Cerebroside-sulphatase and arylsulphatase A deficiency in metachromatic leukodystrophy (ML)

Properties, metabolism and roles of sulfogalactosylglycerolipid in male reproduction

Sulfogalactosylglycerolipid (SGG, aka seminolipid) is selectively synthesized in high amounts in mammalian testicular germ cells (TGCs). SGG is an ordered lipid and directly involved in cell adhesion. SGG is indispensable for spermatogenesis, a process that greatly depends on interaction between Sertoli cells and TGCs. Spermatogenesis is disrupted in mice null for Cgt and Cst, encoding two enzymes essential for SGG biosynthesis. Sperm surface SGG also plays roles in fertilization. All of these results indicate the significance of SGG in male reproduction. SGG homeostasis is also important in male fertility. Approximately 50% of TGCs become apoptotic and phagocytosed by Sertoli cells. SGG in apoptotic remnants needs to be degraded by Sertoli lysosomal enzymes to the lipid backbone. Failure in this event leads to a lysosomal storage disorder and sub-functionality of Sertoli cells, including their support for TGC development, and consequently subfertility. Significantly, both biosynthesis and degradation pathways of the galactosylsulfate head group of SGG are the same as those of sulfogalactosylceramide (SGC), a structurally related sulfoglycolipid important for brain functions. If subfertility in males with gene mutations in SGG/SGC metabolism pathways manifests prior to neurological disorder, sperm SGG levels might be used as a reporting/predicting index of the neurological status.

Sulfatase activities towards the regulation of cell metabolism and signaling in mammals

In higher vertebrates, sulfatases belong to a conserved family of enzymes that are involved in the regulation of cell metabolism and in developmental cell signaling. They cleave the sulfate from sulfate esters contained in hormones, proteins, and complex macromolecules. A highly conserved cysteine in their active site is post-translationally converted into formylglycine by the formylglycine-generating enzyme encoded by SUMF1 (sulfatase modifying factor 1). This post-translational modification activates all sulfatases. Sulfatases are extensively glycosylated proteins and some of them follow trafficking pathways through cells, being secreted and taken up by distant cells. Many proteoglycans, glycoproteins, and glycolipids contain sulfated carbohydrates, which are sulfatase substrates. Indeed, sulfatases operate as decoding factors for a large amount of biological information contained in the structures of the sulfated sugar chains that are covalently linked to proteins and lipids. Modifications to these sulfate groups have pivotal roles in modulating specific signaling pathways and cell metabolism in mammals.

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.

Sulfatases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility

Sulfatases, which cleave sulfate esters in biological systems, play a key role in regulating the sulfation states that determine the function of many physiological molecules. Sulfatase substrates range from small cytosolic steroids, such as estrogen sulfate, to complex cell-surface carbohydrates, such as the glycosaminoglycans. The transformation of these molecules has been linked with important cellular functions, including hormone regulation, cellular degradation, and modulation of signaling pathways. Sulfatases have also been implicated in the onset of various pathophysiological conditions, including hormone-dependent cancers, lysosomal storage disorders, developmental abnormalities, and bacterial pathogenesis. These findings have increased interest in sulfatases and in targeting them for therapeutic endeavors. Although numerous sulfatases have been identified, the wide scope of their biological activity is only beginning to emerge. Herein, accounts of the diversity and growing biological relevance of sulfatases are provided along with an overview of the current understanding of sulfatase structure, mechanism, and inhibition.

Complications in the genotypic molecular diagnosis of pseudo arylsulfatase A deficiency

Metachromatic leukodystrophy (MLD) is a severe neurodegenerative disease associated with deficient arylsulfatase A activity. Biochemical confirmation of this disorder has been complicated by a clinically normal but enzymatically deficient variant, pseudo arylsulfatase-A deficiency (PD). The PD mutation is associated with two A-->G transitions in the arylsulfatase A gene. They can be detected simultaneously with a recently developed 3'-mismatch polymerase chain reaction, hence providing a rapid method for genotypic identification and resolving ambiguities of carrier identification based solely on enzyme analyses. However, we now report further genotypic complexities in the molecular diagnosis of PD due to the occurrence of another variant in which only one of the two A-->G mutations of the PD allele was present. This variant confers reduced but readily detectable enzyme activity and behaves as a silent allele in the 3'-mismatch polymerase chain reaction, thus leading to conflicting and erroneous genotype assignments in a family in which both variants and MLD co-exist. The inconsistency was resolved after pedigree validation and further molecular analyses in which the two A-->G mutations were assayed separately with allele-specific oligonucleotides. Because arylsulfatase A analysis is one of the most commonly requested lysosomal enzyme assays and the PD mutant allele frequency is high in the general population, complexities as described in this family may be a recurrent problem that can be solved only with combined enzymatic and detailed molecular analyses.

Diagnosis of arylsulfatase A deficiency

Metachromatic leukodystrophy (MLD) is a neurologically devastating autosomal recessive disorder in humans associated with deficient arylsulfatase A activity. However, clinically normal individuals described as being pseudo-arylsulfatase-A deficient also demonstrate the same deficiency. Genotypically, they may be homozygous for the pseudodeficiency mutation (associated with 2 A-->G transitions in the cDNA of arylsulfatase A) or heterozygous with one pseudodeficiency and one MLD allele. Using as examples 2 families in which the pseudo deficiency condition occurs either independently or together with MLD, we demonstrate the utility of a proposed diagnostic protocol to provide complete genotype identification of individuals suffering from arylsulfatase A deficiency. Patient fibroblasts are extracted for DNA and a cytoplasmic fraction, which is used for arylsulfatase A enzyme assay. This will identify an arylsulfatase A-deficient group, which is further analyzed electrophoretically. Cells from the clinically affected patients with MLD are completely deficient in arylsulfatase A activity, whereas those from the pseudodeficient individuals demonstrate a characteristic residual arylsulfatase A activity detectable only after electrophoresis. Within this pseudodeficient group, gene amplification of DNA specific for the A-->G mutations will distinguish between those who are homozygous for the pseudodeficiency allele and those who are compound heterozygous for the pseudodeficiency and MLD alleles. This protocol of complete genotype identification requires only about 10(6) fibroblasts (1 x 100 mm dish) and 2 days to complete. Such variant-specific genotype identification increases accuracy and prognostic value of the diagnosis. It will likely become the preferred choice for diagnosis of genetic disease in the future as more variant-specific mutations are identified at the molecular level.

Structure and evolution of the human prosaposin chromosomal gene

The gene for prosaposin was characterized by sequence analysis of chromosomal DNA to gain insight into the evolution of this locus that encodes four highly conserved sphingolipid activator proteins or saposins. The 13 exons ranged in size from 57 to 1200 bp, while the introns were from 91 to 3812 bp in length. The regions encoding saposins A, B, and D each had three exons, while that for saposin C had only two. This sequence included the regions that encode the carboxy terminus of the signal peptide, the four mature prosaposin proteins, and the 3' untranslated region. Primer extension studies indicated that over 99% of the coding sequence was contained in these 19,985 bp. Use of PCR and reverse PCR techniques indicated that the most 5' coding approximately 140 bp contained large introns and at least two small exons. Analyses of the intronic positions in the saposin regions indicated that this gene evolved from an ancestral gene by two duplication events and at least one gene rearrangement involving a double crossover after introns had been inserted into the gene.

Cellular localization of soluble and membrane-bound forms of arylsulfatase in rat brain

The cellular localization of the soluble and membrane-bound forms of the enzyme, arylsulfatase (ArS), in rat brain was investigated by measuring their activities in rat striatum after unilateral lesioning with the neurotoxin, kainic acid. Membrane-bound ArS (C form of ArS) activity was found to increase after lesioning and the increase paralleled that of the astroglial marker enzyme, glutamine synthetase. Total soluble ArS (A and B forms of ArS) was shown to decrease on day 2 after the kainic acid injection but rapidly increase thereafter. When the two soluble forms of arylsulfatase were measured separately, the activity associated with the A form was found to initially decrease followed by a rapid increase in activity, whereas the activity of the B form of the enzyme increased over the entire duration of the experiment. These data suggest that the ArS-C and B form of arylsulfatase predominate in proliferating astroglial cells, whereas the A form of arylsulfatase is present both in neuronal cell bodies and astroglia associated with the rat striatum.

Human chromosome 22

The acrocentric chromosome 22, one of the shortest human chromosomes, carries about 52 000 kb of DNA. The short arm is made up essentially of heterochromatin and, as in other acrocentric chromosomes, it contains ribosomal RNA genes. Ten identified genes have been assigned to the long arm, of which four have already been cloned and documented (the cluster of lambda immunoglobulin genes, myoglobin, the proto-oncogene c-sis, bcr). In addition, about 10 anonymous DNA segments have been cloned from chromosome 22 specific DNA libraries. About a dozen diseases, including at least four different malignancies, are related to an inherited or acquired pathology of chromosome 22. They have been characterised at the phenotypic or chromosome level or both. In chronic myelogenous leukaemia, with the Ph1 chromosome, and Burkitt's lymphoma, with the t(8;22) variant translocation, the molecular pathology is being studied at the DNA level, bridging for the first time the gap between cytogenetics and molecular genetics.

Lipids of nervous tissue: composition and metabolism

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Arylsulfatase in natural killer cells: its possible role in cytotoxicity

Ultrastructural cytochemistry of natural killer cells enriched by Percoll gradient centrifugation showed them to possess arylsulfatase (aryl-sulfate sulfohydrolase, EC 3.1.6.1). The enzyme was located in vesicles, granules, and the parallel tubular arrays, organelles characteristic for cytotoxic lymphocytes. Biochemically, peak enzyme activity correlated with the Percoll fractions containing cells with cytotoxicity for melanoma target cells. Treatment of natural killer cells with Na2SO4, a competitive inhibitor of arylsulfatase, suppressed cytotoxicity by almost 50%. Electron microscopy of effector-target cell conjugates, which had been permitted to incubate for only 30 min, disclosed numerous arylsulfatase-positive sites at the points of contact between the effector/target cell membranes. Thus, the enzyme was translocated to the surface before lysis of the target cell was morphologically evident. It is postulated that the parallel tubular arrays play a role in this translocation and that arylsulfatase may function in the degradation of cerebroside sulfate ester components of the target cell membrane to initiate the lytic event.

Soluble arylsulphatases in the rabbit salivary glands. A light and electron microscopy study

A histochemical study was effected, by light and electron microscopy, on the activity of arylsulphatases A and B in the submandibular and sublingual glands of male and female rabbits, distinguishing, among the latter, between the physiological estrus and anestrus condition. The results obtained demonstrated that the enzymatic activity is more intense in the sublingual gland and that the estrus condition causes an increase in this activity. No correlation was found between the topochemical distribution of the soluble arylsulphatases and that of sulphates.

Somatic cell hybridization studies on the genetic regulation and allelic mutations in metachromatic leukodystrophy

Metachromatic leukodystrophy is a hereditary neurodegenerative disease associated with deficient arylsulfatase A activity. Clinical variants differ in onset times and severity of the disease but each breeds true within families. Somatic cell hybridization techniques were used to clarify the genetic relationship among these mutants. Hybrid clones isolated with a nonselective method from fusing fibroblasts of an infantile and a juvenile variant did not show complementation of arylsulfatase A activity. Hence, these clinical variants are allelic mutants. Previous somatic cell hybridization studies suggested that "arylsulfatase A-deficiency" is a dominant phenotype, in contrast to its apparent recessive mode of inheritance. To resolve this discrepancy, hybrid clones from fusing normal and arylsulfatase A-deficient fibroblasts were isolated nonselectively. They continued to express arylsulfatase A activity. Hence, even in vitro, "arylsulfatase A-deficiency" remains as a recessive phenotype.

Ascorbic acid sulfate sulfohydrolase (C2 sulfatase): the modulator of cellular levels of L-ascorbic acid in rainbow trout

The enzyme L-ascorbic acid 2-sulfate sulfohydrolase (C2 sulfatase) was purified from rainbow trout liver. The enzyme catalyzes the hydrolysis of L-ascorbic acid 2-sulfate and has a pH optimum at 6.0. It has a molecular weight of about 117,500 at pH 5.0 and is inhibited by a number of sulfhydryl blocking agents including L-ascorbic acid. C2 sulfatase activity was observed in most metabolic organs of rainbow trout. These findings suggest that the physiologic role of the enzyme is to maintain adequate cellular concentrations of L-ascorbic acid in the fish. The activity of the enzyme is controlled by L-ascorbic acid through feedback inhibition. Comparison of kinetic constants and inhibition patterns suggests that C2 sulfatase is structurally identical to human arylsulfatase A. However, unlike C2 sulfatase, human arylsulfatase A may not be involved in ascorbate metabolism. Its physiologic substrate is reported to be cerebroside-3-sulfate, not L-ascorbic acid 2-sulfate. A scheme is proposed to account for the functional divergence of these two structurally identical enzymes.

Metachromatic leucodystrophy: review of 38 cases

Clinical and laboratory features of 38 children suffering from metachromatic leucodystrophy (MLD) are reported. Twenty-four children with the late infantile form of MLD presented between ages 6 and 25 (mean 17) months with a delay or deterioration in walking, followed by a general loss of abilities. There was severe handicap by age 3 years and death occurred between 5 months and 8 years after presentation. Neurological signs at the time of diagnosis were varied. Motor nerve conduction velocity was slowed in the 18 children tested. The disease became evident at a later age in 14 children. One boy presented at 13 years, while in the remainder there appeared to be two clinical patterns of the disease which could be termed (1) early juvenile or intermediate and (2) juvenile MLD. In 7 children with early juvenile or intermediate MLD a gait disorder developed between ages 4 and 6 (mean 5) years. This was accompanied in 4 children, and followed between 8 and 26 months later in the remaining 3, by loss of other abilities. Neurological signs were varied. Motor nerve conduction velocity was slowed in 2 of the 5 patients tested. Six children with juvenile MLD presented between ages 6 and 10 years with educational or behavioural difficulties. Motor disorders arose from 6 months to 4 years later. Neurological signs at the time of diagnosis, although mixed, were predominantly extrapyramidal and motor nerve conduction velocity was slowed in 2 of the 3 children tested. In the early juvenile form of MLD, progression of the disease was slower than in the late infantile form and death occurred between 31/2 and 18 years after presentation. Only one-third of patients had fits and these tended to be a late feature.

Leukocyte sulfatidase for the reliable diagnosis of metachromatic leukodystrophy

A simple assay technique for the determination of sulfatidase activity in leukocytes has been developed for the reliable diagnosis of metachromatic leukodystrophy (MLD). Sulfatide is tritiated in sphingosine and fatty acid by reduction with [3H]sodium borohydride in alkali in the presence of palladium chloride. This labeled natural substrate for aryl sulfatase A (AsA) is hydrolyzed by normal human leukocytes in 25 mM-acetate buffer, pH 5.0, in the presence of 0.3% sodium taurodeoxycholate. The enzyme activity is greatly improved after dialysis, exhibiting better linearity with protein concentration. It is stimulated maximally by 5 mM-MnCl2 with an apparent Km of 0.17 mM for the substrate. Patients with MLD exhibited virtually no detectable sulfatidase activity although they had residual AsA activity that was measured with the synthetic substrate, p-nitrocatechol sulfate (NCS). Potential heterozygotes could be identified by the sulfatidase assay in instances where the NCS assay for AsA was inconclusive. Several individuals with levels of AsA activity characteristic of MLD, including a few healthy carriers and certain patients with unknown neurological diseases, were shown not to have MLD by the presence of measurable levels of sulfatidase in their leukocytes.

[Metachromatic leukodystrophy. Report of a case]

A case of metachromatic leucodystrophy in a three years old female patient is reported. Histopathological examination revealed metachromatic inclusions within the cytoplasms of the neurons, which led the authors to comment on the physiopathogenesis of this disease, grouping it in category of the lipidoses.

[Metachromatic leukodystrophy: report of 2 cases with histochemistry of nerves and muscles]

Two cases of metachromatic leukodystrophy, of the late infantile form are reported. The patients were a girl and a boy of 2 years 10 months old, with initial normal development, but by the age of 18 months began with gait disturbances, difficulty to speak and developed progressive mental deterioration, with signs of long tract involvement, absence of deep tendon reflexes, spasticity, blindness, muscle atrophy and finished in a vegetative state. The diagnosis was made electromyography (signs of denervation), motor nerve conduction velocity (very decreased), assay of arylsulfatase A in the urine (absence of activity), sural nerve biopsy (demyelination and presence of metachromatic granules by the cresyl-violet and toluidine blue) and muscle biopsy (atrophy of type I fibers and presence of metachromatic material in the intramuscular nerve fibers). A quick revision about diagnostic methods, transmission, pathogenesis and variant forms is made.

Adult metachromatic leucodystrophy: clinicopathological report of two familial cases with slow course

Two cases of adult metachromatic leucodystrophy in one family are reported. The main clinical features in both were predominantly psychiatric with alcoholism and an extremely long duration of the illness. Neuropathological examination revealed a similar distribution of the lesions in both, and scanty metachromatic accumulation in the CNS and not at all elsewhere. The great variability of the lengths of the courses is stressed. The duration in no way seems to be linked to the age of onset, except in the typical infantile form. The authors argue that different lengths of history correlate with distinct neuropathological findings, and may possibly be related to qualitative differences in the involved enzyme disturbance. Therefore, the authors suggest that the classification based on the age of onset be enlarged with a further one distinguishing between 'rapid' and 'slow' course types.

Basic findings and current developments in sphingolipidoses

Sphingolipidoses are caused by recessively inherited deficiencies of lysosomal hydrolases. The clinical backgrounds of and current biochemical and genetic approaches to the different forms and variants of gangliosidoses, trihexosylceramidosis (Fabry's disease), galactosylceramidosis (Krabbe's disease), sulfatidoses (metachromatic leukodystrophies), glucosylceramidosis (Gaucher's disease), sphingomyelinoses (Niemann-Pick disease) and ceramidosis (Farber's disease) are presented.

Clinical and ultrastructural ocular histopathologic studies of adult-onset metachromatic leukodystrophy

A twin brother and sister with adult-onset metachromatic leukodystrophy developed progressive central acuity loss and optic disk pallor. Both had normal electroretinograms and fluorescein angiography. Postmortem examination of the sister's eyes by histochemistry and electron microscopy revealed ganglion cell loss and optic atrophy. Cerebroside sulfate had accumulated in optic nerve glial cells. Optic atrophy was more advanced than in previously reported cases of infantile-onset metachromatic leukodystrophy. The pathologic process seemed to be retrograde optic nerve degeneration due to abnormal myelin metabolism.

The cerebral lipidoses

The disorders presented consist of those clinical entities in which a reasonably well defined lipid storage material accumulated within nervous tissue. Many other progressive, degenerative disorders are suspected of being storage disorders, but their chemical pathology remains unclear. Collectively this group could be designated the sphingolipidoses. In each case, the disease is a genetic disturbance and transmitted as an autosomal recessive. Sphingolipid storage in each disorder is associated with deficient activity of a specific degradative enzyme or enzyme system, and these deficient enzymes are all lysosomal hydrolases. Lysosomal hydrolases catalyze the breakdown of complex molecules in digestive vacuoles (phagocytic or autophagic) within the cells. Lysosomes show structural latency (requiring osmotic shock or freeze thawing in vitro); their enzymes show maximal activity at acidic pH ranges, and on electron microscopic examination they appear as small, electron-dense intracellular bodies. These hydrolytic enzymes seem to have some form of biological vulnerability in terms of their genetic expression, and this vulnerability underlies the sphingolipidoses. Diagnosis in each case is primarily a clinical problem. The presentation of these disorders, especially in intermediate or advanced forms, is sufficiently distinctive to permit a reasonably accurate diagnosis on the basis of history, physical examination, and routine laboratory data. Patients seen in early stages may be more difficult to recognize but follow-up evaluations usually clarify the problem. Specific enzyme assays are now available for confirmation of the diagnosis in these disorders. A frequent finding in this connection is an increase in the activities of noninvolved lysosomal hydrolases in the storage disorders. Once a case is clinically diagnosed, the clinician has the responsibility of ensuring that proper genetic counseling is made available to the affected families. Considerable supportive care is needed in each case. These patients can survive for prolonged periods, and great stress is placed on their families by these prolonged, hopeless illnesses. Since the disorders affect infants or young children, their parents are usually young adults in their early reproductive years. It is essential that they receive information concerning the risk of subsequent pregnancies. Specific diagnosis of the fetus in early pregnancy can be made now by amniocentesis and enzyme assays on cultured fibroblasts. If the fetus is a homozygote on the basis of enzyme assays, the option of therapeutic abortion should be discussed with the family. For many parents there will be considerable sensitivity to the ethical implications of this course and, if any doubt arises, ethical or pastoral consultation should be sought. Although there are no specific therapeutic approaches, a considerable degree of supportive care can and should be given. In the gangliosidoses and late in the course of the leukodystrophies, seizures will present management problems...

[Sphingolipid storage disease as an example of a molecular neuropathology (author's transl)]

A short survey on the sphingolipid storage diseases is presented. The chemical nature of the accumulated substances is related to the genetically induced enzymic blocks on their biodegradation. Two disorders are stressed with alter the nervous system: metachromatic leukodystrophy and familiar infantile amaurotic idiocy (GM2-gangliosidosis). The difficulties in the causal interpretation of three variants of the latter disease due to the involvement of isoenzymes are dealt with. The relationship between the enzyme defect in these disorders and their time of clinical onset is discussed. Finally, the diagnostic possibilities are presented which are a prerequisite for preventing a further dissemination of these therapy-resistent inborn errors of metabolism.

Cerebroside sulfatase activity in cultivated human skin fibroblasts and amniotic fluid cells;

In an effort to improve the precision in prenatal monitoring for metachromatic leukodystrophy, levels of cerebroside sulfatase were determined in fibroblasts and amniotic fluid cells. Cells from MLD patients demonstrated no significant sulfatide hydrolysis, whereas cultures from heterozygous subjects hydrolyzed diminished but definite amounts of sulfatide. Cells from a fetus with low arylsulfatase A activity were able to cleave considerable amounts of sulfatide; enzyme assays performed postnatally suggest that the infant is heterozygous for MLD. This report documents the value of cerebroside sulfatase assays in the in utero monitoring for MLD.

A preclinical case of late adult metachromatic leukodystrophy? Manifestation only with lipid abnormalities in urine, enzyme deficiency and decrease of nerve conduction velocity

In a clinically unremarkable 39 year old sister of a patient afflicted with late adult metachromatic leukodystrophy, metachromatic deposits in the epithelial cells of the urine sediment, a high sulphatide excretion in the urine, and a deficiency of arylsulphatase A in urine and leucocytes were found. The motor nerve conduction velocity of the peripheral nerves in upper and lower extremities was distinctly decreased. Cerebral disturbances were not evident. It is surmised that this patient is a case of late adult metachromatic leukodystrophy in an early stage of the disease without obvious clinical signs. The peripheral neuropathy found by neurophysiological examination is interpreted as an early symptom of the disease.