Neurofilaments and NFL-TBS.40-63 peptide penetrate oligodendrocytes through clathrin-dependent endocytosis to promote their growth and survival in vitro.

Neurofilaments (NF) are released into the cerebrospinal fluid (CSF) during multiple sclerosis (MS), but their role outside the axon is still unknown. In vitro NF fractions, as well as tubulin (TUB), increase oligodendrocyte (OL) progenitor proliferation and/or their differentiation depending on the stage of their purification (Fressinaud et al., 2012). However the mechanism by which NF enter these cells, as well as that of synthetic peptides displaying NFL-tubulin-binding site (NFL-TBS.40-63) (Fressinaud and Eyer, 2014), remains elusive. Using rat OL secondary cultures we localized NF, TUB, and NFL-TBS.40-63 by double immunocytochemistry and confocal microscopy. After treating OL cultures with NF P2 (2nd pellet of the purification), or TRITC-TUB, these proteins were localized in the cytoplasmic processes of myelin basic protein (MBP+) expressing OL. Similarly biotinylated NFL-TBS.40-63 synthetic peptides and KER-TBS.1-24 were detected in OL progenitors, differentiated (CNP+) and MBP+ OL. In addition, NFL-TBS.40-63 colocalized with cholera toxin, a known marker of endocytosis, within the cells. Pretreatment of OL by methyl ß cyclodextrin abolishes both cholera toxin and NFL-TBS.40-63 uptake, indicating endocytosis. Clathrin-dependent endocytosis was further confirmed by treatment with dynasore, a dynamin inhibitor, which inhibited the uptake of peptides, as well as NFP2 fractions, by 50%. This study demonstrates that axon cytoskeletal proteins and peptides can be internalized by OL through endocytosis. This process could be involved during demyelination, and the release of axon proteins might promote remyelination.

[Oligodendroglial defect and insufficiency of remyelination during MS: anatomoclinical and experimental comparative study]. / Déficit oligodendrocytaire et insuffisance de la remyélinisation au cours de la SEP: étude anatomoclinique et expérimentale comparative.

INTRODUCTION: The mechanisms responsible for the failure of remyelination during MS are poorly understood. We have analyzed in which way oligodendrocytes (OL) could be involved. METHODS: The number of remyelinated fiber per OL has been determined in 18 chronic MS lesions and compared to normal appearing white matter (NAWM), as well as in the center of lysophosphatidyl choline (LPC)-induced lesions in adult rats in which remyelination was accelerated by microinjection of neurotrophin-3 (NT-3). RESULTS: In chronic MS lesions and in LPC-induced lesions the number of myelinated fibers per OL was strongly decreased compared to NAWM and to animals treated with NT-3 respectively. CONCLUSION: Our results suggest that the capacity of OL to remyelinate axons could be impaired, due to successive relapses, during MS.

[Lesion mechanism dependent, differential changes in neurofilaments and microtubules: a pathological and experimental study]. / Modifications des neurofilaments et des microtubules axonaux en fonction du mécanisme lésionnel: étude pathologique et expérimentale.

INTRODUCTION: The consequences of axonal or demyelinating injuries on the axonal cytoskeleton have rarely been described. METHODS: We have compared the density of fibers labeled by anti-neurofilaments (NF) and -beta tubulin (TUB) to the density of total fibers in nine patients with axonal neuropathies of undetermined etiology (AUE), six with necrotizing angeitis with neuropathy (NAN), seven with chronic inflammatory demyelinating neuropathy (CIDP) and in five controls, as well as in six patients with chronic multiple sclerosis (MS). We also studied demyelinated rat corpus callosum after lysophosphatidyl (LPC) microinjection. RESULTS: In AUE and NAN NF positive fibers decreased together with total fiber density, whereas TUB increased. In demyelinating lesions TUB was not altered (CIDP) or strongly decreased (MS, LPC); NF were strongly reduced in MS (where axon loss was prominent) and in LPC lesions (despite the lack of fiber degeneration) and for fiber densities<3900/mm2 in CIDP. CONCLUSION: The initial mechanism of a disease, either axonal degeneration or demyelination, could result into a specific pattern of axonal cytoskeleton alterations.

[Necrotizing vasculitis of the peripheral nervous system: comparison of the axon cytoskeleton abnormalities with other types of neuropathies]. / Vasculites nécrosantes du système nerveux périphérique: comparaison des anomalies du cytosquelette axonal avec d'autres types de neuropathies.

Morphometric and immunocytochemical data obtained from nerve biopsies in six patients with necrotizing angiopathic neuropathy were compared with the data obtained in five control patients without neurologic disease. The density of myelinated fibers were greatly decreased in all patients (more than 55 p.cent), and reached 70 p.cent in four patients. The g myelination ratio was elevated in one patient, indicating demyelination. The number of fibers immunolabeled for the neurofilament (NF) light chain (L) was also decreased from 31 to 96 p.cent. Labeling for medium (M) and heavy (H) NF subunits was less affected. On the contrary, the number of fibers expressing beta-tubulin (TUB) increased by 38 to 141 p.cent and the ratio of the number of fibers expressing TUB and NFL (TUB/NFL) was increased 3 to 33-fold (p<0.05). We have previously reported similar, though less pronounced, anomalies in axonopathies of unknown cause. These results suggest that diverse etiologies may lead to the same type of lesions of the axon cytoskeleton.

[Chronic inflammatory polyradiculoneuritis and the axonal cytoskeleton: morphometric and immunocytochemical data]. / Polyradiculonévrites inflammatoires chroniques et cytosquelette axonal: données morphométriques et immunocytochimiques.

We report morphometric and immunocytochemical data obtained from nervous biopsy in 7 patients with chronic inflammatory demyelinating neuropathy (CIDP), compared to 5 controls (without neurological involvement). Fiber loss was present in all cases and reached 50 p. 100 or more in 4 cases. The g myelination ratio was elevated in 3 cases only, indicating demyelination. The number of fibers labelled for the L subunit of neurofilaments was normal in cases with moderate fiber loss and dropped down for densities < 3900/mm2 (4 cases). Labelling with anti-GAP43 antibody was considerably increased in 3 cases, but did not correlate with fiber density or disease duration. These data confirm the importance of axonal lesions in CIDP and offer the opportunity to discuss their pathophysiological mechanisms.

[Isolated angiitis of the central nervous system. Report of two cases and review of the literature]. / Angéite isolée du système nerveux central, deux nouveaux cas et revue de la littérature.

Isolated angiitis of the central nervous system is a rare disease affecting mainly adults of both sex; about 210 cases have been reported. Contrary to other inflammatory arteritis, arthralgia, myalgia, weight loss and fever are exceptional and symptoms are mainly neurologic, but none is specific. The diagnosis is evoked in case of headaches and cognitive impairment, associated or not with multifocal neurologic signs. Evolution is acute, subacute or chronic. Elevated sedimentation rate and cerebrospinal fluid pleiocytosis are present in 2/3 of cases. CT scan and brain MRI generally demonstrate multifocal ischemic lesions involving cortex, white matter, basal ganglia and brainstem. Cerebral arteriography is the key investigation, showing segmental stenoses alternating with fusiform dilatations of blood vessels, which are highly suggestive but not specific. It can be normal and its repetition is then recommended. Certain diagnosis is obtained from cerebromeningeal biopsy, showing a segmental angiitis of small vessels, which is granulomatous in 88 p.100 and non granulomatous in 12 p.100 of cases. The pathogenesis is unknown. Spontaneous evolution is generally fatal. Cyclophosphamide associated with prednisone considerably improves the prognosis, especially when initiated early in the course of the disease.

A single intracerebral microinjection of platelet-derived growth factor (PDGF) accelerates the rate of remyelination in vivo.

We had demonstrated that platelet-derived growth factor (PDGF) enhanced the reconstruction of myelin-like membranes after their disruption by lysophosphatidylcholine (LPC) in vitro. To investigate its role in vivo, a demyelinating lesion of the corpus callosum was induced in adult Wistar rats by a stereotaxic microinjection of 1 microl LPC, then 63 pairs of rats received either 1 microg PDGF, or its vehicle buffer which were injected above LPC. The effects of PDGF were significant after 2 weeks: the number of oligodendrocytes (OL) expressing 2',3'-cyclic nucleotide 3'-phosphodiesterase in the lesion increased by 49%, mature OL labelled by in situ hybridization for myelin basic protein-mRNA increased by 27% (P<10(-2)), and the total volume of demyelination decreased by 60% compared to controls. The proliferation of cells of the OL lineage was also enhanced up to 67% by PDGF compared to LPC controls (P<2.5 x 10(-2)). Ultrastructural studies confirmed this dramatic improvement, and the ratio of remyelinated to demyelinated axons, determined at the maximal demyelination site, in the centre of the lesion, increased by 10-fold (P<2.5 x 10(-3)) in animals treated with PDGF. Remyelination was complete after 3 months for both treatments. Neither exacerbation of gliosis nor glial tumoural transformation were observed. Mechanisms through which PDGF improves remyelination could involve proliferation of OL progenitors, and/or of already differentiated surviving OLs, and a chemotactic effect, which had been identified in vitro.

[Unusual complication of rendu-osler-weber disease: paramedian bulbar syndrome]. / Complication inhabituelle de la maladie de Rendu-Osler-Weber : le syndrome bulbaire paramédian.

We report a case of arteriovenous malformation of the brainstem, revealed by a progressive right pyramidal syndrome and an atrophy of the left hemi-tongue in a man presenting a Rendu-Osler-Weber disease. After embolization the clinical course was stationary.

Glutamine synthetase expression and activity are regulated by 3,5,3'-triodo-L-thyronine and hydrocortisone in rat oligodendrocyte cultures.

Glutamine synthetase plays a central role in the detoxification of brain ammonia. Previously, we demonstrated that in vitro glutamine synthetase is expressed by all macroglial cell types and is developmentally regulated in oligodendrocyte lineage. Furthermore, glutamine synthetase is increased in secondary cultures of oligodendrocytes following a 72 h treatment with 30 nM 3,5,3'-triodo-L-thyronine [Baas, D., Bourbeau, D., Sarliève, L. L., Ittel, M. E., Dussault, J. H. and Puymirat, J., Oligodendrocyte maturation and progenitor cell proliferation are independently regulated by thyroid hormone. Glia, 1997, 19, 324-332]. Hydrocortisone also increases glutamine synthetase activity after 72 h [Fressinaud, C., Weinrauder, H., Delaunoy, J. P., Tholey, G., Labourdette, G. and Sarliève, L. L., Glutamine synthetase expression in rat oligodendrocytes in culture: regulation by hormones and growth factors. J. Cell. Physiol., 1991, 149, 459-468]; however, it is still unknown whether these increases in glutamine synthetase expression in oligodendrocytes after 3,5,3'-triodo-L-thyronine and hydrocortisone application are dose- and time-dependent. To further investigate this issue, we measured glutamine synthetase levels by Northern analysis, immunostaining and determination of glutamine synthetase activity after 3,5,3'-triodo-L-thyronine or hydrocortisone stimulation. We find that in rat oligodendrocyte secondary cultures, 3,5,3'-triodo-L-thyronine and hydrocortisone cause a dose- and time-dependent increase in glutamine synthetase mRNA, protein and activity. However, these hormones do not exert an additive or synergistic effect. Because purines, pyrimidines, and certain amino acids necessary for the synthesis of myelin components, are, in part, provided by the glutamine synthetase pathway, 3,5,3'-triodo-L-thyronine effect on myelination development and maturation could be mediated in part, through the glutamine synthetase gene regulation.

Oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells express glutamine synthetase: developmental and cell type-specific regulation.

Glutamine synthetase (GS), the enzyme that catalyses glutamine synthesis from glutamate and ammonia, plays a central role in the detoxification of brain ammonia. In the central nervous system (CNS), GS also subserves additional important functions such as regulating glutamate, GABA and amino acid metabolism. Oligodendrocytes (OL) form the myelin sheath in the central nervous system (CNS) and are essential for efficient propagation of nerve impulses. In culture, OL arise from bipotential O-2A progenitor cells. These O-2A cells give rise to type-2 astrocytes in the presence of serum. GS is expressed in mature glial cells in vivo and in vitro, but it is unknown whether GS is present in glial progenitors. In addition, a comparison of the GS expression level among the various types of glial cells has never been done in vitro. The current study investigates in vitro GS expression levels in O-2A progenitors, astrocytes and OL. We demonstrate that the GS gene is expressed in O-2A progenitors and is expressed at different levels in each cultured glial cell type. GS also is stimulated during OL developmental maturation. Thus, the GS gene is expressed in O-2A cells and is regulated in a developmental and macroglial cell type-specific manner.

Platelet-derived growth factor partly prevents chemically induced oligodendrocyte death and improves myelin-like membranes repair in vitro.

We have previously shown that pure oligodendrocyte (OL) secondary cultures derived from newborn rat brain, in which cells form myelin-like membranes, can be used as a model to investigate the putative role of growth factors in myelin repair. After disruption of these membranes by lysophosphatidylcholine (LPC), a 3 day treatment with 10 ng/ml basic fibroblast growth factor (bFGF) induced reconstruction of myelin figures, albeit less compacted than in untreated controls. Here we show that in LPC treated cultures: 1) bFGF can not prevent OL from LPC-induced cell death; 2) platelet-derived growth factor (PDGF) pretreatment although preventing some cell death does not improve recovery compared to delayed treatment; 3) PDGF is as potent as bFGF in terms of O-2A progenitor proliferation; 4) PDGF is far more effective than bFGF, inducing the reappearance of more myelin-like structures with a better compaction; 5) there is no potentiation between these growth factors; and 6) after withdrawal of bFGF the compaction of myelin figures partly increases. These results indicate that PDGF, probably by inducing O-2A progenitors to proliferate and then allowing them to differentiate into mature myelinating OL, is a better candidate than bFGF to participate in myelin repair mechanisms in the central nervous system.

Basic fibroblast growth factor down-regulates myelin basic protein gene expression and alters myelin compaction of mature oligodendrocytes in vitro.

The effects of basic fibroblast growth factor (bFGF) on myelin basic protein (MBP) gene expression and myelin-like membrane formation were investigated in oligodendrocyte cultures containing mainly mature oligodendrocytes expressing MBP. These cultures were obtained by selective detachment of the cells of the oligodendrocyte lineage from 40-day-old mixed cultures derived from newborn rat brain. They were further purified by a 3-day pretreatment with cytosine arabinoside (ARA-C) in order to kill cycling cells. After withdrawal of ARA-C, daily treatment of the cells with bFGF for 3 days induced a drastic decrease in MBP mRNA level compared to control cultures treated only with ARA-C. Moreover, the percentage of oligodendrocytes labelled with anti-MBP antibodies decreased by 50%, as well as that of oligodendrocytes expressing myelin oligodendrocyte glycoprotein (MOG), whereas proteolipid protein (PLP) immunolabelled cells were less affected. At the ultrastructural level, myelin-like membranes were still abundant in the ARA-C- and bFGF-treated cultures, but they were conspicuously uncompacted compared to cultures only pretreated with ARA-C. These results bring the first evidence that bFGF is able to down-regulate myelin protein gene expression in mature oligodendrocytes and to alter myelin structure. They imply that if bFGF is secreted after a demyelinating lesion of the central nervous system (CNS), this plasticity of mature oligodendrocytes will allow final remyelination of axons to complete only after this factor has returned to low levels.

Expression of thyroid hormone receptor isoforms in rat oligodendrocyte cultures. Effect of 3,5,3'-triiodo-L-thyronine.

3,5,3'-Triiodo-L-thyronine (T3) acts at the genomic level by interacting with nuclear T3 receptors (T3Rs). We have used double immunostaining to follow the expression of T3Rs and oligodendrocytes (OL) lineage markers in rat secondary cultures consisting of 85-90% OL. Using antibodies against different synthetic peptides of T3Rs (alpha common: alpha 1 + alpha 2 and beta 1) we find that alpha-T3R is expressed in both O-2A progenitors and in mature OL, while beta 1-T3R is expressed only in mature OL. In cultured OL, beta 1-T3R mRNA is upregulated the most by T3. OL exhibit more numerous and longer processes when treated by T3.

Basic fibroblast growth factor improves recovery after chemically induced breakdown of myelin-like membranes in pure oligodendrocyte cultures.

The putative role of growth factors in remyelination was investigated in pure oligodendrocyte (OL) secondary cultures derived from newborn rat brain. These cells form myelin-like membranes and were used as a model system for toxic attack. A 24 hr treatment with 2.10(-5) M lysophosphatidylcholine (LPC) induced a loss of 59% of the cells in these cultures, with a 64% reduction in [125I]-iododeoxyuridine incorporation compared to untreated controls. An absence of processes and myelin-like sheaths was observed in the remaining cells. Numerous intracytoplasmic inclusions were observed on transmission electron microscopy. Immunocytochemical studies with A2B5 monoclonal antibody (mAb), which recognizes oligodendrocyte-type 2 astrocyte (O-2A) precursors, OL-1 mAb (directed against cell surface sulfatides), and anti-myelin basic protein (anti-MBP) antibody showed that the entire OL lineage was affected at all stages of maturation. A 3 day treatment with 10 ng/ml basic fibroblast growth factor (bFGF) induced reconstruction of myelin-like membranes, albeit less compacted than in untreated controls. The doubling in number of cells and the 46% increase in [125I]-iododeoxyuridine incorporation was due essentially to proliferation of O-2A progenitors. These results indicate that if bFGF release occurs during demyelination, it may participate in myelin repair mechanisms in the central nervous system.

The proliferation of mature oligodendrocytes in vitro is stimulated by basic fibroblast growth factor and inhibited by oligodendrocyte-type 2 astrocyte precursors.

Basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) are mitogens for bipotential oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells. We investigated the mitogenic effect of these growth factors on quiescent mature oligodendrocytes (OL) expressing myelin basic protein (MBP) in OL cultures that were treated for 3 days with cytosine arabinoside (ARA-C) in order to kill O-2A precursors which divide in chemically defined medium. After treatment with ARA-C proliferation decreased and O-2A precursors identified with A2B5 monoclonal antibody were nearly undetectable. After exposure of mature OL to bFGF, cell proliferation increased markedly within 24 hr. PDGF had a much weaker effect. Cultures treated with ARA-C for 3 days and then with bFGF for the next 24 hr and incubated with BrdU for the last 2 hr before the end of the experiment were immunolabeled with anti-MBP or A2B5 and anti-bromodeoxyuridine (BrdU) antibodies. Eighty-seven percent of the cells were MBP+, 10% were both MBP+ and BrdU+, and none was A2B5+ BrdU+, showing that at least a part of the population of mature MBP+ OL retains the ability to reenter the cell cycle in vitro. Since mature OL did not proliferate in response to bFGF in the cultures not treated with ARA-C, i.e., in the presence of O-2A progenitors, we assumed that these precursors were responsible for the lack of mitogenic effect of bFGF on MBP+ OL in such conditions. Conditioned medium from O-2A precursors almost halved the bFGF-induced OL proliferation after treatment with ARA-C, suggesting that O-2A progenitors control the proliferation of a subpopulation of mature OL (possibly young mature OL) via the secretion of active molecule(s).

[Familial complex myxoma-lentiginosis disclosed by probable transient ischemic accident]. / Complexe familial myxome-lentiginose révélé par un probable accident ischémique transitoire.

A probable transient ischemic attack in a 45-year-old woman revealed bilateral atrial myxoma associated with lentiginosis. The patient's 20-year-old son had isolated lentiginosis. The characteristics of this autosomal dominant syndrome are reviewed.

Adult-onset metachromatic leukodystrophy presenting as isolated peripheral neuropathy.

A 38-year-old man presented with weakness of the lower limbs. Electrophysiology revealed a pronounced demyelinating neuropathy. Nerve biopsy disclosed de- and remyelinating lesions and characteristic lamellar inclusions in Schwann cells and macrophages. There was no familial history of neurologic disorder, and impairment of motor evoked potentials was the only sign of CNS involvement. Arylsulfatase A and cerebroside sulfate sulfatase activities in leukocytes and cultures of the patient's fibroblasts were low. The sulfatide loading test also revealed abnormal sulfatide accumulation. This may be the first reported case of adult metachromatic leukodystrophy presenting as peripheral neuropathy.

Differential regulation of cerebroside sulfotransferase and 2',3'-cyclic nucleotide 3'-phosphodiesterase by basic fibroblast growth factor in relation to proliferation in rat oligodendrocyte cultures.

Previous results (Fressinaud, C., Sarliève, L.L., and Labourdette, G. J. J. Cell. Physiol., 141:667-674, 1989b) have shown that cerebroside sulfotransferase (CST; EC 2.8.2.11) is enriched in pure rat oligodendrocyte (OL) cultures and that its activity is increased by factors mitogenic for OL precursors and galactocerebroside (GC) expressing OL, such as basic fibroblast growth factor (bFGF), platelet-derived growth factor, and high insulin concentrations. In contrast, transforming growth factor beta or low insulin concentrations were found to be ineffective in this culture system. As bFGF mainly enhanced the proliferation of OL precursors (GC negative cells) rather than that of differentiated (GC+) cells, a relationship between OL precursor proliferation and CST increase was suggested. This hypothesis was first tested in 20-day-old OL cultures grown in chemically defined medium. The dose-response curve of [125I] Iododeoxyuridine ([125I]dUrd) incorporation toward bFGF was parallel to that of CST specific activity, and maximal stimulation was reached at 5 ng/ml bFGF for both. In contrast, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP; EC 3.1.4.37) specific activity decreased after bFGF treatment. To determine if CST increase was linked to the proliferation of OL precursors induced by bFGF, cell proliferation was blocked by cytosine arabinoside (ARA-C). From 10(-8) to 10(-5) M ARA-C there was a dose-dependent inhibition of cell proliferation and a decrease in CST specific activity, whereas CNP specific activity was enhanced. When the cells were treated with bFGF and 10(-6) M ARA-C together, the proliferation was completely blocked and CST activity decreased by 72% below control values, whereas CNP activity was not significantly decreased. Immunocytochemical studies showed that the number of sulfatide-expressing cells and the number of cycling cells were increased after bFGF treatment, but that there was no overlapping between these two populations. Taken together these results suggest that CST activity and sulfatide expression appear shortly after the arrest of OL precursor division.

Glutamine synthetase expression in rat oligodendrocytes in culture: regulation by hormones and growth factors.

Glutamine synthetase (GS, EC 6.3.1.2.) has long been considered as a protein specific for astrocytes in the brain, but recently GS immunoreactivity has been reported in oligodendrocytes both in mixed primary glial cell cultures and in vivo. We have investigated its expression and regulation in "pure" oligodendrocyte cultures. "Pure" oligodendrocyte secondary cultures were derived from newborn rat brain primary cultures enriched in oligodendrocytes as described by Besnard et al. (1987) and were grown in chemically defined medium. These cultures contain more than 90% galactocerebroside-positive oligodendrocytes and produce "myelin" membranes (Fressinaud et al., 1990) after 6-10 days in subcultures (30-35 days, total time in culture). The presence of GS in oligodendrocytes from both primary glial cell cultures and "pure" oligodendrocyte cultures was confirmed by double immunostaining with a rabbit antisheep GS and guinea pig antirat brain myelin 2', 3'-cyclic nucleotide 3'-phosphodiesterase. In "pure" oligodendrocyte cultures, about half of cells were labeled with anti-GS antibody. Furthermore, on the immunoblot performed with a rabbit antisheep GS, the GS protein in "pure" oligodendrocyte secondary cultures was visualized as a single band with an apparent molecular mass of about 43 kDa. In contrast, two protein bands for GS were observed in cultured astrocytes. On the immunoblot performed with a rabbit antichick GS, two immunopositive protein bands were observed: a major one migrating as the purified adult chick brain GS and a minor one with a lower molecular mass. Two similar immunoreactive bands were also observed in pure rat astrocyte cultures. Compared to pure rat astrocyte cultures, "pure" oligodendrocyte cultures of the same age displayed an unexpectedly high GS specific activity that could not be explained by astrocytic contamination of the cultures (less than 5%). As for cultured astrocytes, treatment of oligodendrocyte cultures with dibutyryl-adenosine 3':5'-cyclic monophosphate, triiodothyronine, or hydrocortisone increased significantly GS specific activity. Interestingly, epidermal growth factor, basic fibroblast growth factor, and platelet-derived growth factor that increase the GS activity in astrocytes do not affect this activity in oligodendrocytes. Thus we confirm the finding of Warringa et al. (1988) that GS is also expressed in oligodendrocytes. We show that its activity is regulated similarly in astrocytes and oligodendrocytes by hormones, but that it is regulated differently by growth factors in these two cell types.

Homocystinuria due to 5,10-methylenetetrahydrofolate reductase deficiency revealed by stroke in adult siblings.

Three patients from a single family of six siblings had homocystinemia and homocystinuria due to 5,10-methylenetetrahydrofolate reductase deficiency and had severe recurrent strokes in adult life. Two of the patients died 1 year after clinical onset.