Modified Frameless Stereotactic System for Intracerebral Delivery of Viral Vector in Young Children.

BACKGROUND: Stereotaxic surgery for viral vector delivery in young children is highly challenging because of their small cranial size, thin and fragile skull, and deformity of the skull or brain after prolonged bed ridden condition. OBJECTIVE: To develop a modified frameless stereotactic system especially suitable for intracerebral delivery of viral vector in young children for accurate localization of intracerebral targets during stereotactic surgery. METHODS: A modified frameless stereotactic system was developed for intracerebral delivery of viral vector in pediatric patients with congenital enzyme deficiency. Localization markers and a stereotactic stabilizer were designed specifically for surgery in pediatric patients, and this equipment is used along with a pre-existing frameless stereotactic and computer-assisted planning and navigation system. RESULTS: We applied this modified frameless stereotactic system to treat 10 children with aromatic L-amino acid decarboxylase deficiency. CONCLUSION: It is potentially suitable for stereotactic functional neurosurgery in pediatric patients as young as 1 yr and 8 mo of age.

Gene therapy improves brain white matter in aromatic l-amino acid decarboxylase deficiency.

OBJECTIVE: Children with aromatic l-amino acid decarboxylase (AADC) deficiency suffer from severe motor dysfunction. Restoration of dopamine levels in the putamen by gene therapy has led to significant improvement in motor function. This study explored brain structure changes in patients. METHODS: Brain diffusion tensor imaging (DTI) was performed before and 12 months after gene therapy. Whole-brain tract-specific analysis was performed to assess white matter microstructural integrity. RESULTS: In the 8 patients (aged 1.67-8.42 years) enrolled in the study, gene therapy did not affect macroscopic structure. DTI before gene therapy revealed lower total mean fractional anisotropy (FA) values in patients than in the age-matched pretreatment controls (p = 0.017; median difference = -0.0136; 95% confidence interval [CI] [-0.0319, -0.0126]). After gene therapy, total mean FA increased (p = 0.012, median difference = 0.0211, 95% CI [0.0094, 0.0456]), and the values in the patients were not different from the age-matched posttreatment controls. Increase in total mean FA after gene therapy in patients was correlated with their increase in motor score (r = 0.846; p = 0.008), but was inversely correlated with their ages at the time of gene therapy (r = -0.754; p = 0.031). Corticospinal tracts, and the thalamic radiation and callosal fibers involving motor function, improved after gene therapy. INTERPRETATION: Improvement in the microstructural integrity of white matter tracts is associated with the improvement in motor function following gene therapy. Ann Neurol 2019;85:644-652.

The Value of 1H-MRS and MRI in Combined Methylmalonic Aciduria and Homocystinuria.

OBJECTIVE: The aims of this study were to describe the brain magnetic resonance imaging (MRI) features of methylmalonic aciduria and homocystinuria and to evaluate the additional value of H-MRS. PATIENTS AND METHODS: Twenty-eight children with methylmalonic aciduria and homocystinuria were included in this study. The control group included 21 healthy children. All the cases underwent MRI and H-MRS before treatment. We measured the N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and myoinositol (mI) peaks in the basal ganglia regions. The NAA/Cr, Cho/Cr, mI/Cr, and NAA/Cho ratios were calculated. We also observed whether there were lactic acid peaks. RESULT: We identified that NAA/Cr and NAA/Cho significantly decreased in the basal ganglia and that 3 patients showed lactate peaks, but other metabolites were not significantly altered. Hydrocephalus and diffuse supratentorial white matter edema were the primary MR findings; 7 patients had thinning of the corpus callosum, and 2 patients had subdural hematoma. Six patients showed normal brain MRI findings. CONCLUSIONS: Methylmalonic aciduria and homocystinuria patients with metabolite changes in the basal ganglia demonstrate compromised neuronal integrity, and anerobic metabolism occurs in acute encephalopathic episodes. H-MRS is a useful tool for evaluating brain damage. Hydrocephalus and diffuse supratentorial white matter edema are the main MRI features.

Gene therapy improves motor and mental function of aromatic l-amino acid decarboxylase deficiency.

In patients with aromatic l-amino acid decarboxylase (AADC) deficiency, a decrease in catecholamines and serotonin levels in the brain leads to developmental delay and movement disorders. The beneficial effects of gene therapy in patients from 1 to 8 years of age with homogeneous severity of disease have been reported from Taiwan. We conducted an open-label phase 1/2 study of population including adolescent patients with different degrees of severity. Six patients were enrolled: four males (ages 4, 10, 15 and 19 years) and one female (age 12 years) with a severe phenotype who were not capable of voluntary movement or speech, and one female (age 5 years) with a moderate phenotype who could walk with support. The patients received a total of 2 × 1011 vector genomes of adeno-associated virus vector harbouring DDC via bilateral intraputaminal infusions. At up to 2 years after gene therapy, the motor function was remarkably improved in all patients. Three patients with the severe phenotype were able to stand with support, and one patient could walk with a walker, while the patient with the moderate phenotype could run and ride a bicycle. This moderate-phenotype patient also showed improvement in her mental function, being able to converse fluently and perform simple arithmetic. Dystonia disappeared and oculogyric crisis was markedly decreased in all patients. The patients exhibited transient choreic dyskinesia for a couple of months, but no adverse events caused by vector were observed. PET with 6-[18F]fluoro-l-m-tyrosine, a specific tracer for AADC, showed a persistently increased uptake in the broad areas of the putamen. In our study, older patients (>8 years of age) also showed improvement, although treatment was more effective in younger patients. The genetic background of our patients was heterogeneous, and some patients suspected of having remnant enzyme activity showed better improvement than the Taiwanese patients. In addition to the alleviation of motor symptoms, the cognitive and verbal functions were improved in a patient with the moderate phenotype. The restoration of dopamine synthesis in the putamen via gene transfer provides transformative medical benefit across all patient ages, genotypes, and disease severities included in this study, with the most pronounced improvements noted in moderate patients.10.1093/brain/awy331_video1awy331media15991361892001.

Hydrocephalus in cblC type methylmalonic acidemia.

Methylmalonic acidemia (MMA) is a typical type of organic acidemia caused by defects in methylmalonyl-CoA mutase or adenosyl-cobalamin synthesis. Hydrocephalus (HC), results from an imbalance between production and absorption of cerebrospinal fluid (CSF), causeing enlarged cerebral ventricles and increased intracranial pressure, is a condition that requires urgent clinical decision-making. MMA without treatment could result in brain damage. However, HC in MMA was rarely reported. In this study, 147 MMA were identified from 9117 high risk children by gas chromatography mass spectrometry (GC/MS) for organic acidurias screening in urine samples and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for amino acids detection in blood samples. Totally 10 cases with MMA and HC were determined by brain MRI/CT, as well as gene mutation testing either by high throughput sequencing or Sanger sequencing. Besides, homocysteine was also analyzed for the 10 MMA with HC. Out of them, 9 cases carry out compound heterozygous mutations or homozygous mutation in MMACHC gene, and 1 case has MUTmutation. The mutation c.609G > A in MMACHC was the most common in the cbl type patients. Although MMA has a high incidence in Shandong province of China, especially cblC type. All of the 10 patients were not correctly diagnosed before developing HC. As a result, when a child develops progressive and refractory HC, the screening for inherited metabolic diseases should be immediately conducted.

Malignant brain tumors in patients with glutaric aciduria type I.

Three young patients with glutaric aciduria type I (age 6-23 years) of different ethnic origins, treated for their metabolic disease since early childhood, presented with malignant central nervous system tumors. We recommend continuing clinical follow-up, including monitoring of neurological manifestations and neuroradiological findings, in all patients with glutaric aciduria type I beyond early childhood, especially if adherence to diet is poor or the treatment was not started neonatally.

Shunt surgery for early-onset severe hydrocephalus in methylmalonic acidemia: report on two cases and review of the literature.

OBJECT: Methylmalonic acidemia (MMA) with early-onset severe hydrocephalus is rare. In this paper, we described two cases of MMA with hydrocephalus and review the literature to elucidate the clinical features of the disease, treatment options, and follow-up results. METHODS: The PubMed and Embase databases were searched for clinical reports on MMA with severe hydrocephalus, and two unreported cases were presented to illustrate the clinical spectrum. RESULTS: Six cases of MMA with severe hydrocephalus were observed in the previous literature. Our two patients with severe hydrocephalus but not bulging fontanelle received a ventriculo-peritoneal shunt, and intracranial hypertension was confirmed in both cases during the operation. These patients' clinical symptoms significantly improved after the operation. CONCLUSIONS: Intracranial hypertension can exist in early-onset severe hydrocephalus in MMA, even if the bulging anterior fontanelle is not apparent. These patients could benefit from a ventriculo-peritoneal shunt.

γ-glutamyl transpeptidase deficiency caused by a large homozygous intragenic deletion in GGT1.

γ-Glutamyl transpeptidase deficiency (glutathionuria, OMIM 231950) is a rare disease, with only six patients reported in the literature, although this condition has probably been underdiagnosed due the difficulty to routinely analyze glutathione in clinical samples and to the fact that no genetic defect has been coupled to the disease so far. We report two siblings with mild psychomotor developmental delay and mild neurological symptoms, who presented a markedly increased excretion of glutathione in urine and a very low γ-glutamyl transpeptidase activity in serum. Whole-genome sequencing revealed the presence of a 16.9 kb homozygous deletion in GGT1, one of the genes encoding enzymes with γ-glutamyl transpeptidase activity in the human genome. Close analysis revealed the presence of a 13 bp insertion at the deletion junction. This is the first report of a genetic variant as the cause of glutathionuria. In addition, genetic characterization of the patients' parents and a healthy sibling has provided direct genetic evidence regarding the autosomal recessive nature of this disease.

Genotype-phenotype correlation in 18 Egyptian patients with glutaric acidemia type I.

Glutaric acidemia I (GAI) is an autosomal recessive metabolic disease caused by a deficiency of glutaryl-CoA dehydrogenase enzyme (GCDH). Patients with GAI are characterized by macrocephaly, acute encephalitis-like crises, dystonia and frontotemporal atrophy. In this study, we investigated 18 Egyptian patients that were diagnosed with GAI based on their clinical, neuroradiological, and biochemical profiles. Of the 18 patients, 16 had developmental delay and/or regression, dystonia was prominent in 75% of the cases, and three patients died. Molecular genetics analysis identified 14 different mutations in the GCDH gene in the 18 patients, of the 14 mutations, nine were missense, three were in the 3'-Untranslated Region (3'-UTR), one was nonsense, and one was a silent mutation. Four novel mutations were identified (c.148 T > A; p.Trp50Arg, c.158C > A; p.Pro53Gln, c.1284C > G; p.Ile428Met, and c.1189G > T; p.Glu397*) that were all absent in 300 normal chromosomes. The 3'-UTR mutation (c.*165A > G; rs8012), was the most frequent mutation observed (0.5; 18/36), followed by the most common mutation among Caucasian patients (p.Arg402Trp; rs121434369) with allele frequency of 0.36 (13/36), and the 3'-UTR mutation (c.*288G > T; rs9384, 0.22; 8/16). The p.Arg257Gln mutation was found with allele frequency of ~0.17 (6/36). The marked homozygosity observed in our patients is probably due to the high level of consanguinity that is observed in 100% of the cases. We used nine in silico prediction tools to predict the pathogenicity (SIFT, PhD-SNP, SNAP, Meta-SNP, PolyPhen2, and Align GVGD) and protein stability (I-Mutant2.0, Mupro, and istable) of the nine missense mutants. The mutant p.Arg402Trp was predicted to be most deleterious by all the six pathogenicity prediction tools and destabilizing by all the three-stability prediction tools, and highly conserved by the ConSurf server. Using the clinical, biochemical, family history of the 18 patients, and the in silico analysis of the missense mutations, our study showed a mix of conclusive and inconclusive genotype-phenotype correlations among our patient's cohort and suggests the usefulness of using various sophisticated computational analysis to be utilized for future variant classifications in the genetic clinics.

Benefits of Neuronal Preferential Systemic Gene Therapy for Neurotransmitter Deficiency.

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disease that impairs synthesis of dopamine and serotonin. Children with AADC deficiency exhibit severe motor, behavioral, and autonomic dysfunctions. We previously generated an IVS6+4A>T knock-in mouse model of AADC deficiency (Ddc(KI) mice) and showed that gene therapy at the neonatal stage can rescue this phenotype. In the present study, we extended this treatment to systemic therapy on young mice. After intraperitoneal injection of AADC viral vectors into 7-day-old Ddc(KI) mice, the treated mice exhibited improvements in weight gain, survival, motor function, autonomic function, and behavior. The yfAAV9/3-Syn-I-mAADC-treated mice showed greater neuronal transduction and higher brain dopamine levels than AAV9-CMV-hAADC-treated mice, whereas AAV9-CMV-hAADC-treated mice exhibited hyperactivity. Therefore, neurotransmitter-deficient animals can be rescued at a young age using systemic gene therapy, although a vector for preferential neuronal expression may be necessary to avoid hyperactivity caused by this treatment.

[Clinical investigation and genetic analysis of a Chinese family with glutaric acidemia type I].

OBJECTIVE: To review the clinical features of a families affected with glutaric acidemia type I (GA-1) and screen potential mutations in glutaryl-CoA dehydrogenase (GCDH) gene. METHODS: Clinical data of the patients and their family members was analyzed. Genomic DNA was extracted from peripheral blood samples. The 11 exons and flanking sequences of the GCDH gene were amplified with PCR and subjected to direct DNA sequencing. RESULTS: Two patients have manifested macrocephaly. Imaging analysis revealed arachnoid cyst and subdural effusion. The elder sister had encephalopathy crisis. The younger sister had significantly raised glutaric acid, whilst the elder sister was normal during the non-acute phase. Genetic analysis has revealed a homozygous c.1244-2A> C mutation of the GCDH gene in both patients. CONCLUSION: The clinical features and mutation of the GCDH gene have been delineated in a Chinese family affected with GA-1. The c.1244-2A> C mutation may be particularly common in the Chinese population.

Renal growth in isolated methylmalonic acidemia.

PURPOSE: We sought to predict renal growth based on clinical and metabolic parameters in patients with isolated methylmalonic acidemia, a group of disorders associated with chronic kidney disease. METHODS: Fifty patients with methylmalonic acidemia, followed from 2004 to 2011, were classified by molecular genetics and studied using a combined cross-sectional and longitudinal design that included renal ultrasound examinations, anthropometric measurements, and metabolic phenotyping. Renal length was compared with that of healthy controls and modeled to other clinical parameters using multiple-regression analyses. RESULTS: Comparisons with age-matched controls showed that renal length in subjects with methylmalonic acidemia was significantly decreased (P < 0.05). Stepwise regression modeling found that combinations of height, serum cystatin C, and serum methymalonic acid concentrations best predicted kidney size. The regression equations used to generate methylmalonic acidemia kidney nomograms were renal length (cm) = 6.79 + 0.22 × age for the controls and 6.80 + 0.09 × age for the methylmalonic acidemia cohort (P < 0.001; constant and slope). CONCLUSION: Renal length, reflective of kidney growth, significantly decreased in patients with methylmalonic acidemia over time as compared with controls and was predictable with select clinical parameters. Cystatin C and serum methylmalonic acid concentrations were highly correlated with smaller kidneys and decreased renal function in this patient population.

Pseudotumours of hepatic imaging.

The diagnosis of liver tumours with CT depends on differential attenuation coefficients and enhancement patterns. The sensitivity of CT in defining tumours is well established but there remain a variety of conditions that mimic these patterns, presenting a 'pseudotumour' appearance. A common illustrative example is hepatic steatosis, but less well recorded are the sphingolipidoses and intrahepatic arterioportal shunts, either post-traumatic or related to venous outflow block. Alpha-1-antitrypsin deficiency and hereditary tyrosinaemia provide examples in childhood.

Bilateral arachnoid cysts of the temporal fossa in four children with glutaric aciduria type I.

Glutaric aciduria type I is an uncommon inborn error of metabolism. It is a serious disease, often with a fatal outcome. This study reports the presence of bilateral temporal fluid collections, probably bilateral arachnoid cysts, in association with glutaric aciduria type I. The CT and, when available, MR studies from five patients with this disorder were reviewed. Four of the patients had findings consistent with bilateral arachnoid cysts of the temporal fossa. This is a rare occurrence, with only 11 such cases reported in the literature. The observed association between temporal fluid collections and glutaric aciduria type I suggests that patients with bilateral arachnoid cysts should be investigated for this metabolic disorder.

Hepatic imaging with computed tomography of chronic tyrosinaemia type 1.

Tyrosinaemia type 1 (fumaryl acetoacetase deficiency, hepato-renal tyrosinaemia) is a rare inborn error of metabolism which, in its chronic form, leads to cirrhosis in early childhood and subsequent development of hepatocellular carcinoma in a high proportion of cases. Imaging with computed tomography has an important role in assessing the progress of the liver disease and may be helpful in timing liver transplantation. The radiological features of seven cases are described and the implications discussed.

Cranial computerized tomography in dihydropteridine reductase deficiency.

Dihydropteridine reductase deficiency is a rare cause of hyperphenylalaninaemia, characterized by severe and progressive neurological impairment, despite early and accurate dietary control of plasma phenylalanine. We describe two girls, diagnosed at 17 and 14 months of age, respectively, and immediately treated with L-dopa, 5-hydroxytryptophan and carbidopa. In spite of an adequate dietary and pharmacological treatment, the clinical and neurological pictures progressively worsened. Repeated cranial computerized axial tomography scans showed degeneration of the white matter and, in one case, calcification of the basal ganglia. The possible association of this last finding with folate depletion is discussed.

Abnormalities of the liver and other organs.

The liver may undergo pathologic changes as a result of an overall disease process that also affects other organs. This article focuses on those diseases in which abnormalities of the liver are only one part of the process, and in which radiographic investigation of the liver is diagnostically important.