[The role of PET-CT in decision making on the treatment of localized nodular form of pulmonary AL-amyloidosis]. / Prínos PET-CT vysetrení pro rozhodování o lécbe lokalizované nodulární formy plicní AL-amyloidózy.

Depending on the extent of organism affected, there is a systemic (amyloid is deposited in the interstitial space of multiple tissues and organs) and localized (amyloid is deposited in one or a few solitary lesions) form of amyloidosis. Localized forms of amyloidosis have a significantly better prognosis than the systemic ones. The respiratory tract might be affected by diffuse interstitial involvement, associated with systemic AL-amyloidosis, as well as localised involvement of respiratory tract (localised laryngotracheobronchial amyloidosis) or pulmonary parenchyma called nodular form of localized pulmonary amyloidosis. Tracheobronchial form may affect larynx and bronchial tree, and forms plaques or nodules in the epithelium of the respiratory tract. Nodular form causes spherical or irregular lesions in the pulmonary parenchyma, indistinguishable from pulmonary parenchyma metastases. We describe a two-year follow up of a patient with nodular form of pulmonary amyloidosis. The patient had multiple lesions in both lungs, clearly visible on HRCT (High Resolution Computer Tomography) that intensively accumulated fluorodeoxyglucose (FDG) during the first PET-CT. At the time of diagnosis, the largest lesion SUV for FDG accumulation was 8.2. Histochemical analysis showed that amyloid consisted of the light λ chains, i.e. AL-amyloid. Investigations to detect a systemic form of amyloidosis, if present, were negative. The patient had no monoclonal immunoglobulin either in the urine or serum (negative immunofixation) and had normal levels of free light chains in the serum. Her symptoms were previously suggestive of the Sjögrens syndrome. However, the rheumatologist consulted at the time of diagnosis of the nodular form of pulmonary amyloidosis did not find any signs of an active systemic connective tissue disorder. CRP was repeatedly normal. When systemic AL-amyloidosis was excluded, we decided to only monitor lesion development with no treatment intervention. The patient had 3 PET-CTs. CT showed that no lesions enlarged, some lesions decreased in size slightly. It should be emphasized that follow-up PET-CTs did not show increased FDG accumulation. We assume that the increased FDG accumulation in pulmonary lesions seen during the first PET-CT was due to the activity of the cells that formed this amyloid and that this activity spontaneously ceased, leading to normalization of FDG accumulation in pulmonary nodules. PET-CT is useful for monitoring of the development of pulmonary nodular amyloidosis. Normalization of originally increased FDG accumulation in amyloid lesions suggests cessation of the process of amyloid formation and is a positive prognostic sign.

Danon disease: a focus on processing of the novel LAMP2 mutation and comments on the beneficial use of peripheral white blood cells in the diagnosis of LAMP2 deficiency.

Danon disease (DD) is a monogenic X-linked disorder characterized by cardiomyopathy, skeletal myopathy and variable degrees of intellectual disability. DD develops due to mutations in the gene encoding lysosomal-associated membrane protein 2 (LAMP2). We report on a family exhibiting the clinical phenotype comprising of hypertrophic cardiomyopathy and ventricular pre-excitation, myopia and mild myopathy in two male patients and cardiomyopathy and myopia in a female patient. The diagnosis of DD in this family was based on the assessment of the clinical phenotypes and the absence of LAMP2 in skeletal and/or cardiac muscle biopsy specimens. Sequence analysis of the LAMP2 gene and its mRNA revealed a novel LAMP2 mutation (c.940delG) in all three patients. Approximately 25% of the female patient's cardiomyocytes were LAMP2 positive apparently due to the unfavorable skewing of X chromosome inactivation. We further performed qualitative LAMP2 immunohistochemistry on peripheral white blood cells using the smear technique and revealed the absence of LAMP2 in the male patients. LAMP2 expression was further assessed in granulocytes, CD4+ and CD8+ T lymphocytes, CD20+ B lymphocytes, CD14+ monocytes and CD56+ natural killer cells by quantitative polychromatic flow cytometry. Whereas the male DD patients lacked LAMP2 in all WBC populations, the female patient expressed LAMP2 in 15.1% and 12.8% of monocytes and granulocytes, respectively. LAMP2 expression ratiometrics of highly vs. weakly expressing WBC populations discriminated the DD patients from the healthy controls. WBCs are thus suitable for initial LAMP2 expression testing when DD is a differential diagnostic option. Moreover, flow cytometry represents a quantitative method to assess the skewing of LAMP2 expression in female heterozygotes. Because LAMP2 is a major protein constituent of the membranes of a number of lysosome-related organelles, we also tested the exocytic capacity of the lytic granules from CD8+ T lymphocytes in the patient samples. The degranulation triggered by a specific stimulus (anti-CD3 antibody) was normal. Therefore, this process can be considered LAMP2 independent in human T cells. The c.940delG mutation results in a putatively truncated protein (p.A314QfsX32), which lacks the transmembrane domain and the cytosolic tail of the wild-type LAMP2. We tested whether this variant becomes exocytosed because of a failure in targeting to late endosomes/lysosomes. Western blotting of cardiac muscle, WBCs and cultured skin fibroblasts (and their culture media) showed no intra- or extracellular truncated LAMP2. By comparing the expression pattern and intracellular targeting in cultured skin fibroblasts of normal LAMP2 isoforms (A, B and C) tagged with green fluorescent protein (GFP) and the A314Qfs32-GFP fusion, we found that the A314Qfs32-GFP protein is not even expressed. These observations suggest that the truncated protein is unstable and is co-translationally or early post-translationally degraded.

Clinical and molecular characterization of a family with a dominant renin gene mutation and response to treatment with fludrocortisone.

BACKGROUND: A family was identified with autosomal dominant inheritance of anemia, polyuria, hyperuricemia, and chronic kidney disease. Mutational analysis revealed a novel heterozygous mutation c.58T > C resulting in the amino acid substitution of cysteine for arginine in the preprorenin signal sequence (p.cys20Arg) occurring in all affected members. METHODS: Effects of the identified mutation were characterized using in vitro and in vivo studies. Affected individuals were clinically characterized before and after administration of fludrocortisone. RESULTS: The mutation affects endoplasmic reticulum co-translational translocation and posttranslational processing, resulting in massive accumulation of non-glycosylated preprorenin in the cytoplasm. This affects expression of intra-renal RAS components and leads to ultrastructural damage of the kidney. Affected individuals suffered from anemia, hyperuricemia, decreased urinary concentrating ability, and progressive chronic kidney disease. Treatment with fludrocortisone in an affected 10-year-old child resulted in an increase in blood pressure and estimated glomerular filtration rate. CONCLUSIONS: A novel REN gene mutation resulted in an alteration in the amino acid sequence of the renin signal sequence and caused childhood anemia, polyuria, and kidney disease. Treatment with fludrocortisone improved renal function in an affected child. Nephrologists should consider REN mutational analysis in families with autosomal dominant inheritance of chronic kidney disease, especially if they suffer from anemia, hyperuricemia, and polyuria in childhood.

Expression and lysosomal targeting of CLN7, a major facilitator superfamily transporter associated with variant late-infantile neuronal ceroid lipofuscinosis.

Neuronal ceroid lipofuscinoses (NCLs) constitute a group of progressive neurodegenerative disorders resulting from mutations in at least eight different genes. Mutations in the most recently identified NCL gene, MFSD8/CLN7, underlie a variant of late-infantile NCL (vLINCL). The MFSD8/CLN7 gene encodes a polytopic protein with unknown function, which shares homology with ion-coupled membrane transporters. In this study, we confirmed the lysosomal localization of the native CLN7 protein. This localization of CLN7 is not impaired by the presence of pathogenic missense mutations or after genetic ablation of the N-glycans. Expression of chimeric and full-length constructs showed that lysosomal targeting of CLN7 is mainly determined by an N-terminal dileucine motif, which specifically binds to the heterotetrameric adaptor AP-1 in vitro. We also show that CLN7 mRNA is more abundant in neurons than astrocytes and microglia, and that it is expressed throughout rat brain, with increased levels in the granular layer of cerebellum and hippocampal pyramidal cells. Interestingly, this cellular and regional distribution is in good agreement with the autofluorescent lysosomal storage and cell loss patterns found in brains from CLN7-defective patients. Overall, these data highlight lysosomes as the primary site of action for CLN7, and suggest that the pathophysiology underpinning CLN7-associated vLINCL is a cell-autonomous process.

Oligodendroglia from ADSL-deficient patient produce SAICAribotide and SAMP.

Succinylpurines accumulate in the body fluids of patients with adenylosuccinate lyase (ADSL) deficiency but their source in the cerebrospinal fluid remains obscure. Study based on the incorporation of 13C-stable isotope-labeled glycine into cultured oligodendroglia from ADSL-deficient patient and the measurement of labeled products by LC/MS/MS showed total intracellular concentrations of succinylpurines from 45 to 99µmol/l and so these results suggest that these cells can be the source of the compounds in vivo.

Histochemical detection of GM1 ganglioside using cholera toxin-B subunit. Evaluation of critical factors optimal for in situ detection with special emphasis to acetone pre-extraction.

A comparison of histochemical detection of GM1 ganglioside in cryostat sections using cholera toxin B-subunit after fixation with 4% formaldehyde and dry acetone gave tissue-dependent results. In the liver no pre-treatment showed detectable differences related to GM1 reaction products, while studies in the brain showed the superiority of acetone pre-extraction (followed by formaldehyde), which yielded sharper images compared with the diffuse, blurred staining pattern associated with formaldehyde. Therefore, the aim of our study was to define the optimal conditions for the GM1 detection using cholera toxin B-subunit. Ganglioside extractability with acetone, the ever neglected topic, was tested comparing anhydrous acetone with acetone containing admixture of water. TLC analysis of acetone extractable GM1 ganglioside from liver sections did not exceed 2% of the total GM1 ganglioside content using anhydrous acetone at -20 degrees C, and 4% at room temperature. The loss increased to 30.5% using 9:1 acetone/water. Similarly, photometric analysis of lipid sialic acid, extracted from dried liver homogenates with anhydrous acetone, showed the loss of gangliosides into acetone 3.0 +/- 0.3% only. The loss from dried brain homogenate was 9.5 +/- 1.1%. Thus, anhydrous conditions (dry tissue samples and anhydrous acetone) are crucial factors for optimal in situ ganglioside detection using acetone pre-treatment. This ensures effective physical fixation, especially in tissues rich in polar lipids (precipitation, prevention of in situ diffusion), and removal of cholesterol, which can act as a hydrophobic blocking barrier.

Autopsy case of Gaucher disease type I in a patient on enzyme replacement therapy. Comments on the dynamics of persistent storage process.

We report a female patient with Gaucher disease (GD) type I on ERT (imiglucerase) for 5 years, which led to a significant general improvement. Aged 59 years she underwent an episode of altitude sickness followed by sepsis, disseminated intravascular coagulation, and multiorgan failure. She succumbed to a cerebral haemorrhage. Autopsy revealed liver cholestatic cirrhosis and multifocal liver carcinoma with immunophenotype compatible with cholangiocarcinoma. Analysis of the storage process revealed its absence or very low levels in the majority of liver and spleen macrophages. Gaucher cells (GCs) were seen only as occasional aggregates of various sizes in these organs. GCs were seen also in the leptomeninx of the cerebellum and as infrequent perivascular clusters in both the grey and white cerebral matters. Bone marrow was heavily infiltrated with GCs, especially in the adipocyte-rich part. GCs in this location displayed varied degrees of cytoplasmic vacuolation unrelated to the lysosomal compartment, caused by droplets of triglyceride, and interpreted as due to resorption of fragments of altered white adipocytes. All these observations point to the relative efficacy of ERT in covering the standard substrate load, which should not be exceeded as it would lead to the evolution of mature GCs. The results are discussed in relation to our recently published hypothesis on GD cell pathology.

[The isolated form of cardiac amyloidosis in the form of beginning infiltrative cardiomyopathy without restrictive physiology]. / Izolovaná forma srdecní amyloidózy v podobe pocínající infiltrativní kardiomyopatie bez restriktivní fyziologie.

The authors describe an interesting case of isolated cardiac manifestation of AL-amyloidosis manifesting as an incipient infiltrative cardiomyopathy with heart failure symptoms due to moderate left ventricular diastolic dysfunction. Restrictive cardiomyopathy with severe diastolic dysfunction is considered as the characteristic manifestation of fully developed cardiac amyloidosis. However, the organ deposition of amyloid is progressive and left ventricular filling worsens continuously, starting with less advanced forms of diastolic dysfunction; the restrictive physiology is characteristic only for advanced phases of the disease. Therefore, the possibility of the incipient infiltrative cardiomyopathy due to the amyloidosis should be considered in patients with heart failure symptoms and echocardiographic findings of unexplained left ventricular hypertrophy with only mild or moderate diastolic dysfunction.

Intravascular ultrasound assessment of coronary artery involvement in Fabry disease.

AIM: We used intravascular ultrasound (IVUS) to characterize coronary artery involvement in patients with Fabry disease (FD). METHODS: Nine FD patients (5 women) were matched to 10 control patients (5 women) chosen from our IVUS database. Standard volumetric IVUS analyses were performed along with assessment of plaque echodensity. RESULTS: Plaques in FD patients were diffuse and hypoechogenic compared with more focal and more echogenic lesions in control patients. Echogenicity of plaques was significantly lower in FD patients (median 30.7 +/- 12.9 vs 55.9 +/- 15.7, p = 0.0052, mean 37.2 +/- 15.6 vs 66.2 +/- 13.3, p = 0.0014). Diffusiveness was assessed as differences between mean and median plaque burden versus the plaque burden in each of the analysed cross-sections. These differences were lower in FD vs controls (5.8 +/- 4.8 vs 8.7 +/- 6.6, p < 0.001 for mean, and 5.8 +/- 4.9 vs 8.8 +/- 7.3, p < 0.001 for median) indicating a more diffuse involvement. The occurrence of lipid cores was significantly higher in FD patients than in controls (2.4 +/- 1.5 vs 1.0 +/- 0.94, p = 0.02). CONCLUSION: IVUS showed diffuse hypoechogenic plaques in patients with FD. The explanation may be higher lipid content in plaques and accumulation of glycosphingolipid in smooth-muscle and endothelial cells.

Abnormal expression and processing of uromodulin in Fabry disease reflects tubular cell storage alteration and is reversible by enzyme replacement therapy.

Uromodulin (UMOD) malfunction has been found in a range of autosomal dominant tubulointerstitial nephropathies associated with hyperuricaemia, gouty arthritis, medullary cysts and renal failure-labelled as familial juvenile hyperuricaemic nephropathy, medullary cystic disease type 2 and glomerulocystic kidney disease. To gain knowledge of the spectrum of UMOD changes in various genetic diseases with renal involvement we examined urinary UMOD excretion and found significant quantitative and qualitative changes in 15 male patients at various clinical stages of Fabry disease. In untreated patients, the changes ranged from normal to a marked decrease, or even absence of urinary UMOD. This was accompanied frequently by the presence of aberrantly processed UMOD lacking the C-terminal part following the K432 residue. The abnormal patterns normalized in all patients on enzyme replacement therapy and in some patients on substrate reduction therapy. Immunohistochemical analysis of the affected kidney revealed abnormal UMOD localization in the thick ascending limb of Henle's loop and the distal convoluted tubule, with UMOD expression inversely proportional to the degree of storage. Our observations warrant evaluation of tubular functions in Fabry disease and suggest UMOD as a potential biochemical marker of therapeutic response of the kidney to therapy. Extended comparative studies of UMOD expression in kidney specimens obtained during individual types of therapies are therefore of great interest.

Early onset Alexander disease: a case report with evidence for manifestation of the disorder in neurohypophyseal pituicytes.

We report the first case of Alexander disease diagnosed and published in the region of former Czechoslovakia. The case was characterized by early (late infantile) onset, the absence of megacephaly but with extensive internal hydrocephaly, despite a patent aqueduct. Neuropathology revealed severe depletion ofoligodendroglia and myelin, loss of axons, prominent astrocytosis with massive intracellular, dense globular GFAP aggregates which differed from typical Rosenthal fibers. Additionally, many large aggregates of GFAP were located extracellularly. Globular GFAP aggregates were also identified in neurohypophyseal pituicytes. DNA analysis disclosed a heterozygous mutation c.1117G>A in the GFAP, which is predicted to lead to the amino acid exchange p.Glu-373Lys (E373K) in the C-terminal tail of the GFAP protein. The parents and a healthy sister did not show any variation in GFAP in somatic cells.

A case of excessive autophagocytosis with multiorgan involvement and low clinical penetrance.

An autopsy and microscopic analyses of a 74-year-old female with a clinical history of cardiac hypertrophy and hypertension disclosed a pronounced distension of lysosomal compartment with signs of excessive autophagocytosis, predominantly in cardiomyocytes, hepatocytes and smooth muscle cells of the small intestine. The histological storage pattern did not correspond to the usual changes seen in defined lysosomal storage disorders. The amount of age-related lipopigment was low in all tissues. Confocal microscopy of liver tissue samples documented a progressive loss of mitochondrial epitopes in the distended lysosomal compartment along the porto-central axis of hepatic lobules. The possibility to detect subunit c of mitochondrial ATP synthase (SCMAS) indicated extensive intra-lysosomal degradation of mitochondria, both in hepatocytes and smooth muscle cells. The SCMAS epitope can thus be considered a valuable immunohistochemical marker of autophagocytic mitochondrial degradation. The distended lysosomes also displayed tissue specific ubiquitination. Absence of immuno-detectable p62 protein excluded aggresome formation. An inherent dysfunction of the late endosomal/lysosomal LAMP2 protein (Danon disease), was excluded on the basis of LAMP2 gene sequence analysis and LAMP2 protein levels. Whether the observed process reflects a primary dysregulation of the constitution of the autophagosomal membrane or was induced by defects in other cellular components, remains unanswered. Whatever mechanism involved, the findings should be considered relevant in differential diagnostics, despite their low clinical penetrance, should be registered and thus rendered available for future definition.

Glucosylceramide transfer from lysosomes--the missing link in molecular pathology of glucosylceramidase deficiency: a hypothesis based on existing data.

Gaucher disease (GD), deficiency of acid glucosylceramidase (GlcCer-ase) is characterized by deficient degradation of beta-glucosylceramide (GlcCer). It is well known that, in GD, the lysosomal accumulation of uncleaved GlcCer is limited to macrophages, which are gradually converted to storage cells with well known cytology--Gaucher cells (GCs). On the basis of previous studies of the disorder and of a comparison with other lysosomal enzymopathies affecting degradation of the GlcCer-based glycosphingolipid series, it is hypothesized that in other cell types (i.e. non-macrophage cells) the uncleaved GlcCer, in GlcCer-ase deficiency, is transferred to other cell compartments, where it may be processed and even accumulated to various degrees. The consequence of the abnormal extralysosomal load may differ according to the cell type and compartment targeted and may be influenced by genetically determined factors, by a number of acquired conditions, including the current metabolic situation. The sequelae of the uncleaved GlcCer extralysosomal transfer may range from probably innocent or positive stimulatory, to the much more serious, in which it interferes with a variety of cell functions, and in extreme cases, can lead to cell death. This alternative processing of uncleaved GlcCer may help to explain tissue alterations seen in GD that have, so far, resisted explanation based simply on the presence of GCs. Paralysosomal alternative processing may thus go a long way towards filling a long-standing gap in the understanding of the molecular pathology of the disorder. The impact of this alternative process will most likely be inversely proportional to the level of residual GlcCer-ase activity. Lysosomal sequestration of GlcCer in these cells is either absent or in those exceptional cases where it does occur, it is exceptional and rudimentary. It is suggested that paralysosomal alternative processing of uncleaved GlcCer is the main target for enzyme replacement therapy. The mechanism responsible for GlcCer transfer remains to be elucidated. It may also help in explaining the so far unclear origin of glucosylsphingosine (GlcSph) and define the mutual relation between these two processes.

Alterations of uromodulin biology: a common denominator of the genetically heterogeneous FJHN/MCKD syndrome.

Autosomal dominant hyperuricemia, gout, renal cysts, and progressive renal insufficiency are hallmarks of a disease complex comprising familial juvenile hyperuricemic nephropathy and medullary cystic kidney diseases type 1 and type 2. In some families the disease is associated with mutations of the gene coding for uromodulin, but the link between the genetic heterogeneity and mechanism(s) leading to the common phenotype symptoms is not clear. In 19 families, we investigated relevant biochemical parameters, performed linkage analysis to known disease loci, sequenced uromodulin gene, expressed and characterized mutant uromodulin proteins, and performed immunohistochemical and electronoptical investigation in kidney tissues. We proved genetic heterogeneity of the disease. Uromodulin mutations were identified in six families. Expressed, mutant proteins showed distinct glycosylation patterns, impaired intracellular trafficking, and decreased ability to be exposed on the plasma membrane, which corresponded with the observations in the patient's kidney tissue. We found a reduction in urinary uromodulin excretion as a common feature shared by almost all of the families. This was associated with case-specific differences in the uromodulin immunohistochemical staining patterns in kidney. Our results suggest that various genetic defects interfere with uromodulin biology, which could lead to the development of the common disease phenotype. 'Uromodulin-associated kidney diseases' may be thus a more appropriate term for this syndrome.

Subclinical course of adult visceral Niemann-Pick type C1 disease. A rare or underdiagnosed disorder?

We present the third case of Niemann-Pick disease type C without neurological symptoms. The patient was a 53-year-old woman without significant prior health problems who died of acute pulmonary embolism. Autopsy findings of hepatosplenomegaly, lymphadenopathy and ceroid-rich foam cells raised the suspicion of the visceral form of acid sphingomyelinase deficiency (Niemann-Pick disease type B; NPB) or a much rarer disorder, variant adult visceral form of Niemann-Pick disease type C (NPC). To verify the histopathological findings, SMPD1, NPC1 and NPC2 genes were analysed. Two novel sequence variants, c.1997G>A (S666N) and c.2882A>G (N961S) were detected in the NPC1 gene. No pathogenic sequence variants were found either in the SMPD1 gene mutated in NPB or in NPC2 gene. The pathogenicity of both NPC1 variants was supported by their location in regions important for the protein function. Both variations were not found in more than 300 control alleles. Identified sequence variations confirm the diagnosis of the extremely rare adult visceral form of Niemann-Pick disease type C, which is otherwise dominated by neurovisceral symptoms. Although only three patients have been reported, this (most probably underdiagnosed) form of NPC should be considered in differential diagnosis of isolated hepatosplenomegaly with foam cells in adulthood.

Prosaposin deficiency -- a rarely diagnosed, rapidly progressing, neonatal neurovisceral lipid storage disease. Report of a further patient.

An infant presented with multifocal myoclonus and cyanotic hypoxemia immediately after birth, and severe feeding problems, a protein-losing enteropathy, massive ascites and grand-mal epilepsy marked his rapid downhill course, with death at 17 weeks. At 2 weeks, brain MRI revealed grey matter heterotopias in the parieto-occipital regions suggestive of a cortical morphogenetic disorder. In cultured skin fibroblasts, lipid storage and reduced activities of ceramidase, galactosylceramide beta-galactosidase and glucosylceramide beta-glucosidase were evident. Autopsy disclosed generalised lysosomal lipid storage with macrophages and adrenal cortex prominently affected. The pattern of stored lipids in cultured fibroblasts and in dewaxed spleen tissue blocks was compatible with a diagnosis of prosaposin (pSap) deficiency (pSap-d). Neuropathologically, there was a pronounced generalised neurolysosomal storage combined with a severe depletion of cortical neurons and extreme paucity of myelin and oligodendroglia. This pathology, in particular the massive neuronal loss, differed from that in other neurolipidoses and could be explained by the reduced hydrolysis of multiple sphingolipids and the loss of pSap's neurotrophic function. The absence of immunostainable saposins on tissue sections and the presence of a homozygous c.1 A > T mutation in the prosaposin gene confirmed the diagnosis. PSap-d may be an underdiagnosed condition in infants with severe neurological and dystrophic signs starting immediately after birth.

Acid sphingomyelinase deficiency. Phenotype variability with prevalence of intermediate phenotype in a series of twenty-five Czech and Slovak patients. A multi-approach study.

A multi-approach study in a series of 25 Czech and Slovak patients with acid sphingomyelinase deficiency revealed a broad phenotypic variability within Niemann-Pick disease types A and B. The clinical manifestation of only 9 patients fulfilled the historical classification: 5 with the rapidly progressive neurovisceral infantile type A and 4 with a slowly progressive visceral type B. Sixteen patients (64%) represented a hitherto scarcely documented 'intermediate type' (IT). Twelve patients showed a protracted neurovisceral course with overt or mild neurological symptoms, three a rapidly progressing fatal visceral affection with rudimentary neurological lesion. One patient died early from a severe visceral disease. The genotype in our patients was represented by 4 frameshift and 14 missense mutations. Six were novel (G166R, R228H, A241V, D251E, D278A, A595fsX601). The Q292K mutation (homoallelic, heteroallelic) was strongly associated with a protracted neurovisceral phenotype (10 of 12 cases). The sphingomyelin loading test in living fibroblasts resulted in total degradation from less than 2% in classical type A to 70-80% in classical type B. In the IT group it ranged from 5% to 49% in a 24 h chase. The liver storage showed three patterns: diffuse, zonal (centrolobular), and discrete submicroscopic. Our series showed a notable variability in both the neurological and visceral lesions as well as in their proportionality and synchrony, and demonstrates a continuum between the historical 'A' and 'B' phenotypes of ASM deficiency. This points to a broad phenotypic potential of ASM deficiency, suggesting the existence of still unknown factors independently controlling the storage level in the visceral and neuronal compartments. This report highlights the important position of the IT in the ASM deficiency phenotype classification. We define IT as a cluster of variants combining clinical features of both the classical types. The protracted neuronopathic variant with overt, borderline or subclinical neurology prevails and is important in view of future enzyme replacement therapy. It appears more common in central Europe. The visceral, rapidly progressing early fatal type has been recognized rarely so far.

Lactosylceramide in lysosomal storage disorders: a comparative immunohistochemical and biochemical study.

Immunohistochemical studies of the presence of lactosylceramide (LacCer) in lysosomal storage disorders (LSDs) were done using anti-LacCer monoclonal antibody of the CDw 17 type (clone MG-2). No sign of an association between LacCer and the lysosomal system in normal cells was observed, except for histiocytes active in phagocytosis. A comparative study of a group of LSDs showed a general tendency for LacCer to increase in storage cells in Niemann-Pick disease type C (NPC), and types A and B, GM1 gangliosidosis, acid lipase deficiency, glycogen storage disease type II and mucopolysaccharidoses. LacCer accumulated in storage cells despite normal activity of relevant lysosomal degrading enzymes. The accumulation of LacCer displayed variability within storage cell populations, and was mostly expressed in neurons in NPC. An absence of the increase in LacCer in storage cells above control levels was seen in neuronal ceroid lipofuscinoses (neurons and cardiocytes) and in Fabry disease. Gaucher and Krabbe cells showed significantly lower levels, or even the absence, of LacCer compared with control macrophages. Results of immunohistochemistry were corroborated by semiquantitative lipid thin-layer chromatography (TLC). It is suggested that different associations of LacCer with the lysosomal storage process may reflect differences in glycosphingolipid turnover induced by the storage-compromised lysosomal/endosomal system.