewhere. Early treatment correlates with lower overall morbidity but is less effective in preventing eye disease and cognitive impairment. The wide variation in treatment hampers the evaluation of particular therapeutic modalities. CONCLUSION: Treatment improves the clinical course of remethylation disorders and reduces morbidity, especially if started early, but neurocognitive and eye symptoms are less responsive. Current treatment is highly variable. This study has the inevitable limitations of a retrospective, registry-based design.