3-Methylglutaconic aciduria in "optic atrophy plus"

Oxidative Stress in Antibiotic Toxic Optic Neuropathy Mimicking Acute LHON in a Patient with Exacerbation of Cystic Fibrosis

The striking similarity of disc edema without leakage on fluorescein angiography, which is pathognomonic of Leber hereditary optic neuropathy (LHON), was present in a patient with cystic fibrosis with antibiotic toxic optic neuropathy. This similarity suggested the common effect of oxidative stress on retinal ganglion cells in inherited mitochondrial and antibiotic optic neuropathies. We present the case of a patient with advanced cystic fibrosis on chronic antibiotic treatment who experienced a rapid painless bilateral visual decline over a course of a few weeks. At examination, his corrected visual acuity was reduced to 0.3 in both eyes, with dyschromatopsia and central scotoma. The appearance of the fundus resembled the typical clinical features of acute LHON with hyperemic optic discs and tortuous vessels with no dye leakage from the optic discs on fluorescein angiography. Ganglion cell layer loss was seen on optic coherence tomography, with all findings pointing to LHON. Genetic testing did not reveal any LHON-specific mutations. After extended genetic testing, a heterozygous variant c.209C>T in the OPA3 gene on chromosome 19, g.46032648G>A, classified as a variant of unknown significance, was also found. After discontinuing antibiotics and general improvements in his health, surprisingly, his visual function completely improved. Later, he also received a bilateral lung transplant that further improved his general condition, and his vision remained normal. Excluding LHON, the transient optic neuropathy in our patient could be mainly due to antibiotic toxicity of linezolid and ciprofloxacin, which have been linked to mitochondrial dysfunction and advanced cystic fibrosis with hypoxic status. We suggest the possibility that patients with cystic fibrosis may be more prone to developing mitochondrial optic neuropathy, especially with additional risk factors such as chronic antibiotic therapy, which affect mitochondrial function, and can perhaps serve as a model for LHON.

Biallelic Optic Atrophy 1 (OPA1) Related Disorder-Case Report and Literature Review

Dominant optic atrophy (DOA), MIM # 605290, is the most common hereditary optic neuropathy inherited in an autosomal dominant pattern. Clinically, it presents a progressive decrease in vision, central visual field defects, and retinal ganglion cell loss. A biallelic mode of inheritance causes syndromic DOA or Behr phenotype, MIM # 605290. This case report details a family with Biallelic Optic Atrophy 1 (OPA1). The proband is a child with a severe phenotype and two variants in the OPA1 gene. He presented with congenital nystagmus, progressive vision loss, and optic atrophy, as well as progressive ataxia, and was found to have two likely pathogenic variants in his OPA1 gene: c.2287del (p.Ser763Valfs*15) maternally inherited and c.1311A>G (p.lIle437Met) paternally inherited. The first variant is predicted to be pathogenic and likely to cause DOA. In contrast, the second is considered asymptomatic by itself but has been reported in patients with DOA phenotype and is presumed to act as a phenotypic modifier. On follow-up, he developed profound vision impairment, intractable seizures, and metabolic strokes. A literature review of reported biallelic OPA1-related Behr syndrome was performed. Twenty-one cases have been previously reported. All share an early-onset, severe ocular phenotype and systemic features, which seem to be the hallmark of the disease.

Neuro-Ophthalmic Phenotype of OPA3

BACKGROUND

Type III 3-methylglutaconic aciduria (OPA 3) is a neuro-ophthalmologic syndrome consisting of early-onset bilateral optic atrophy. Since Costeff described the phenotype of 19 patients in 1989, several reports described approximately 50 patients, but most of them lack details about neuro-ophthalmic phenotype. Our aim was to characterize the clinical neuro-ophthalmic phenotype of this syndrome.

METHODS

Nine patients underwent meticulous visual function history and medical documents' review. Results of best-corrected visual acuity (VA), color vision, visual field (VF), ocular motility, pupillary reaction, slit-lamp, and dilated fundus examinations were recorded. Optical coherence tomography (OCT) was performed whenever possible.

RESULTS

The average VA was 1.4 ± 0.8 logarithm of the minimum angle of resolution. Poor vision was the presenting symptom in 5 patients. Six patients had decreased VA and variable degrees of optic atrophy. Humphrey VF testing of 7 patients revealed generalized depression in 5 and a cecocentral defect in 2. All patients demonstrated dysmetric saccades. Four patients had strabismus, 3 with exotropia, and one with esotropia. Seven patients had nystagmus. Ocular motility abnormality is possibly the result of cerebellar atrophy that was found in MRI studies of our patients. OCT of the retina was possible in 6 patients and revealed retinal nerve fiber layer (RNFL) thinning as well as average retinal thinning. Three patients, in whom ganglion cell layer-inner plexiform layer (IPL) measurement was possible, also showed diffused thinning.

CONCLUSIONS

This study compiled data regarding neuro-ophthalmic manifestation of OPA 3 Type III patients. Contrary to established literature, poor vision was the presenting symptom in only 50% of our patients. This is the first report of OCT findings in 3MGA patients. The results demonstrated diffused thinning of the RNFL and ganglion cell complex-IPL with correlation to VA, which is in contrast to OPA1 patients in whom the most severe thinning is at the level of the papillomacular bundle. Average retinal thinning was identified at second and third decades of life, possibly resulting from early ganglion cell loss. These results may contribute to visual prognosis, and OCT may help monitor experimental therapies.

A novel mutation in the SERAC1 gene correlates with the severe manifestation of the MEGDEL phenotype, as revealed by whole-exome sequencing

The condition 3-methylglutaconic aciduria (3-MGA) with deafness, encephalopathy and Leigh-like (MEGDEL) syndrome, also known as 3-MGA IV, is one of a group of five rare metabolic disorders characterized by mitochondrial dysfunction, resulting in a series of phenotypic abnormalities. It is a rare, recessive inherited disorder with a limited number of cases reported worldwide; hence, it is important to study each case to understand its genetic complexity. An impaired activity of serine active site-containing protein 1 (SERAC1), caused by mutations, leads to defects in phosphatidylglycerol remodelling, which is important for mitochondrial function and intracellular cholesterol trafficking. In the present study, the patients (two male siblings of consanguineous Turkish parents) were analysed, whose multisystem dysfunctions, including an elevated 3-MGA concentration in early age, hearing loss and Leigh-like syndrome as determined by MRI, were consistent with MEGDEL syndrome. A novel mutation in the SERAC1 gene, in the upstream lipase domain, c.1015G>C (p.Gly339Arg) mutation located on exon 10 of the SERAC1, was identified and predicted to cause protein dysfunction. Furthermore, the results pointed towards a possible association between this mutation and the severity of MEGDEL syndrome.

Costeff syndrome: clinical features and natural history

Costeff syndrome (CS) is a rare autosomal-recessive neurological disorder, which is known almost exclusively in patients of Iraqi Jewish descent, manifesting in childhood with optic atrophy, ataxia, chorea and spastic paraparesis. Our aim was to study the clinical spectrum of CS and natural history using a cross-sectional study design. Consecutive patients with CS were recruited to the study. Patients were diagnosed based on clinical features, along with elevated urinary levels of methylglutaconic and methylglutaric acid, and by identification of the disease-causing mutation in the OPA3 gene in most. All patients were examined by a neurologist and signs and symptoms were rated. 28 patients with CS (16 males, 21 families, age at last observation 28.6 ± 16.1 years, range 0.5-68 years) were included. First signs of neurological deficit appeared in infancy or early childhood, with delayed motor milestones, choreiform movements, ataxia and visual disturbances. Ataxia and chorea were the dominant motor features in childhood, but varied in severity among patients and did not seem to worsen with age. Pyramidal dysfunction appeared later and progressed with age (r = 0.71, p < 0.001) leading to spastic paraparesis and marked gait impairment. The course of neurological deterioration was slow and the majority of patients could still walk beyond the fifth decade. While visual acuity seemed to deteriorate, it did not correlate with age. CS is a rare neurogenetic disorder that causes serious disability and worsens with age. Spasticity significantly increases over the years and is the most crucial determinant of neurological dysfunction.

Two novel compound heterozygous mutations in OPA3 in two siblings with OPA3-related 3-methylglutaconic aciduria

OPA3-related 3-methylglutaconic aciduria, or Costeff Optic Atrophy syndrome, is a neuro-ophthalmologic syndrome of early-onset bilateral optic atrophy and later-onset spasticity, and extrapyramidal dysfunction. Urinary excretion of 3-methylglutaconic acid and of 3-methylglutaric acid is markedly increased. OPA3-related 3-methylglutaconic aciduria is due to mutations in the OPA3 gene located at 19q13.2-13.3. Here we describe two siblings with novel compound heterozygous variants in OPA3: c.1A>G (p.1M>V) in the translation initiation codon in exon 1 and a second variant, c.142+5G>C in intron 1. On cDNA sequencing the c.1A>G appeared homozygous, indicating that the allele without the c.1A>G variant is degraded. This is likely due to an intronic variant; possibly the IVS1+5 splice site variant. The older female sibling initially presented with motor developmental delay and vertical nystagmus during her first year of life and was diagnosed subsequently with optic atrophy. Her brother presented with mildly increased hip muscle tone followed by vertical nystagmus within the first 6 months of life, and was found to have elevated urinary excretion of 3-methylglutaconic acid and 3-methylglutaric acid, and optic atrophy by 1.5 years of age. Currently, ages 16 and 7, both children exhibit ataxic gaits and dysarthric speech. Immunofluorescence studies on patient's cells showed fragmented mitochondrial morphology. Thus, though the exact function of OPA3 remains unknown, our experimental results and clinical summary provide evidence for the pathogenicity of the identified OPA3 variants and provide further evidence for a mitochondrial pathology in this disease.

Optic neuropathy in methylmalonic acidemia: the role of neuroprotection

We report the case of a patient with an optic neuropathy induced by neurotoxicity in the setting of methylmalonic acidemia. The patient responded with a significant and long-term improvement in visual acuity, perimetry, and chromatic function after a neuroprotective treatment with vitamin E and coenzyme Q10 was started. Coenzyme Q10 levels had been proven to be normal before starting treatment. This case report is particularly important because it describes a possible treatment for optic neuropathy in methylmalonic patients. Although the response might be, in part, specific to the individual, it suggests the existence of a cause-effect relationship between the treatment undergone by our patient and the improvement in her visual acuity. To date, no other treatments with beneficial effects have been reported for the few optic neuropathies caused by methylmalonic acidemia. Further studies should determine the applicability of coenzyme Q10 and vitamin E for the treatment of optic neuropathies in methylmalonic acidemia.

OPA3, mutated in 3-methylglutaconic aciduria type III, encodes two transcripts targeted primarily to mitochondria

3-Methylglutaconic aciduria type III (3-MGCA type III), caused by recessive mutations in the 2-exon gene OPA3, is characterized by early-onset bilateral optic atrophy, later-onset extrapyramidal dysfunction, and increased urinary excretion of 3-methylglutaconic acid and 3-methylglutaric acid. Here we report the identification of a novel third OPA3 coding exon, the apparent product of a segmental duplication event, resulting in two gene transcripts, OPA3A and OPA3B. OPA3A deficiency (as in optic atrophy type 3) causes up-regulation of OPA3B. OPA3 protein function remains unknown, but it contains a putative mitochondrial leader sequence, mitochondrial sorting signal and a peroxisomal sorting signal. Our green fluorescent protein tagged OPA3 expression studies found its localization to be predominantly mitochondrial. These findings thus place the cellular metabolic defect of 3-MGCA type III in the mitochondrion rather than the peroxisome and implicate loss of OPA3A rather than gain of OPA3B in disease etiology.

Late onset optic neuropathy in methylmalonic and propionic acidemia

PURPOSE

To describe 3 cases of late-onset bilateral optic neuropathy with visual dysfunction in patients with organic acidemia.

DESIGN

Retrospective case series.

METHODS

A total of 3 subjects, a 16-year-old male with methylmalonic acidemia (MMA), a 21-year-old male with MMA, and a 20-year-old female with propionic acidemia (PA), are included in this series. Comparison of the patients' clinical course, ophthalmologic exam, and testing are discussed. The outcome measures include visual acuity (VA), fundus appearance, visual fields, brain imaging, and genetic testing.

RESULTS

All 3 subjects had late-onset severe bilateral VA loss with bilateral optic nerve pallor, central or cecocentral scotomas on visual field testing, and negative diagnostic workups for other causes of bilateral optic neuropathy.

CONCLUSIONS

Patients with organic acidemia may develop late-onset bilateral optic neuropathy with visual dysfunction despite lifelong propiogenic amino acid restriction and dietary supplementation.

Familial Behr syndrome-like phenotype with autosomal dominant inheritance

Behr syndrome is an autosomal recessive disease characterized by early-onset ataxia, optic atrophy and other signs such as pyramidal tract dysfunction. Autosomal dominant inheritance has also been described. In this case report we present a family pedigree of patients with an inherited autosomal dominant Behr syndrome-like phenotype emphasizing their clinical and neuroimaging features.

Optic atrophies in metabolic disorders

Optic nerve involvement in metabolic disorders often results from apoptosis of cells that form or support the optic nerve, the retinal ganglion cell (RGC) axons, the myelin-forming oligodendrocytes, or the supporting vascular system. Given their high energy demands and the long course of their axons, RGCs are particularly sensitive to intracellular metabolic defects. Defects in energy metabolism, formation of reactive oxygen species, and storage of metabolites can all cause apoptosis of RGCs, decreased myelin formation of oligodendrocytes and increased pressure on the optic nerve. Clinically, the loss of RGC axons manifests as pale optic nerves. In general, the ophthalmologist can identify the underlying cause of an optic atrophy by careful examination, neuro-imaging, and family history. In some cases, however, the diagnosis proves elusive. In these instances, and especially when optic atrophy is accompanied by other systemic involvement, a metabolic disorder should be considered. Here, we review the underlying mechanisms of optic atrophy and its significance in metabolic disorders. Early identification of optic atrophy aids the diagnosis and subsequent management of the underlying condition, including anticipation of symptoms, genetic counseling, and possible therapeutic interventions. For many metabolic disorders, molecular testing is available.

Hereditary optic neuropathies

AIMS

To provide a clinical update on the hereditary optic neuropathies.

METHODS

Review of the literature.

RESULTS

The hereditary optic neuropathies comprise a group of disorders in which the cause of optic nerve dysfunction appears to be hereditable, based on familial expression or genetic analysis. In some hereditary optic neuropathies, optic nerve dysfunction is typically the only manifestation of the disease. In others, various neurologic and systemic abnormalities are regularly observed.

CONCLUSION

The most common hereditary optic neuropathies are autosomal dominant optic atrophy (Kjer's disease) and maternally inherited Leber's hereditary optic neuropathy. We review the clinical phenotypes of these and other inherited disorders with optic nerve involvement.

Optic nerve atrophy in propionic acidemia

OBJECTIVE

Propionic acidemia is a rare metabolic disorder that is diagnosed in the early neonatal period. The disorder is characterized by life-threatening ketoacidosis, lethargy, failure to thrive, and developmental delay. Herein we report the ocular findings in a prospective series of six patients with propionic acidemia.

DESIGN

Prospective case series.

PARTICIPANTS

Six children (three male and three female) between the ages of 2 and 10 years with propionic acidemia who were examined at Children's Hospital Los Angeles.

METHODS

A complete ophthalmic examination was performed on each of the six children. The examination included visual acuity testing, ocular motility, anterior segment examination, and funduscopic evaluation. Emphasis was placed on the function of the optic nerve and on the appearance of the optic disc, looking for possible atrophic changes.

MAIN OUTCOME MEASURES

The clinical appearance of the optic disc and evidence of optic neuropathy.

RESULTS

Optic nerve atrophy was present exclusively in all of the male patients in the series; none of the female patients demonstrated any detectable impairment of optic nerve function. The optic nerve atrophy was symmetric and age dependent and varied from moderate to severe. There were no other anterior or posterior segment abnormalities, other than one case of unilateral morning glory syndrome, diagnosed at birth. There was no correlation between metabolic control and the development and progression of optic nerve atrophy.

CONCLUSIONS

Males with propionic acidemia have moderate to severe bilateral optic atrophy.

3-Methylglutaconic aciduria type III in a non-Iraqi-Jewish kindred: clinical and molecular findings

Type III 3-methylglutaconic aciduria (MGA) (MIM 258501) consists of early bilateral optic atrophy, later development of spasticity, extrapyramidal dysfunction and occasionally cognitive deficits, and urinary excretion of 3-methylglutaconic acid and 3-methylglutaric acid. The presence of the disorder in an Iraqi-Jewish genetic isolate led to mapping of the OPA3 gene to chromosome 19q13.2-q13.3, followed by isolation of the gene itself. OPA3 consists of two exons and codes for a peptide of 179 amino acids. Iraqi-Jewish patients with type III MGA are homozygous for a splice site founder mutation in OPA3 (IVS1-1G>C) which abolishes mRNA expression in fibroblasts. Here we report a novel mutation in OPA3 (320-337del) in a Kurdish-Turkish patient with optic atrophy and 3-methylglutaconic and 3-methylglutaric aciduria, previously carrying the diagnosis of type IV MGA. We conclude that type III MGA occurs in patients of non-Iraqi-Jewish ancestry, and should be considered in patients with type IV MGA that have optic atrophy and ataxia.

Type III 3-methylglutaconic aciduria (optic atrophy plus syndrome, or Costeff optic atrophy syndrome): identification of the OPA3 gene and its founder mutation in Iraqi Jews

Type III 3-methylglutaconic aciduria (MGA) (MIM 258501) is a neuro-ophthalmologic syndrome that consists of early-onset bilateral optic atrophy and later-onset spasticity, extrapyramidal dysfunction, and cognitive deficit. Urinary excretion of 3-methylglutaconic acid and of 3-methylglutaric acid is increased. The disorder has been reported in approximately 40 patients of Iraqi Jewish origin, allowing the mapping of the disease to chromosome 19q13.2-q13.3, by linkage analysis. To isolate the causative gene, OPA3, we sequenced four genes within the critical interval and identified, in the intronic sequence of a gene corresponding to cDNA clone FLJ22187, a point mutation that segregated with the type III MGA phenotype. The FLJ22187-cDNA clone, which we identified as the OPA3 gene, consists of two exons and encodes a peptide of 179 amino acid residues. Northern blot analysis revealed a primary transcript of approximately 5.0 kb that was ubiquitously expressed, most prominently in skeletal muscle and kidney. Within the brain, the cerebral cortex, the medulla, the cerebellum, and the frontal lobe, compared to other parts of the brain, had slightly increased expression. The intronic G-->C mutation abolished mRNA expression in fibroblasts from affected patients and was detected in 8 of 85 anonymous Israeli individuals of Iraqi Jewish origin. Milder mutations in OPA3 should be sought in patients with optic atrophy with later onset, even in the absence of additional neurological abnormalities.

A case of 3-methylglutaconic aciduria misdiagnosed as cerebral palsy

3-Methylglutaconic aciduria is a rare hereditary metabolic disorder characterized by increased urinary excretion of 3-methylglutaconic and 3-methylglutaric acids. Four clinical forms are recognized. This study presents the case of a 5-year-old male with type IV 3-methylglutaconic aciduria, initially diagnosed as "static encephalopathy." The slow evolution and other clinical characteristics, together with cerebral magnetic resonance imaging (MRI) findings, eventually directed the diagnosis to organic aciduria that was confirmed by urine test. This study proposes that the clinical criteria for childhood cerebral palsy should be rigorously respected; neuroimaging studies, particularly MRI, should be conducted to confirm the diagnosis, especially in atypical cases.

Childhood optic atrophy

PURPOSE

To determine the causes, and relative incidence of the common causes, of optic nerve atrophy in children under 10 years old and to compare prevalent aetiologies with those given in previous studies.

METHODS

The Wilmer Information System database was searched to identify all children, diagnosed between 1987 and 1997 with optic atrophy, who were under 10 years old at diagnosis. The medical records of these children were reviewed retrospectively

RESULTS

A total of 272 children were identified, Complications from premature birth were the most frequent aetiology of optic atrophy (n = 44, 16%); 68% of these premature infants having a history of intraventricular haemorrhage. Tumour was the second most common aetiology (n = 40, 15%). The most frequent tumour was pilocytic astrocytoma (50%), followed by craniopharyngioma (17%). Hydrocephalus, unrelated to tumour, was the third most common aetiology (n = 26, 10%). In 114 cases (42%), the cause of optic atrophy became manifest in the perinatal period and/or could be attributed to adverse events in utero. A cause was not determined in 4% of cases.

CONCLUSIONS

In the last decade, prematurity and hydrocephalus appear to have become important causes of optic atrophy in childhood. This trend is probably the result of improved survival of infants with extremely low birth weight.

3-Methylglutaconic aciduria and hypermethioninaemia in a child with clinical and neuroradiological findings of Leigh disease

We report on a child with a clinical and neuroradiological picture consistent with Leigh disease and an unusual association of isolated hypermethioninaemia and 3-methylglutaconic aciduria. A low-methionine diet normalized both plasma methionine and urine 3-methylglutaconic acid; a methionine-loading test led to significant increase of both metabolites. In the skin fibroblasts the activity of 3-methylglutaconyl-CoA hydratase was essentially normal. No explanation of this uncommon association of hypermethioninaemia and glutaconic aciduria is available. The possibility of a common transporter for 3-methylglutaconic acid and methionine is an attractive hypothesis.

18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in type IV 3-methylglutaconic aciduria: clinical and MRI correlations

The clinical, 18fluorodeoxyglucose positron emission tomography (18FDG PET) and the magnetic resonance imaging (MRI) brain scan characteristics of four patients diagnosed to have 3-methylglutaconic aciduria were reviewed retrospectively. The disease has a characteristic clinical pattern. The initial presentations were developmental delay, hypotonia, and severe failure to thrive. Later, progressive encephalopathy with rigidity and quadriparesis were observed, followed by severe dystonia and choreoathetosis. Finally, the patients became severely demented and bedridden. The 18FDG PET scans showed progressive disease, explaining the neurological status. It could be classified into three stages. Stage I: absent 18FDG uptake in the heads of the caudate, mild decreased thalamic and cerebellar metabolism. Stage II: absent uptake in the anterior half and posterior quarter of the putamina, mild-moderate decreased uptake in the cerebral cortex more prominently in the parieto-temporal lobes. Progressive decreased thalamic and cerebellar uptake. Stage III: absent uptake in the putamina and severe decreased cortical uptake consistent with brain atrophy and further decrease uptake in the cerebellum. The presence of both structural and functional changes in the brain, demonstrated by the combined use of MRI and 18FDG PET scan, with good clinical correlation, make the two techniques complementary in the imaging evaluation of 3-methylglutaconic aciduria.

Ineffectiveness of oral coenzyme Q10 supplementation in 3-methylglutaconic aciduria, type 3

Coenzyme Q10 was administered under placebo controlled blinded crossover conditions to six subjects suffering from type 3 3-methylglutaconic aciduria ('optic atrophy plus'), following a report of benefit. Despite attainment of high plasma levels of coenzyme Q10, no clinical benefit was observed and there was no diminution of urinary excretion of 3-methylglutaconic acid.

Organic acidurias and related abnormalities

Organic acid analysis is a powerful technique in the diagnosis of inborn errors of metabolism. Since the development of the technique over twenty-five years ago, it has evolved into a sophisticated and powerful method and is an essential tool in the diagnosis of the organic acidurias. The chemistry and biochemistry of organic acids, as well as sample preparation, instrumentation, and many aspects of the more commonly used methods for the analysis of these compounds, are reviewed. The biochemical and clinical characteristics of each of the primary organic acidurias are described. In addition, the various noninherited causes of secondary organic acidurias that lead to the excretion of abnormal organic acids are also described, and ways of differentiating primary from secondary causes are discussed.

CT and MR of the brain in the diagnosis of organic acidemias. Experiences from 107 patients

The results of CT and/or MRI of the brain in 107 patients with different types of organic acidemia are presented. The CSF spaces were wide in more than two-thirds of the patients, in 46 slightly-to-moderately and in 26 markedly-to-severely dilated. Marked widening of the operculae was found in all 5 patients with glutaric acidemia type 1, but open opercula was also found in other organic acidemias. White matter changes were found in about half the patients, in 28 mildly-to-moderately pronounced, in another 28 marked or severe. Basal ganglia or central pathway pathology was seen in a total of 34 patients, i.e. 32%. These changes in 25 patients involved the caudate and/or lentiform nuclei: in 14 cases the T2 signal was increased and volume loss was present, in 9 cases increased T2 signal with preserved volume was found (in one of these the changes were transient). In 2 patients, both with ethylmalonic aciduria (cause unknown), only small high T2 spots were seen in the caudate heads and the putamina. In 4 patients, all suffering from methylmalonic acidemia, only the globus pallidus was affected. In 3 patients, all with beta-ketothiolase deficiency, high T2 intensity changes were seen only in the postero-lateral putamina. The remaining 8 patients represent a variety of different locations of lesions. The CT or MRI findings in many patients with organic acidemias should alert the radiologist that a neurometabolic disorder may be present; in some cases the location and appearance of the lesions may even suggest the correct diagnosis.

Neurophysiologic correlates of organic acidemias: a survey of 107 patients

The files of 107 patients with 19 different types of organic acidemia were reviewed retrospectively. Approximately 50% of the patients had abnormal electroencephalogram (EEG) at the time of initial study. In patients who had serial studies, the EEG deteriorated in 38% and improved in 15%. The predominant EEG abnormality encountered was slowing of the background activity in various degrees. Focal or generalized paroxysmal activity occurring in conjunction with slow background activity indicated a poor prognosis. Brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), and somatosensory evoked potentials (SEP) were analyzed. The VEP was abnormal in 44%, BAEP in 39%, and SEP in 29% of the patients. Given the magnitude and frequency by which neurophysiological abnormalities occur in organic acidemias, neurophysiology testing provides complementary functional information and has an important place in the clinical work-up of these diseases.

3-Methylglutaconic aciduria: ten new cases with a possible new phenotype

3-Methylglutaconic aciduria is an organic aciduria with diverse phenotypic presentations. In more than half of the cases it is a 'neurologic or silent organic aciduria', and, except for one subtype, the biochemical defect is unknown. This report describes 10 new patients. Four of them presented with early global neurologic involvement and arrested development. They rapidly became demented, developed myoclonus or tonic-clonic seizures, spastic quadriplegia, deafness and blindness, and died. Three had acidosis and hypoglycemia neonatally; later, myoclonus and deafness, and eventually severe mental retardation and spastic quadriplegia developed. One patient died. In three children who presented with sudden onset of extrapyramidal tract symptoms, with or without optic atrophy, the clinical presentation was significantly different from that described either for 'unspecified' type or for Costeff syndrome. All three patients showed clinical improvement soon after treatment with coenzyme Q.

3-Methylglutaconic aciduria in the Iraqi-Jewish 'optic atrophy plus' (Costeff) syndrome

Eleven new patients of Iraqi-Jewish origin with bilateral optic atrophy, neurological abnormalities ('optic atrophy plus' syndrome) and 3-methylglutaconic aciduria (type III) are described. Clinical abnormalities in decreasing order of frequency were bilateral optic atrophy, extrapyramidal signs, spasticity, ataxia, dysarthria and cognitive deficit. An association with age was found only for spasticity. Spasticity, extrapyramidal signs and optic atrophy frequently led to major disability, in contrast to ataxia, dysarthria and cognitive deficit. The combined excretion of 3-methylglutaconic and 3-methylglutaric acid ranged between 9 and 187 mmol/mol creatinine. The primary enzymatic defect possibly may reside in the mitochondrial respiratory chain.

Neurologic genetic diseases of Jewish people

Three important dominantly-inherited neurological diseases were discovered to be particularly common among various Jewish ethnic groups. For idiopathic torsion dystonia (ITD), previously thought to be recessively transmitted among Ashkenazi Jews, we have established an autosomal dominant mode of inheritance. This finding resulted from a country-wide survey of ITD in Israel and its subsequent genetic analysis. In Creutzfeldt-Jakob disease (CJD) the focus among Libyan Jews was previously thought to be related to culinary habits; a point mutation of the prion-protein gene was first described by us. The factors leading to the preservation of these disadvantageous genes in the communities are however unknown. Genetic analysis shows reduced penetrance in ITD and age-related expression in CJD. Factors leading to the expression of the genes were looked for. Data for ITD suggest that laterality of onset depends on motor dominance. Data on anticipation are presented. Factors possibly involved in the expression of the CJD codon 200 mutation are also discussed. A focus of myotonic dystrophy was documented among Yemenite Jews. The preservation of this disadvantageous, dominantly-inherited gene (which leads to diminished reproductive abilities), was found to be social rather than biological, related to reduced age of marriage and number of offspring in this ethnic group. These data show an interaction between genetic and other biological and external factors in the expression of these three diseases.