Supratentorial and pontine MRI abnormalities characterize recessive spastic ataxia of Charlevoix-Saguenay. A comprehensive study of an Italian series.

BACKGROUND AND PURPOSE: The autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset neurodegenerative disorder caused by mutations in the SACS gene. The disease, first described in Canadian families from Québec, is characterized by cerebellar ataxia, pyramidal tract involvement and peripheral neuropathy. METHODS: Analysis of SACS gene allowed the identification of 14 patients with ARSACS from 13 unrelated Italian families. Clinical phenotype, gene mutations and magnetic resonance imaging (MRI) findings were analysed. RESULTS: We found 16 novel SACS gene mutations, including a large in-frame deletion. The age at onset was in infancy, but one patient presented the first symptoms at age 32. Progression of the disease was variable, and increased muscle tone was mostly recognized in later stages. Structural MRI showed atrophy of the superior cerebellar vermis, a bulky pons exhibiting T2-hypointense stripes, identified as the corticospinal tract (CST), thinning of the corpus callosum and a rim of T2-hyperintensity around the thalami in 100% of cases. The presence of iron or other paramagnetic substances was excluded. Diffusion tensor imaging (DTI) revealed grossly over-represented transverse pontine fibres (TPF), which prevented reconstruction of the CST at this level (100% of cases). In all patients, significant microstructural alterations were found in the supratentorial white matter of forceps, cingulum and superior longitudinal fasciculus. CONCLUSIONS: Our findings further enlarge the genetic spectrum of SACS mutations and widen the study of clinical phenotype. MRI characteristics indicate that pontine changes and supratentorial abnormalities are diagnostic. The over-representation of TPF on DTI suggests a developmental component in the pathogenesis of the disease.

Early-onset LBSL: how severe does it get?

AIM: Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is known as a relatively mild leukoencephalopathy. We investigated the occurrence of severe variants of LBSL with extensive brain magnetic resonance imaging (MRI) abnormalities. METHOD: MRIs of approximately 3,000 patients with an unknown leukoencephalopathy were retrospectively reviewed for extensive signal abnormalities of the cerebral and cerebellar white matter, posterior limb of the internal capsule, cerebellar peduncles, pyramids, and medial lemniscus. Clinical data were retrospectively collected. RESULTS: Eleven patients fulfilled the MRI criteria (six males); six had DARS2 mutations. Clinical and laboratory findings did not distinguish between patients with and without DARS2 mutations, but MRI did. Patients with DARS2 mutations more often had involvement of structures typically affected in LBSL, including decussatio of the medial lemniscus, anterior spinocerebellar tracts, and superior and inferior cerebellar peduncles. Also, involvement of the globus pallidus was associated with DARS2 mutations. Earliest disease onset was neonatal; earliest death at 20 months. INTERPRETATION: This study confirms the occurrence of early infantile, severe LBSL, extending the known phenotypic range of LBSL. Abnormality of specific brainstem tracts and cerebellar peduncles are MRI findings that point to the correct diagnosis.

Hemophagocytic lymphohistiocytosis with neurological presentation: MRI findings and a nearly miss diagnosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare disease with rarer neurological presentation. When this occurs, diagnosis may be delayed. This report aims to call attention to clinical, laboratory, and radiological features that should prompt the correct diagnosis. A 13-year-old girl presented with progressive increase in intracranial pressure and ataxia. MRI showed a diffuse tumor-like swelling of the cerebellum with tonsillar herniation and patchy white matter post-contrast enhancement. Regression of swelling with steroids ruled out glioma and medulloblastoma, and brain lymphoma was considered. Diagnosis of HLH was reached 2 months after onset when uncontrolled fever and severe elevation of liver enzymes occurred. Two bone marrow biopsies were needed to demonstrate hemophagocytosis. Familial HLH was confirmed by perforin gene mutations. Bone marrow transplantation was performed. The early diagnosis of HLH may be life saving. Awareness of the disease is necessary to investigate its characteristic findings, thus avoiding a delay in diagnosis.

Identification of new mutations in the ETHE1 gene in a cohort of 14 patients presenting with ethylmalonic encephalopathy.

BACKGROUND: Ethylmalonic encephalopathy (EE) is a rare autosomal recessive metabolic disorder characterised by progressive encephalopathy, recurrent petechiae, acrocyanosis and chronic diarrhoea, with a fatal outcome in early in life. METHODS: 14 patients with EE were investigated for mutations in the ETHE1 gene. RESULTS: Of the 14 patients, 5 were found to carry novel mutations. CONCLUSIONS: This work expands our knowledge of the causative mutations of EE.

Genotype-phenotype correlation in five Pelizaeus-Merzbacher disease patients with PLP1 gene duplications.

Pelizaeus-Merzbacher disease (PMD) is an X-linked myelination disorder most frequently caused by duplication of a genomic segment of variable length containing the PLP1 gene. We studied five PMD male patients affected by the classic PMD form carrying a PLP1 gene duplication. On the basis of clinical and neuroradiological features, two of the five patients appeared to be the most severely affected. In order to establish a possible genotype-phenotype correlation, the extent of the duplication was determined in each patient and in the respective mother by quantifying the copy number of genomic markers surrounding the PLP1 gene by a real-time PCR-based approach. Duplications, ranging in size from 167-195 to 580-700 kb, were in the same genomic interval of the majority of the reported duplications. The extent of the duplicated genomic segments does not correlate with the clinical severity. Interestingly enough, each duplication had one of the two breakpoints in or near to low copy repeats (LCRs), supporting recent evidence concerning a possible role of LCRs in the generation of the duplications in PMD.

Effect of testosterone metabolites on ABC half-transporter relative gene expression in X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is an inherited neurodegenerative disorder associated with reduced very long-chain fatty acid beta-oxidation, mainly affecting the nervous system, the adrenal cortex and the testes. The clinical manifestations of hypogonadism, alopecia and the impairment of the enzyme 5alpha-reductase, which converts testosterone into dihydrotestosterone, clearly point to an involvement of androgens in this pathology. The disease is characterized by mutations in the ABCD1 gene, which codes for the peroxisomal ABC half-transporter ALDP, and by a broad range of clinical manifestations. The altered function of ALDP can be compensated by the overexpression of proteins belonging to the same family of ABC half-transporters. A promising therapeutic approach is represented by the activation of these proteins by specific agonists. In this study we evaluated the effect of the testosterone metabolite dihydrotestosterone (DHT) and 5alpha-androstan-3alpha,17beta-diol (3alpha-diol) on the expression of the ABC half-transporters encoded by the ABCD2 and ABCD3 genes, in fibroblasts drawn from controls and from two affected brothers. The two patients presented the same mutation in exon 9 but had different clinical manifestations, one patient being asymptomatic and the second one severely affected. When the cells were stimulated with testosterone metabolites, only the severely affected patient showed a significant increase in ABCD2 mRNA levels, while the ABCD3 expression remained unchanged in both patients.

Borderline mental development in a congenital disorder of glycosylation (CDG) type Ia patient with multisystemic involvement (intermediate phenotype).

CDG Ia (phosphomannomutase deficiency) has a wide clinical spectrum with the most severe affected patients having multisystemic disease in addition to severe nervous system involvement. We report a patient with CDG Ia and an intermediate phenotype due to mild neurological impairment and borderline cognitive abilities despite the occurrence of typical extraneurological symptoms. These included liver involvement, coagulopathy and failure to thrive with enteropathy. Genotype analyses showed that he was compound heterozygous for T237R/C241S mutations. This observation underlines that the CDG Ia clinical spectrum may include intraindividual variability that might reflect different degrees of glycosylation abnormalities among distinct body compartments. CDG Ia should be considered in cases of unexplained liver involvement and/or enteropathy in patients with mild developmental delay and subtle neurological signs.

A scale to monitor progression and treatment of mitochondrial disease in children.

Mitochondrial diseases affect all age groups, but those with childhood onset often seem to experience the greatest burden of disability. In some paediatric patients this can be explained by a cumulative disability acquired over many years. In others, additional factors, including the nature and severity of the molecular defect, must be considered. To date, no large-scale studies have attempted to document the natural history of paediatric mitochondrial disease. This is in part at least, because no assessment tool has been available to plot the temporal course of a disease with such a diverse clinical spectrum. This paper describes how a practical and semi-quantitative rating scale has been devised for children with mitochondrial disease, the Newcastle paediatric mitochondrial disease scale (NPMDS). The scale is multi-dimensional and reproducible, offering a tool through which mitochondrial disease progression can be objectively monitored. We anticipate that use of this tool will facilitate both longitudinal natural history studies and the assessment of future therapeutic interventions.

Novel mutations in COX15 in a long surviving Leigh syndrome patient with cytochrome c oxidase deficiency.

BACKGROUND: Isolated cytochrome c oxidase (COX) deficiency is usually associated with mutations in several factors involved in the biogenesis of COX. METHODS: We describe a patient with atypical, long surviving Leigh syndrome carrying two novel mutations in the COX15 gene, which encodes an enzyme involved in the biosynthesis of heme A. RESULTS: Only two COX15 mutated patients, one with severe neonatal cardiomyopathy, the other with rapidly fatal Leigh syndrome, have been described to date. In contrast, our patient had a slowly progressive course with no heart involvement. COX deficiency was mild in muscle and a normal amount of fully assembled COX was present in cultured fibroblasts. CONCLUSIONS: The clinical and biochemical phenotypes in COX15 defects are more heterogeneous than in other conditions associated with COX deficiency, such as mutations in SURF1.

Clinical and molecular findings in children with complex I deficiency.

Isolated complex I deficiency, the most frequent OXPHOS disorder in infants and children, is genetically heterogeneous. Mutations have been found in seven mitochondrial DNA (mtDNA) and eight nuclear DNA encoded subunits, respectively, but in most of the cases the genetic basis of the biochemical defect is unknown. We analyzed the entire mtDNA and 11 nuclear encoded complex I subunits in 23 isolated complex I-deficient children, classified into five clinical groups: Leigh syndrome, progressive leukoencephalopathy, neonatal cardiomyopathy, severe infantile lactic acidosis, and a miscellaneous group of unspecified encephalomyopathies. A genetic definition was reached in eight patients (35%). Mutations in mtDNA were found in six out of eight children with Leigh syndrome, indicating a prevalent association between this phenotype and abnormalities in ND genes. In two patients with leukoencephalopathy, homozygous mutations were detected in two different nuclear-encoded complex I genes, including a novel transition in NDUFS1 subunit. In addition to these, a child affected by mitochondrial encephalomyopathy had heterozygous mutations in NDUFA8 and NDUFS2 genes, while another child with neonatal cardiomyopathy had a complex rearrangement in a single NDUFS7 allele. The latter cases suggest the possibility of unconventional patterns of inheritance in complex I defects.

Molecular analysis of 30 mucopolysaccharidosis type I patients: evaluation of the mutational spectrum in Italian population and identification of 13 novel mutations.

Mucopolysaccharidosis type I (MPS-I orMPS1) is an autosomal recessive condition characterized by a broad range of clinical symptoms. Molecular diagnosis of MPS-I is important for analyzing genotype-phenotype correlation and for selecting patients for innovative therapies. In this study we analyzed 30 Italian MPS-I patients with different phenotypes (20 severe, 6 intermediate, 4 mild) in an attempt to recognize the mutational spectrum in our population and to identify major DNA alterations specific to our country. We identified 93% of mutated alleles (56 out of 60) with the reconstruction of the complete genotype in 26 patients out of 30. Twenty-three different mutations were found, 13 of which are novel while the remaining 10 have been already described. Among the novel mutations we found 5 non conservative missense mutations (A160D, E178K, P183R, G197D, D349Y), one nonsense mutation (C53X), 6 deletions (468-470del3, 486-491del6, 755-759del5, 1251delC, 1839-1867del29, 1902-1903del2), and one splice site mutation (IVS11+5G>A). No common mutation for MPS-I is present in our country. Frequently (40% of the alleles), mutations were found in just one or two patients. However, Q70X, P533R, G51D, and W402X mutations were present in several patients (15%, 13.3%, 13.3%, and 11.6% of the alleles respectively) suggesting a Mediterranean origin of the P533R and G51D mutations. In most cases the patients' genotypes were unique combinations of mutations. The great heterogeneity found in our MPS-I population hampers mutation detection and hinders the genotype-phenotype correlation.

Detection of mutations in the ALD gene (ABCD1) in seven Italian families: description of four novel mutations.

The study describes the mutations causing adrenoleukodystrophy in seven Italian families. Four missense mutations leading to amino acid substitutions, two frameshift mutations leading to a premature termination signal, and a splicing mutation were identified. Mutations 2014C>T (P543L), 2053A>G (Q556A), 673-674insCC, and 1874+1G>A are described for the first time in this report. Mutations 1638C>T (R418W), 1588G>A(R401Q), and 1801-1802delAG are already known to be link to ALD.

Clinical correlations in 16 patients with total or partial laminin alpha2 deficiency characterized using antibodies against 2 fragments of the protein.

BACKGROUND: Many patients with classic congenital muscular dystrophy have been found to have partial or total deficiency of the alpha2 chain of laminin 2 (merosin). This deficiency has mostly been studied using only 1 antibody against a fragment of the protein. OBJECTIVES: To characterize the expression of laminin alpha2 in the skeletal muscle of patients with laminin alpha2 deficiency using antibodies against 2 different portions of the protein and to correlate the immunochemical findings with clinical phenotype. METHODS: We studied 4 patients with total lack of laminin alpha2 and 12 with partial laminin alpha2 deficiency with immunohistochemical techniques and Western blot analysis. We used antibodies recognizing an 80-kd fragment toward the C-terminus and a 300-kd fragment toward the amino-terminal. Patient characteristics examined were functional compromise, magnetic resonance imaging or computed tomography of the brain, electromyography, evoked potentials, and creatine kinase levels. RESULTS: In 4 patients, immunohistochemical analysis revealed no reactivity to either antibody; in 2 patients, the 300-kd fragment alone was partially expressed; in 2 patients, the 80-kd fragment alone was partially expressed; and in 8 patients, both fragments were partially expressed. Immunoblot analysis revealed bands of reduced intensity and normal molecular weight generally corresponding to the immunohistochemical findings. Absence of both fragments or of one with reduction of the other always produced a severe clinical phenotype, while a milder clinical phenotype was observed when both fragments were partially expressed. CONCLUSIONS: Extent of laminin alpha2 deficiency in most cases correlates with clinical phenotype but not with peripheral and central white matter abnormalities. Skin biopsy specimens may reveal laminin alpha2 deficiency in patients who have normal laminin alpha2 levels in muscle biopsy specimens.

CT and MRI in maple syrup urine disease.

We describe a patient with a variant form of maple syrup urine disease who had unusual CT and MRI features that raised the suspicion of a metabolic disease. There were low density and abnormal signal in the white matter and pallida. Sponginess in these areas is the likely explanation for these findings.

Primary carnitine deficiency: heterozygote and intrafamilial phenotypic variation.

Two boys from different families had primary carnitine deficiency: one had cardiomyopathy and myopathy, and the other had hypoglycemia and myopathy but no cardiomyopathy. Uptake of carnitine by cultured fibroblasts was negligible in both patients. Vmax for carnitine transport was reduced to 50% of controls' value in the parents and one brother (who had hypertrophic cardiomyopathy) of the first patient. A brother of the second non-cardiopathic patient died at an early age with autopsy findings of a dilated cardiomyopathy and low cardiac carnitine. Autosomal recessive primary carnitine deficiency can express a variable phenotype in different families as well as within the same family. Heterozygotes can manifest heart involvement.

Fatal ataxic encephalopathy and carnitine acetyltransferase deficiency: a functional defect of pyruvate oxidation?

A 3-year 8-month-old girl died after 14 months of illness characterized by episodes of intermittent ataxia associated with oculomotor palsy, hypotonia, mental confusion, and disturbances of consciousness. In the last 4 months of life, there were signs of liver dysfunction. Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase activities were normal in autopsy brain specimens and in cultured fibroblasts from the patient. Carnitine acetyltransferase was deficient in liver, brain, kidney, and cultured fibroblasts. Medium- and long-chain carnitine acyltransferase activities were normal. It is proposed that a functional defect of acetyl-coenzyme A (acetyl-CoA) utilization in brain mitochondria accompanies the carnitine acetyltransferase deficiency.

Fumarase deficiency is an autosomal recessive encephalopathy affecting both the mitochondrial and the cytosolic enzymes.

A 7-month-old boy died in a demented state after a clinical history characterized by generalized seizures, psychomotor deterioration, and fumaric aciduria. We found a marked deficiency of both mitochondrial and cytosolic fumarases in skeletal muscle, brain, cerebellum, heart, kidney, liver, and cultured fibroblasts. Fumarase activities were 30 to 50% compared with controls in both mitochondria and cytosol from cultured fibroblasts of the parents. Antifumarase cross-reacting material was present in negligible amounts in the patient's tissues. Our data indicate that this disease is an autosomal recessive encephalopathy, due to a single mutation affecting the gene encoding both forms of the enzyme.

Epileptic phenotypes associated with mitochondrial disorders.

OBJECTIVE: To define the clinical and EEG features of the epileptic syndromes occurring in adult and infantile mitochondrial encephalopathies (ME). METHODS: Thirty-one patients with recurrent and apparently unprovoked seizures associated with primary ME were included in the study. Diagnosis of ME was based on the recognition of a morphologic, biochemical, or molecular defect. RESULTS: Epileptic seizures were the first recognized symptom in 53% of the patients. Many adults (43%) and most infants (70%) had nontypical ME phenotypes. Partial seizures, mainly with elementary motor symptoms, and focal or multifocal EEG epileptiform activities characterized the epileptic presentation in 71% of the patients. Generalized myoclonic seizures were an early and consistent symptom only in the five patients with an A8344G mitochondrial DNA point mutation with classic myoclonus epilepsy with ragged red fibers (MERRF) syndrome or "overlapping" characteristics. Photoparoxysmal EEG responses were observed not only in patients with typical MERRF, but also in adult patients with ME with lactic acidosis and strokelike episodes (MELAS), or overlapping phenotypes, and in one child with Leigh syndrome. CONCLUSIONS: Epilepsy is an important sign in the early presentation of ME and may be the most apparent neurologic sign of nontypical ME, often leading to the diagnostic workup. Except for those with an A8344G mitochondrial DNA point mutation, most of our patients had partial seizures or EEG signs indicating a focal origin.

Mild clinical phenotype in a 12-year-old boy with partial merosin deficiency and central and peripheral nervous system abnormalities.

We found partial merosin deficiency in a boy presenting at 12 yr with marked limb weakness and a waddling gait. Magnetic resonance imaging (MRI) showed the characteristic white matter abnormalities of merosin-negative congenital muscular dystrophy. There were also peripheral demyelinating polyneuropathy and evoked potential abnormalities. Unlike classic merosin-negative congenital muscular dystrophy, however, our patient was less hypotonic and weak and was able to achieve independent walking. Both by immunohistochemistry and Western blot merosin was shown to be moderately reduced. By immunostaining the alpha 1 laminin chain was overexpressed and beta 1 laminin chain was reduced. A spectrum of clinical phenotypes is likely to become evident in merosin-deficient patients in relation to the discovery of a range of molecular defects in, and variable expression of, this protein.