L-2-hydroxyglutaric aciduria: three Australian cases

Loss of function variants in L2HGDH gene causing L-2-hydroxyglutaric aciduria

BACKGROUND

L-2-Hydroxyglutaric aciduria (L2HGA) is a rare progressive neurometabolic disorder with variable clinical presentation including cerebellar ataxia, psychomotor retardation, seizures, macrocephaly and speech problems. In this study, we aimed at identifying the genetic cause in two unrelated families suspected with L2HGA.

METHODS

Exome sequencing was performed on two patients from family 1 with suspected L2HGA. MLPA analysis was carried out on the index patient of family 2 to detect deletions/duplications in the L2HGDH gene. Sanger sequencing was carried out to validate the identified variants and to confirm segregation of the variants in the family members.

RESULTS

In family 1, a novel homozygous variant c.1156C > T resulting in a nonsense mutation p.Gln386Ter was identified in the L2HGDH gene. The variant segregated with autosomal recessive inheritance in the family. In family 2, a homozygous deletion of exon 10 in the L2HGDH gene was identified in the index patient using MLPA analysis. PCR validation confirmed the presence of the deletion variant in the patient which is not present in the unaffected mother or an unrelated control.

CONCLUSION

This study identified novel pathogenic variants in the L2HGDH gene in patients with L2HGA. These findings contribute to the understanding of the genetic basis of L2HGA and highlight the importance of genetic testing for diagnosis and genetic counseling of affected families.

Intraventricular Glioblastoma Multiforme in A Child with L2-Hydroxyglutaric Aciduria

L2-hydroxyglutaric aciduria (L2-HGA) is a rare neurometabolic disease characterized by accumulation of L2-hydroxyglutarate (L2-HG), a potential oncometabolite resulting in significant lifetime risk for cerebral tumors. Herein, we present a case of intraventricular glioblastoma multiforme (GBM) in a 16-year-old child with L2-HGA who presented with rapid functional decline and persistent vomiting. The tumor was completely resected, and the patient remained well at 2-year follow-up. Clinicians should be aware of the usual insidious nature of the disease. Rapid deterioration is unusual and should raise the suspicion of tumor development. This case also illustrates the importance of surveillance neuroimaging in patients with L2-HGA. To the best of our knowledge, only 1 case of GBM has been reported and it was sited in the temporal lobe, unlike the unusual intraventricular location in our case.

Cerebral neoplasms in L-2 hydroxyglutaric aciduria: 3 new cases and meta-analysis of literature data

SUMMARY

Increasing evidence suggests that patients with L2-HGA have a predisposition to cerebral neoplasms. This may be related to the pathologic accumulation of L2-HG because high amounts of 2-HG have been found in brain neoplasms that have IDH1 mutations. Our experience, on the basis of 11 previously unreported cases of L2-HGA, 3 of which developed cerebral neoplasms during the course of the disease, also supports an association between L2-HGA and cerebral neoplasms. We conducted a meta-analysis of published data, and we identified 295 patients (including our 11 patients) with L2-HGA. In 14 patients, the metabolic disorder was associated with cerebral neoplasms, suggesting an approximately 5% prevalence rate of CNS neoplasms in patients with L2-HGA; nonetheless, it may still be an underestimate. L2-HGA is an important disease "model" that provides further evidence to support the recently proposed pathogenetic role of 2-HG in the development of cerebral neoplasms.

Isocitrate dehydrogenase 1/2 mutational analyses and 2-hydroxyglutarate measurements in Wilms tumors

BACKGROUND

L-2-Hydroxyglutaric aciduria (L-2-HGA) is an uncommon inborn error of metabolism, in which the patients are predisposed to develop brain tumors. Elevated levels of D-2-hydroxyglutarate have been demonstrated with malignant gliomas and myeloid leukemias associated with somatic mutations of the genes encoding NADP(+)-dependent isocitrate dehydrogenases (IDH1 and IDH2, respectively). Recently, we noted a Wilms tumor in a child with L-2-HGA. Given the accumulating evidence that both enantiomers of 2-hydroxyglutarate are associated with cellular transformation, we investigated if sporadic Wilms tumors are associated with IDH1 or IDH2 mutations or with elevated levels of 2-hydroxyglutarate.

PROCEDURE

We retrieved 21 frozen Wilms tumor tissues. In 20 cases, we sequenced exon 4 and flanking intronic regions of IDH1 and IDH2. In all 21 cases, we measured 2-hydroxyglutarate levels by liquid chromatography-tandem mass spectrometry.

RESULTS

We did not find mutations at the hot spots IDH1 codon 132 or IDH2 codon 172. Two cases (1 with favorable histology and 1 with unfavorable histology) showed heterozygous change c.211G>A (p.Val71Ile) in IDH1, a change previously reported as a mutation but listed as a single nucleotide polymorphism in the NCBI SNP database. We did not find increased levels of 2-hydroxygluatric acid in any sample.

CONCLUSIONS

Our results suggest that IDH1 codon 132 or IDH2 codon 172 mutations or elevated 2-hydroxyglutarate levels do not play a role in the biology of sporadic Wilms tumors. The significance of heterozygous change c.211G>A (p.Val71Ile) in IDH1, seen in two tumors, is not clear.

Papillary thyroid carcinoma shows elevated levels of 2-hydroxyglutarate

Elevated levels of D: -2-hydroxyglutarate (D: -2-HG) occur in gliomas and myeloid leukemias associated with mutations of IDH1 and IDH2. L: -2-Hydroxyglutaric aciduria, an inherited metabolic disorder, predisposes to brain tumors. Therefore, we asked whether sporadic cancers, without IDH1 or IDH2 hot-spot mutations, show elevated 2-hydroxyglutarate levels. We retrieved 15 pairs of frozen papillary thyroid carcinoma (PTC) and adjacent non-neoplastic thyroid, and 14 pairs of hyperplastic nodule (HN) and adjacent non-hyperplastic thyroid. In all lesions, exon 4 sequencing confirmed the absence of known mutations of IDH1 and IDH2. We measured 2-hydroxyglutarate by liquid chromatography-tandem mass spectrometry. Compared to normal thyroid, PTCs had significantly higher D: -2-HG and L: -2-hydroxyglutarate (L: -2-HG) levels, and compared to HNs, PTCs had significantly higher D: -2-HG levels. D: -2-HG/L: -2-HG levels were not significantly different between HNs and normal thyroid. Further studies should clarify if elevated 2-hydroxyglutarate in PTC may be useful as cancer biomarker and evaluate the role of 2-hydroxyglutarate in cancer biology.

Wilms tumor in a child with L-2-hydroxyglutaric aciduria

We report a male infant with L-2-hydroxyglutaric aciduria and Wilms tumor. L-2-hydroxyglutaric aciduria is a rare, autosomal-recessive, inborn error of metabolism characterized by a variable degree of progressive encephalopathy. Of the fewer than 100 cases reported in the literature, at least 9 patients have developed tumors of the central nervous system. To our knowledge, the present case is the 1st example of an extracranial tumor associated with L-2-hydroxyglutaric aciduria. This observation potentially widens the tumor spectrum in this metabolic disorder and may lead to further insight into the relationship between L-2-hydroxyglutaric acid and cellular transformation.

An overview of L-2-hydroxyglutarate dehydrogenase gene (L2HGDH) variants: a genotype-phenotype study

L-2-Hydroxyglutaric aciduria (L2HGA) is a rare, neurometabolic disorder with an autosomal recessive mode of inheritance. Affected individuals only have neurological manifestations, including psychomotor retardation, cerebellar ataxia, and more variably macrocephaly, or epilepsy. The diagnosis of L2HGA can be made based on magnetic resonance imaging (MRI), biochemical analysis, and mutational analysis of L2HGDH. About 200 patients with elevated concentrations of 2-hydroxyglutarate (2HG) in the urine were referred for chiral determination of 2HG and L2HGDH mutational analysis. All patients with increased L2HG (n=106; 83 families) were included. Clinical information on 61 patients was obtained via questionnaires. In 82 families the mutations were detected by direct sequence analysis and/or multiplex ligation dependent probe amplification (MLPA), including one case where MLPA was essential to detect the second allele. In another case RT-PCR followed by deep intronic sequencing was needed to detect the mutation. Thirty-five novel mutations as well as 35 reported mutations and 14 nondisease-related variants are reviewed and included in a novel Leiden Open source Variation Database (LOVD) for L2HGDH variants (http://www.LOVD.nl/L2HGDH). Every user can access the database and submit variants/patients. Furthermore, we report on the phenotype, including neurological manifestations and urinary levels of L2HG, and we evaluate the phenotype-genotype relationship.

Glutaric aciduria type II [corrected] and brain tumors: a case report and review of the literature

Heritable diseases associated with childhood tumors are sometimes defined as a probable etiologic factor or a coincidence. First of all, we must know the actual number of patients. Herein a case with medulloblastoma associated with glutaric aciduria type II [corrected] is reported for this purpose. A 5-year-old boy was admitted with nausea, vomiting, and lethargy. In medical history, consanguinity and siblings with mental-motor retardation and epilepsy are remarkable. Growth retardation, macrocephaly, lethargy, tremor, bilateral nistagmus, and papilledema were prominent features in physical examination. Noncontrast computed tomography of the brain showed a hyper dense mass in the cerebellar vermis. Gross total resection was made and the histopathology of the tumor was medulloblastoma. Besides medical history and physical findings, radiologic white matter changes in the subcortical, periventricular regions, bilateral basal ganglia, and caudate nuclei in magnetic resonance images other than tumor led us to investigate the child for glutaric aciduria type II [corrected]. The level of the 2-OH glutaric acid was determined as being 12-fold high in the urine. Chemo-radiotherapy was performed after surgery. Our case was the third patient with medulloblastoma in the literature and is still alive with no evidence of the disease 19 months after the initial diagnosis.

Sudden unexpected death in an infant with L-2-hydroxyglutaric aciduria

Inherited metabolic disorders are the cause of a small but significant number of sudden unexpected deaths in infancy. We report a girl who suddenly died at 11 months of age, during an intercurrent illness. Autopsy showed spongiform lesions in the subcortical white matter, in the basal ganglia, and in the dentate nuclei. Investigations in an older sister with developmental delay, ataxia, and tremor revealed L-2-hydroxyglutaric aciduria and subcortical white matter changes with hyperintensity of the basal ganglia and dentate nuclei at brain magnetic resonance imaging. Both children were homozygous for a splice site mutation in the L2HGDH gene. Sudden death has not been reported in association with L-2-hydroxyglutaric aciduria so far, but since this inborn error of metabolism is potentially treatable, early diagnosis may be important.

L-2-Hydroxyglutaric aciduria: pattern of MR imaging abnormalities in 56 patients

PURPOSE

To describe the pattern of magnetic resonance (MR) imaging abnormalities in l-2-hydroxyglutaric aciduria (L2HGA) and to evaluate the correlation between imaging abnormalities and disease duration.

MATERIALS AND METHODS

MR images in 56 patients (30 male, 26 female; mean age +/- standard deviation, 11.9 years +/- 8.5) with genetically confirmed L2HGA were retrospectively reviewed, with institutional review board approval and waiver of informed consent. At least one complete series of transverse T2-weighted images was available for all patients. The images were evaluated by using a previously established scoring list. The correlation between MR imaging abnormalities and disease duration was assessed (Mann-Whitney or Kruskal-Wallis test).

RESULTS

The cerebral white matter (WM) abnormalities preferentially affected the frontal and subcortical regions. The abnormal subcortical WM often had a mildly swollen appearance (37 patients). Initially, the WM abnormalities were at least partially multifocal (32 patients). In patients with longer disease duration, the WM abnormalities became more confluent and spread centripetally, but the periventricular rim remained relatively spared (41 patients). The mean disease duration in patients with WM atrophy (14.8 years) was significantly longer (P = .001) than that in patients without atrophy (6.7 years). Bilateral involvement of the globus pallidus (55 patients), caudate nucleus (56 patients), and putamen (56 patients) was seen at all stages. The cerebellar WM was never affected. The dentate nucleus was involved bilaterally in 55 of 56 patients.

CONCLUSION

L2HGA has a distinct highly characteristic pattern of MR imaging abnormalities: a combination of predominantly subcortical cerebral WM abnormalities and abnormalities of the dentate nucleus, globus pallidus, putamen, and caudate nucleus. With increasing disease duration, WM abnormalities and basal ganglia signal intensity abnormalities become more diffuse and cerebral WM atrophy ensues.

Hydroxyglutaric aciduria and malignant brain tumor: a case report and literature review

L -2-Hydroxyglutaric aciduria (L -2-OHGA) is a rare autosomal recessive inherited encephalopathy. This inborn error, characterized by psychomotor retardation, progressive ataxia and typical magnetic resonance imaging findings, presents in early infancy. To make a definitive diagnosis, an anomalous accumulation of L -2-hydroxyglutaric acid must be detected in body fluids. Here, we present a 17-year-old boy with L: -2-OHGA who developed an anaplastic ependymoma during the course of this disease. We also present a literature review including seven other patients who developed malignant brain tumors during the course of L -2-OHGA. This correlation may indicate a possible increased risk of brain tumors among patients with L -2-hydroxyglutaric aciduria.

L-2-hydroxyglutaric aciduria: characterisation of the molecular defect in a spontaneous canine model

l-2-hydroxyglutaric aciduria (l-2-HGA) is a neurometabolic disorder that produces a variety of clinical neurological deficits, including psychomotor retardation, seizures and ataxia. The biochemical hallmark of l-2-HGA is the accumulation of l-2-hydroxyglutaric acid (l-2-HG) in cerebrospinal fluid, plasma and urine. Mutations within the gene L2HGDH (Entrez Gene ID 79944) on chromosome 14q22 encoding L-2-hydroxyglutaric acid dehydrogenase have recently been shown to cause l-2-HGA in humans. Using a candidate gene approach in an outbred pet dog population segregating l-2-HGA, the causal molecular defect was identified in the canine homologue of L2HGDH and characterised. DNA sequencing and pedigree analysis indicate a common founder effect in the canine model. The canine model shares many of the clinical and MRI features of the disease in humans and represents a valuable resource as a spontaneous model of l-2-HGA.

Hemiconvulsion-hemiplegia-epilepsy syndrome as a presenting feature of L-2-hydroxyglutaric aciduria

L-2-hydroxyglutaric aciduria was diagnosed in a 9-month-old female infant after a complex febrile convulsion with subsequent transient left-sided hemiplegia. The symptoms were consistent with acute hemiconvulsion-hemiplegia-epilepsy syndrome. Magnetic resonance imaging (MRI) of the brain revealed distinct white-matter abnormalities in the bifrontal and bioccipital periventricular area and increased signal intensity in the lenticular, caudate, and dentate nuclei, consistent with L-2-hydroxyglutaric aciduria. Increased concentrations of L-2-hydroxyglutaric acid were detected in the urine, plasma, and cerebrospinal fluid. The patient was homozyous for the p.Lys81Glu (c.241A>G) missense mutation in the L-2-HGA gene, confirming the diagnosis of L-2-hydroxyglutaric aciduria. Acute hemiconvulsion-hemiplegia-epilepsy syndrome has not been reported as a presenting feature in L-2-hydroxyglutaric aciduria. In patients with prolonged or complicated febrile seizures such as hemiconvulsion-hemiplegia-epilepsy syndrome, L-2-hydroxyglutaric aciduria should be included in the differential diagnosis, especially in children with concomitant macrocephaly.

L-2-Hydroxyglutaric aciduria: identification of a mutant gene C14orf160, localized on chromosome 14q22.1

l-2-Hydroxyglutaric aciduria (l-2-HGA) is characterized by progressive deterioration of central nervous system function including epilepsy and macrocephaly in 50% of cases, and elevated levels of l-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid (CSF). Nuclear magnetic resonance imaging shows distinct abnormalities. We report the identification of a gene for l-2-HGA aciduria (MIM 236792) using homozygosity mapping. Nine homozygous mutations including three missense mutations, two nonsense mutations, two splice site mutations and two deletions were identified in the gene C14orf160, localized on chromosome 14q22.1, in 21 patients from one non-consanguineous and 14 consanguineous Turkish families. We propose to name the gene duranin. Duranin encodes a putative mitochondrial protein with homology to FAD-dependent oxidoreductases. The functional role of this enzyme in intermediary metabolism in humans remains to be established.

L-2-Hydroxyglutaric aciduria presenting as status epilepticus

L-2-Hydroxyglutaric aciduria (L-2-HGA) is a rare organic aciduria with a slowly progressive course regarding CNS involvement. We present a 13.5-year-old female patient who presented at the Emergency Department with a generalized status epilepticus, which promptly responded to intravenous phenytoin. CT and MRI demonstrated subcortical white matter alterations. The neurological examination revealed mild mental retardation, macrocephaly and ataxic gait with cerebellar signs. Repeated urinary organic acid analysis demonstrated increased excretion of 2-hydroxyglutaric acid which was of the L-configuration. The constellation of macrocephaly in a patient with mental retardation, cerebellar tract involvement and subcortical white matter signal alterations on MRI should alert the physician to the possibility of L-2-HGA. Although rare, epileptic seizures or even status epilepticus can be among the presenting symptoms in organic acidurias with a slow course, such as L-2-HGA.

Chiral liquid chromatography tandem mass spectrometry in the determination of the configuration of 2-hydroxyglutaric acid in urine

D-2-Hydroxyglutaric aciduria and L-2-hydroxyglutaric aciduria are two distinct inherited metabolic diseases. The accurate diagnosis of the exact disorder relies on the determination of the configuration of the enantiomers, either D-2-hydroxyglutaric acid or L-2-hydroxyglutaric acid excreted in excess in urine of patients. The enantiomeric chiral separation of 2-hydroxyglutaric acid was achieved using a ristocetin A glycopeptide antibiotic silica gel bonded column. The chiral column was interfaced with a tandem mass spectrometer for the purpose of specifically detecting the eluting 2-hydroxyglutaric acid. Tandem mass spectrometry was employed using an electrospray ion source in the negative ion mode. Three parent-to-daughter transitions under collision-induced dissociation conditions were used to detect only 2-hydroxyglutaric acid. The two forms of the compound were satisfactorily separated with almost baseline resolution at 4.95 and 5.5 min. Three known patients with 2-hydroxyglutaric aciduria were identified to have L-2-hydroxyglutaric aciduria. The method is simple, selective, rapid, and free from interference.

D-2-Hydroxyglutaric aciduria: biochemical marker or clinical disease entity?

D-2-Hydroxyglutaric aciduria has been observed in patients with extremely variable clinical symptoms, creating doubt about the existence of a disease entity related to the biochemical finding. An international survey of patients with D-2-hydroxyglutaric aciduria was initiated to solve this issue. The clinical history, neuroimaging, and biochemical findings of 17 patients were studied. Ten of the patients had a severe early-infantile-onset encephalopathy characterized by epilepsy, hypotonia, cerebral visual failure, and little development. Five of these patients had a cardiomyopathy. In neuroimaging, all patients had a mild ventriculomegaly, often enlarged frontal subarachnoid spaces and subdural effusions, and always signs of delayed cerebral maturation. In all patients who underwent neuroimaging before 6 months, subependymal cysts over the head or corpus of the caudate nucleus were noted. Seven patients had a much milder and variable clinical picture, most often characterized by mental retardation, hypotonia, and macrocephaly, but sometimes no related clinical problems. Neuroimaging findings in 3 patients variably showed delayed cerebral maturation, ventriculomegaly, or subependymal cysts. Biochemical findings included elevations of D-2-hydroxyglutaric acid in urine, plasma, and cerebrospinal fluid in both groups. Cerebrospinal fluid gamma-aminobutyric acid was elevated in almost all patients investigated. Urinary citric acid cycle intermediates were variably elevated. The conclusion of the study is that D-2-hydroxyglutaric aciduria is a distinct neurometabolic disorder with at least two phenotypes.

L-2-Hydroxyglutaric aciduria: clinical, biochemical and magnetic resonance imaging in six Portuguese pediatric patients

We present clinical, biochemical and cranial magnetic resonance imaging data of six pediatric patients with L-2-hydroxyglutaric aciduria. All the children have the same ethic origin and lived in the northern area of Portugal. Our findings reinforce the described phenotype of this rare metabolic disease with mental deficiency, severe cerebellar dysfunction, mild extrapyramidal and pyramidal symptoms, progressive macrocephaly and seizures. Magnetic resonance imaging revealed subcortical leukoencephalopathy, cerebellar atrophy and signal changes in the putamina and dentate nuclei. These were similar to those of the previous reports in all patients. The urinary excretion of L-2-hydroxyglutaric acid was variably increased in all patients. The other persistent biochemical abnormality was hyperlysinemia. We have found a strong correlation between the severity of the clinical manifestations and the extension of the lesions in the neuroimaging studies. There was no correlation between the clinical findings and the amount of urinary excretion of L-2-hydroxyglutaric acid. We report the second case in the literature of a cerebral thalamic tumor in L-2-hydroxyglutaric aciduria; neuropathological examination of the surgical biopsy demonstrated a diffuse fibrillary astrocytoma.

D-2-hydroxyglutaric aciduria: hypotonia, cortical blindness, seizures, cardiomyopathy, and cylindrical spirals in skeletal muscle

An infant girl was demonstrated to have D-2-hydroxyglutaric aciduria, the fifth case described and the first with muscle biopsy of this rare organic aciduria that differs clinically and genetically from the more common L-2-hydroxyglutaric aciduria. Her clinical features included mildly dysmorphic facies, developmental delay, generalized hypotonia, myoclonic seizures, cortical blindness, and dilated cardiomyopathy requiring treatment. Muscle biopsy demonstrated only excessive glycogen histochemically, but ultrastructural examination revealed subsarcolemmal cylindrical spirals and normal mitochondria. Because of the metabolism of D-2-hydroxyglutaric aciduria, we regard valproic acid as contraindicated in the treatment of epilepsy in this disease.

2-Hydroxyglutaric aciduria: a case report on an infant with the D-isomeric form with review of the literature

We report on an infant with D-2-hydroxyglutaric aciduria, who presented with severe seizures and developmental delay. We reviewed the literature for 2-hydroxyglutaric aciduria and found six other patients with the D-isomer and 24 patients with the L-isomer. Although the clinical spectrum of this inborn error of metabolism is variable, the clinical course of the D-form seems to be more severe than this of the L-form.

Clinical and magnetic resonance imaging features of L-2-hydroxyglutaric acidemia: report of three cases in comparison with Canavan disease

We report three cases of L-2-hydroxyglutaric acidemia and three cases of Canavan disease. The L-2-hydroxyglutaric acidemia cases are the first biochemically proven Turkish cases. Magnetic resonance imaging findings in the cases and similarities between the two diseases are emphasized. Both diseases are characterized by predominant subcortical white-matter involvement and dentate nuclei lesions with variable basal ganglia involvement. Canavan disease differs from L-2-hydroxyglutaric acidemia by the presence of typical brainstem involvement.

L-2-Hydroxyglutaric aciduria: neuropathological correlations and first report of severe neurodegenerative disease and neonatal death

L-2-Hydroxyglutaric aciduria is a rare organic aciduria associated with neurological and particularly cerebellar abnormalities. These abnormalities developed in childhood or later in all previously described patients. We report a more severe form of L-2-hydroxyglutaric aciduria in which an infant presented shortly after birth with hypotonia, apnoea, and seizures, leading to death in the perinatal period. Computerized tomography scans of the brain at 1 day and 2 weeks of age showed abnormal low density of the cerebellum. Examination of the brain showed brainstem and cerebellar atrophy with neuronal loss and gliosis in an olivopontocerebellar distribution. The diagnosis of L-2-hydroxyglutaric aciduria should be considered in any non-dysmorphic newborn with progressive neurological abnormalities and CNS imaging suggesting low density and size of the cerebellum. The diagnostic consideration is based initially on clinical findings. Conventional urine organic acid analysis reveals the presence of 2-hydroxyglutaric aciduria. Specific diagnosis requires methodologies which distinguish the L- from the D-isomer.

Leukoencephalopathy with swelling in children and adolescents: MRI patterns and differential diagnosis

In children, several neurological disorders are characterised by spongiform leukoencephalopathy. MRI of the brain typically shows white matter swelling, but does not enable differentiation of the various underlying disorders. The aim of this article is optimisation of the diagnostic value of MRI in leukoencephalopathy accompanied by swelling. MRI-based inclusion criteria were met by 20 patients in our database. The images were analysed using a detailed scoring list. In 13 of the 20 patients the clinical diagnosis was known (11 definite and 2 probable diagnoses). Characteristic MRI abnormalities could be defined in these patients. Of the 7 patients without a diagnosis, 5 had identical MRI abnormalities: diffuse hemisphere swelling and typical cysts in frontoparietal subcortical white matter and the tips of the temporal lobes. The clinical picture was also similar in these patients, suggesting a similar disease.

Clinical and MRI findings in a case of D-2-hydroxyglutaric aciduria

We report the 3rd case in the literature of a 3-year-old boy with D-2-hydroxyglutaric (D-2-HG) aciduria, who presented primarily generalized hypotonia and feeding difficulty during the neonatal period, with eventual development of generalized myoclonic seizures. Gas chromatographic analysis of urinary organic acids showed persistent excretion of D-2-HG. The clinical manifestations are quite similar to those of the 2nd reported case with D-2-HG aciduria. Serial MRI performed 1 year and 2 1/2 years after birth demonstrated bilateral symmetrical periventricular lesions in the parieto-occipital white matter, which might reflect the cortical blindness in our patient.

Leukoencephalopathy with swelling and a discrepantly mild clinical course in eight children

An identical syndrome of cerebral leukoencephalopathy and megalencephaly with infantile onset was discovered in 8 children, including 2 siblings. Neurological findings were initially normal or near normal, despite megalencephaly and magnetic resonance imaging (MRI) evidence of severe white matter affection. Slowly progressive ataxia and spasticity developed, while intellectual functioning was preserved for years after onset of the disorder. MRI characteristics included diffuse abnormality in signal intensity and swelling of the cerebral hemispheral white matter with cyst-like spaces in the frontoparietal and anterior-temporal subcortical areas. MR spectra were relatively mildly abnormal. Screening for inborn errors, especially those that cause either megalencephaly or white matter disease or both was negative. A distinguishing feature of the present disorder is the apparently severe abnormality of the cerebral white matter as demonstrated by MRI, which contrasts with the remarkably slow course of functional deterioration.

D-2-hydroxyglutaric aciduria

Hydroxyglutaric aciduria is detected by gas chromatographic-mass spectrometric analysis, and the D and L forms are quantified by chemical ionization with deuterated internal standards. Patients have recently been described who accumulate the D form, and they appear to be quite different from those with the more common L form. Experience is reported with three patients and an animal model with D-2-hydroxyglutaric aciduria. The phenotype appears to include mental retardation, macrocephaly, hypotonia, seizures, and involuntary movements, although neurologic and systemic manifestations of the disorder varied considerably between individual patients, even within the same family.