White matter dysfunction and its neuropsychological correlates: A longitudinal study of a case of metachromatic leukodystrophy treated with bone marrow transplant

Abstract

A 10-year-old white female who had received a bone marrow transplant (BMT) at 57 months of age as treatment for late infantile onset metachromatic leukodystrophy (MLD), a neurodegenerative autosomal recessive storage disease, showed stabilization of the cognitive degenerative process and demonstrated a partial pattern of cognitive deficits and behavioral abnormalities that has been called NLD (nonverbal learning disabilities) associated with white matter disease. A pattern of good rote memory, reading skills, and concrete language contrasted with poor visual spatial skills, mathematics, and abstract problem solving. She did not show the usual speech prosody and social deficits associated with NLD.     

An Italian Cohort Study Identifies Four New Pathologic Mutations in the ARSA Gene

Metachromatic leukodystrophy is an autosomal recessive neurodegenerative disorder of the myelin metabolism due to the impaired function of the lysosomal enzyme arylsulfatase A. Three major clinical variants of metachromatic leukodystrophy (MLD) have been described: late infantile, juvenile, and late onset. The infantile form, whose clinical onset is usually before the age of 2 years, is the most frequent. The juvenile form manifests itself between 3 and 16 years and the late-onset form manifests at any time after puberty. As of today, more than 150 mutations causing MLD have been identified in the ARSA gene that encodes arylsulfatase A. In this paper, we report our experience with the diagnosis of MLD in seven Italian patients from unrelated families. We found 11 different mutations, four of which have not been previously described: c.1215_1223del9 (p.406_408del), c.601 T>C (p.Tyr201His), c.655 T>A (p.Phe219Ile), and c.87C>A (p.Asp29Glu). Our data show once more that there are still several mutations to be discovered in the ARSA gene and there are rarely repeating ones found in the population. The predictive value of the enzyme activity tests in regard to clinical manifestations is extremely limited.     

Metachromatic Leukodystrophy (MLD): a Pakistani Family with Novel <Emphasis Type="Italic">ARSA</Emphasis> Gene Mutation

A deficiency of the enzyme arylsulfatase A (ARSA) causes a progressive neurodegenerative lysosomal storage disease known as metachromatic leukodystrophy (MLD). Diagnosis is based on the onset of neurological symptoms, presence of gait abnormalities, spasticity, decreased muscle stretch reflexes and neuro-radiological evidence of demyelination. The purpose of the present study was to identify any mutation in the candidate ARSA gene in a family of late infantile MLD patients. The diagnosis of suspected MLD patients was confirmed by a MRI report and low ARSA enzymatic activity in leukocytes. Sanger sequencing of full-length coding regions of ARSA gene was performed. Changes in the nucleotide sequence were determined by comparing the obtained data with the wild-type sequence. mRNA expression was analysed using real-time PCR. A novel base pair substitution at position c.338T>C (p.L113P) of ARSA gene was observed in the family and was confirmed in a normal population via ARMS-PCR and Sanger sequencing. The mRNA expression of ARSA gene showed a significant difference between normal and carrier individuals (p = 0.0008). In silico analysis by POLYPHEN, a pathogenicity prediction tool, predicted the possible damaging nature of this mutation. I-TASSER, a protein-modelling server, demonstrated the effects of this mutation on different domains of the ARSA protein, which plays a crucial role in the structural and functional integrity of enzyme. The novel p.L113P mutation in a Pakistani family with late infantile MLD has a pathogenic and destructive effect on the protein structure and function of ARSA. It is the first case reported in a Pakistani population using genetic analysis.     

Late-onset metachromatic leukodystrophy: molecular pathology in two siblings.

We report on a new allele at the arylsulfatase A (ARSA) locus causing late-onset metachromatic leukodystrophy (MLD). In that allele arginine84, a residue that is highly conserved in the arylsulfatase gene family, is replaced by glutamine. In contrast to alleles that cause early-onset MLD, the arginine84 to glutamine substitution is associated with some residual ARSA activity. A comparison of genotypes, ARSA activities, and clinical data on 4 individuals carrying the allele of 81 patients with MLD examined, further validates the concept that different degrees of residual ARSA activity are the basis of phenotypical variation in MLD.     

Intestinal involvement in metachromatic leukodystrophy

Metachromatic leukodystrophy is a lysosomal storage disease caused by the deficiency of the enzyme arylsulfatase A. If arylsulfatase A is deficient, sulfatide accumulates. Functionally, this accumulation results in progressive neurological deterioration. The reports about the extra nervous system manifestations of metachromatic leukodystrophy are related to the gallbladder involvement such as polyposis. Unexplained vomiting began in a 5½-year-old girl with late infantile metachromatic leukodystrophy. Endoscopy showed multiple polypoid masses in the pylor of the stomach and duodenum. Severe gastrointestinal bleedings occurred during nasogastric feeding. Intestinal intussusception developed later. To the authors' knowledge, intestinal polypoid masses and obstruction with metachromatic leukodystrophy have not previously been reported. The persistent vomiting may be a symptom of intestinal obstruction due to intestinal polypoid masses with metachromatic leukodystrophy. There may be a trend for the development of polypoid masses in intestine as well as in the gallbladder in metachromatic leukodystrophy.     

Juvenile-onset metachromatic leukodystrophy: biochemical and electrophysiologic studies.

A 15-year-old girl with juvenile-onset metachromatic leukodystrophy (MLD) had markedly decreased leukocyte arylsulfatase A activity and low levels of leukocyte beta galactosidase and serum acid phosphatase. There was marked slowing of nerve condition velocity, and metachromasia was seen in biopsied sural nerve. Leukocyte arylsulfatase A activity was decreased in all members of the girl's family, and sural nerve action potentials were abnormal in two asymptomatic siblings. Electrophysiologic studies combined with biochemical studies may aid in the identification of presymptomatic metachromatic leukodystrophy homozygotes or asymptomatic heterozygotes.     

Kindstötung und hebephrenes Syndrom bei metachromatischer Leukodystrophie

We report a patient with metachromatic leukodystrophy (MLD) with a first manifestation of homicide. On admission the patient showed a hebephrenia-like syndrome with inappropriate affect, thought disorder and behavioral changes. Magnetic resonance tomography (MRT) findings suggested a diagnosis of MLD, which was confirmed by a decreased activity of leucocyte arylsulfatase A and an excessive urinary sulfatide excretion.     

Peripheral neuropathy in metachromatic leucodystrophy. A study of 40 cases from south India

BACKGROUND: There is a paucity of literature from India on metachromatic leucodystrophy (MLD), a rare metabolic disorder of childhood resulting from aryl sulfatase A (ASA) deficiency.Patients/ METHODS: Case records of histopathologically verified cases of MLD, evaluated over a period of 12 years at the National Institute of Mental Health and Neurosciences, Bangalore, India, were reviewed. RESULTS: The late infantile group (36) manifested with regression of milestones (all), delayed mile stones (14), gait abnormalities (14), and seizures (11). Despite spasticity (29), there was hypo/areflexia in 25 patients. Optic atrophy (six) was rare. Consanguinity was noted in 25 children and four had a history of similar illness in siblings. Behavioural problems dominated in the juvenile group (four), but associated cognitive decline and hyporeflexia provided a clue to the diagnosis. Low serum ASA (seven of 20), raised cerebrospinal fluid protein (five of 12), and urinary metachromatic granules (two of 32) were infrequent. Electrophysiological evidence of severe demyelinating and length dependent sensory motor neuropathy was observed in all, even in the presence of hyper-reflexia. In addition to metachromatic dysmyelinating neuropathy in all patients, sural nerve biopsy in 20 patients revealed orthochromatic deposits within perivascular macrophages, particularly among those patients with normal ASA values (11 of 14), suggesting the accumulation of other glycosphingolipids. CONCLUSIONS: This study produced some noteworthy observations: the high degree of consanguinity associated with MLD in India, the existence of MLD with normal serum concentrations of ASA, the deposition of orthochromatic lipids, and electrophysiological evidence of a partial conduction block.     

A variant form of metachromatic leukodystrophy without arylsulfatase deficiency

The clinical, pathological, and biochemical findings in a young woman with a new variant of metachromatic leukodystropy (MLD) are reported. The patient showed slow early development and deteriorated further during her first two decades. Nerve conductions were slow, and a sural nerve biopsy showed features of a sulfatide lipidosis. Urinary sulfatide excretion was comparable to that of patients with classic MLD, yet in vitro activity of arylsulfatase A and B and cerebroside sulfatase activity were normal. Skin fibroblasts cultured in medium supplemented with ³H-labeled sulfatide showed accumulation of labeled sulfatide in large amounts, implying a defect in sulfatide hydrolysis in vivo in spite of intact enzyme activity in vitro.     

Pitfalls in the diagnosis of multiple sulfatase deficiency

Multiple sulfatase deficiency (MSD, OMIM 272200) is an autosomal recessive leukodystrophy associated with the deficiency of several, in total seven, sulfatases. The disorder is clinically and biochemically variable. The clinical picture combines features of mucopolysaccharidosis and metachromatic leukodystrophy (MLD, OMIM 250100) in a variable spectrum. Here we report a 3-year old Iranian girl with an MLD-like presentation of MSD. Arylsulfatase A deficiency and sulfatide excretion were found. Differently from what was previously reported in Multiple sulfatase deficiency (MSD, OMIM 272200) is an autosomal recessive leukodystrophy associated with the deficiency of several, in total seven, sulfatases. The disorder is clinically and biochemically variable. The clinical picture combines features of mucopolysaccharidosis and metachromatic leukodystrophy (MLD, OMIM 250100) in a variable spectrum. Here we report a 3-year old Iranian girl with an MLD-like presentation of MSD. Arylsulfatase A deficiency and sulfatide excretion the literature, this girl never showed abnormal mucopolysaccharide excretion in the urine. There were no additional visceral or skeletal signs. She was originally diagnosed as having MLD. Only when she developed ichthyosis were seven additional sulfatases measured. In leukocytes, arylsulfatase A, steroid sulfatase and N-acetylglucosamine-6 sulfatase were profoundly deficient, while iduronate-2 sulfatase and arylsulfatase B were moderately reduced. In fibroblasts, N-acetylglucosamine-6 sulfatase was deficient, while arylsulfatase A was moderately reduced. This case illustrates the possible pitfalls in the clinical and laboratory diagnosis of MSD.     

Adult metachromatic leukodystrophy: disorganized schizophrenia-like symptoms and postpartum depression in 2 sisters

We describe the cases of 2 sisters with adult metachromatic leukodystrophy (MLD). Whereas one sister presented with disorganized schizophrenia-like symptoms as the initial manifestation of MLD, the other remained symptom free except for a 4-week period of postpartum depression. In both patients, there was some residual activity of leukocyte arylsulfatase A (1.7% and 5.5% of normal), and a marked increase in urinary sulfatides was present, as measured by tandem mass spectrometry. An arylsulfatase A pseudodeficiency was therefore excluded. The most common mutations of the adult phenotype, Ile-179-Ser and Pro-426-Leu, were not found. In the literature, only 1 case of adult MLD manifesting as disorganized schizophrenia-like symptoms has been described, whereas postpartum depression has been so far unknown as a presenting symptom of MLD.     

The natural course of gross motor deterioration in metachromatic leukodystrophy

Aim Motor deterioration is a key feature in metachromatic leukodystrophy (MLD). The lack of data about its natural course impedes evaluation of therapeutic interventions. This study aimed to provide data about motor decline in MLD. Method Fifty‐nine patients (27 males, 32 females) with MLD (21 with late‐infantile MLD and 38 with juvenile MLD) were recruited within a nationwide survey (the German LEUKONET). Median (range) age at onset was 17 months (9–27) for the group with late‐infantile MLD and 6 years 2 months (2y 11mo–14y) for the group with juvenile MLD. Gross motor function was assessed using the Gross Motor Function Classification for MLD. Results In late‐infantile MLD, all patients showed loss of all gross motor function until 3 years 4 months of age. Patients with juvenile MLD showed a more variable and significantly longer motor decline (p<0.001). For a patient with the juvenile form showing first gait disturbances, the probability of remaining stable for more than 1 year was 84%, and 51% for more than 2 years. Having lost independent walking, subsequent motor decline was as steep as in the late‐infantile form (median 5mo, interquartile range 3–22). Interpretation The course of motor disease was more variable in juvenile MLD with respect to onset and dynamics. However, the motor decline after the loss of independent walking was similarly steep in both forms. These data can serve as a reference for clinical studies that are topics of current research and allow definition of inclusion/exclusion criteria.     

Atypical clinical course in juvenile metachromatic leukodystrophy involving novel arylsulfatase A gene mutations

A male and female with juvenile metachromatic leukodystrophy (MLD) with unusual manifestations are presented, each involving a novel arylsulfatase A gene mutation. One patient demonstrated acute intermittent encephalopathic episodes for 1 year after having received the diagnosis of MLD at the age of 6 years. The other patient presented at the age of 5 years with acute hemiparesis, which was diagnosed as acute disseminated encephalomyelitis and resolved in 3 weeks. After 2 years of remission he started to show progressive neurological deterioration. The episodic manifestations in both patients were associated with acute, resolving cerebral lesions on magnetic resonance imaging accompanying or preceding the classical demyelinating lesions of MLD. The diagnosis of MLD was based on arylsulfatase A enzyme activity levels and genetic analysis, and after the exclusion of neurological conditions such as encephalitis, vasculopathy, or mitochondrial disorders. The pathogenesis of this previously undescribed finding in MLD is unknown but might be related to a susceptibility of myelin to acute damage.     

Novel mutations in the arylsulfatase A gene in eight Italian families with metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disease caused by arylsulfatase A (ARSA) deficiency. We analysed the ARSA gene in eight unrelated Italian families with different clinical variants of MLD and identified three novel mutations: two Ser406Gly, (Glu329Ter) associated with late infantile MLD and one (Leu52Pro) with juvenile MLD. Only one family carried a pseudodeficiency allele (Asn350Ser). The IVS2+1G>A mutation occurred in four families. We also identified three polymorphisms, all in heterozygosis: Thr391Ser was present in five families, Trp193Cys in four families, and Ala210Ala in one family. We could identify 100% of the alleles causing MLD in the families, involving 12 different mutations, resulting in improved prognosis and genetic counselling.     

Specific downregulation and mistargeting of the lipid raft-associated protein MAL in a glycolipid storage disorder

Metachromatic leukodystrophy (MLD) is a lysosomal lipid storage disease caused by arylsulfatase A deficiency. In MLD patients the sphingolipid sulfatide increasingly accumulates leading to progressive demyelination. We have analysed arylsulfatase A-deficient mice, a MLD mouse model, and we show that accumulation of sulfatide is not restricted to the lysosomal compartment but also occurs in myelin itself. Although, this sulfatide storage did not affect the overall composition of most myelin proteins, it specifically caused a severe reduction of MAL. This demonstrates a regulatory link between sulfatide accumulation and MAL expression and indicates the existence of regulatory mechanisms between lipid and myelin protein synthesis in oligodendrocytes. In addition, in cultured renal epithelial cells, sulfatide accumulation diverts MAL to the late endosomal/lysosomal compartment and thus also affects the intracellular distribution of MAL. The specific reduction and mistargeting of MAL protein as a reaction to sulfatide overload may contribute to the pathogenic mechanisms in metachromatic leukodystrophy.     

Adult metachromatic leukodystrophy. Value of computed tomographic scanning and magnetic resonance imaging of the brain

Patients with adult-onset metachromatic leukodystrophy (MLD) often present with personality changes or deterioration of cognitive functions. Although rare, this form of MLD should be included in the differential diagnosis of psychotic and dementing disorders. The following case report describes a 38-year-old man with adult-onset MLD, who carried the diagnosis of schizophrenia and was treated as a schizophrenic for a number of years. Metachromatic leukodystrophy was initially suspected because of white matter abnormalities detected on computed tomographic scans and magnetic resonance images of the brain. The diagnosis of MLD was confirmed by the discovery of markedly reduced leukocyte arylsulfatase A activity. The computed tomographic and magnetic resonance imaging findings in MLD are reviewed.     

Multiple molecular forms of arylsulfatase A in different forms of metachromatic leukodystrophy (MLD).

Arylsulfatase A (ARA) can be separated into six to eight individual enzymatic bands of activity by isoelectric focusing on cellulose acetate membranes. The residual ARA activity in juvenile metachromatic leukodystrophy (MLD) has a single band of activity with apI of 5.5, whereas the residual ARA in the late infantile form of MLD has three bands of activity with pI range of from 5.4 to 5.8. The technique of isoelectric focusing on cellulose acetate membranes demonstrates enzymatic differences which can be correlated with the clinical form of the disease.     

Isolated peripheral neuropathy in atypical metachromatic leukodystrophy: a recurrent mutation

BACKGROUND: Metachromatic leukodystrophy (MLD) is a genetic neurodegenerative disorder resulting from a deficiency of arylsulfatase A. Late onset forms are relatively rare. Central nervous system (CNS) involvement is characteristic at all ages. METHODS: A patient in her late 40s with peripheral neuropathy was assessed by EEG, evoked potentials, CT and nerve conduction studies. Nerve and muscle biopsy samples were investigated by electron microscopy. Arylsulfatase A activity in leukocytes and excreted cerebroside sulfate were determined. The arylsulfatase A gene was investigated for mutations using polymerase chain reaction (PCR) and DNA sequencing. The identified mutation was expressed transiently in African green monkey kidney (COS) cells to determine the effect of the mutation on arylsulfatase A activity. RESULTS: Central nervous system functions were normal. Nerve conduction velocities were decreased. Sural nerve biopsy showed inclusions typical of MLD. Arylsulfatase A was less than 5% of normal. A homozygous mutation thr286pro was identified in the arylsulfatase A gene and demonstrated to be deleterious through transient expression studies. CONCLUSIONS: Our patient has a progressive peripheral neuropathy but has apparently intact CNS function at her present age of 57 years. Biochemical, physiological and pathological findings are consistent with a diagnosis of MLD. A homozygous mutation, thr286pro, found in her arylsulfatase A gene, decreased enzyme activity to a level consistent with a late onset form of MLD.     

Sweat gland pathology in neurodegenerative disorders]

Ultrastructural pathology on sweat gland epithelium was studied in various neurodegenerative disorders; neuronal ceroid-lipofuscinosis (NCL), Lafora disease, mucopolysaccharidosis, GM1 gangliosidosis, Nieman-Pick disease, Fabry disease, Krabbe disease and metachromatic leukodystrophy (MLD). Every disease had its own characteristic inclusions in sweat gland epithelium. Curvilinear profiles and fingerprint patterns were seen in NCL, but there were no morphological differences among late infantile, early juvenile and juvenile types. On the other hand, the granular matrix was characteristic of the infantile type. The presence of specific inclusions in a 23-year-old female carrier with Fabry disease indicated that a skin biopsy was one of the useful methods to detect a female carrier. In MLD and Krabbe disease, there were disease specific inclusions in sweat gland epithelium. These results indicate that the sweat glands should be investigated when a skin biopsy is performed for the diagnosis of neurodegenerative diseases.