Milan Elleder

Cardiocyte storage and hypertrophy as a sole manifestation of Fabry's disease. Report on a case simulating hypertrophic non-obstructive cardiomyopathy.

Fabrys disease was diagnosed in an adult patient as a lipid storage-induced non-obstructive hypertrophic cardiomyopathy. Stable angina pectoris started 15 years before death, was followed by slowly progressive heart failure and repeated pulmonary thromboembolism with death at 63 years. Autopsy disclosed enormous cardiomegaly (1100 g), cardiac storage of ceramide trihexoside (CTH) of the same intensity as in classical cases of generalized Fabrys disease (11 mg lipid/g wet weight) restricted to cardiocytes. Other tissues (liver, kidney, brain, pancreas, pulmonary artery, coronary arteries) were free of storage. Using proton magnetic resonance analysis on formaldehyde-fixed tissue the stored CTH was identified as globotriaosylceramide. It was enzymatically degradable by control cell cultures but left uncleaved by mutant reference Fabry cells. Alpha — galactosidase activities in peripheral leucocytes of all four of the patients daughters were in the heterozygous range. The diagnostic difficulties in this monosymptomatic novel variant of Fabrys disease are stressed.

Niemann-Pick Disease Type C: Spectrum of HE1 Mutations and Genotype/Phenotype Correlations in the NPC2 Group

In Niemann-Pick disease type C (NPC), a genetic heterogeneity with two complementation groups--NPC1, comprising > or =95% of the families, and NPC2--has been demonstrated. Mutations in the NPC1 gene have now been well characterized. HE1 was recently identified as the gene underlying the very rare NPC2. Here we report the first comprehensive study of eight unrelated families with NPC2, originating from France, Algeria, Italy, Germany, the Czech Republic, and Turkey. These cases represent essentially all patients with NPC2 who have been reported in the literature, as well as those known to us. All 16 mutant alleles were identified, but only five different mutations, all with a severe impact on the protein, were found; these five mutations were as follows: two nonsense mutations (E20X and E118X), a 1-bp deletion (27delG), a splice mutation (IVS2+5G-->A), and a missense mutation (S67P) resulting in reduced amounts of abnormal HE1 protein. E20X, with an overall allele frequency of 56%, was established as the common mutant allele. Prenatal diagnosis was achieved by mutation analysis of an uncultured chorionic-villus sample. All mutations except 27delG were observed in a homozygous state, allowing genotype/phenotype correlations. In seven families (with E20X, E118X, S67P, and E20X/27delG mutations), patients suffered a severe and rapid disease course, with age at death being 6 mo-4 years. A remarkable feature was the pronounced lung involvement, leading, in six patients, to early death caused by respiratory failure. Two patients also developed a severe neurological disease with onset during infancy. Conversely, the splice mutation corresponded to a very different clinical presentation, with juvenile onset of neurological symptoms and prolonged survival. This mutation generated multiple transcripts, including a minute proportion of normally spliced RNA, which may explain the milder phenotype.

Follow-up study of subunit c of mitochondrial ATP synthase (SCMAS) in Batten disease and in unrelated lysosomal disorders

Abstract Immunohistochemical and biochemical studies of subunit c of mitochondrial ATP synthase (SCMAS) storage were carried out in neuronal ceroid lipofuscinosis (NCL) and in a series of unrelated inherited and acquired lysosomal disorders. In the NCL group, represented by the late infantile, early juvenile and juvenile types, SCMAS storage was generalized neurovisceral, with considerable difference in the visceral storage pattern between the types. In late infantile NCL the SCMAS storage was intensive and corresponded to the generalized, autofluorescent, uniformly curvilinear material, irrespective of the cell type affected. In both early juvenile and juvenile NCLs the SCMAS storage was strong and almost uniform in brain neurons, but did not correlate entirely with the visceral autofluorescent storage pool, being undetectable in autofluorescent storage deposits in a constant set of tissues. In the adult (Kufs) type, the brain neurons were stained with various intensity. In infantile NCL, SCMAS storage was restricted to some of the persisting neurons. In a series of inherited lysosomal enzymopathies and acquired lysosomal disorders, excessive SCMAS accumulation was found only in secondary neuronal lipopigments. It occurred as an early and more uniform phenomenon in mucopolysaccharidosis types I, II, IIIA and in polysulphatase deficiency, or as a delayed varied phenomeno in protracted variants of mucolipidosis I, Niemann-Pick types A and C, and GM2 and GM1 gangliosidoses. Neuronal ageing led to an irregular increase in immunodetectable SCMAS epitope in some neuronal lipofuscin granules. There was no evidence of significant SCMAS lysosomal accumulation in non-neural cells in the whole group, regardless of whether lipofuscin or ceroid accumulation occurred or not. The neuronal SCMAS storage is thus nosologically a common unspecific phenomenon, which is especially amplified in NCL. The specificity of the NCL storage process is shown by the fact that even lysosomes of non-neuronal cells in NCL accumulate SCMAS.

Cardiac manifestations in Fabry disease.

Fabry disease is an X-linked recessive genetic disorder of glycosphingolipid metabolism, due to deficiency of the lysosomal enzymeα-galactosidase A. The disease is characterized by the progressive intracellular lysosomal accumulation of neutral glycosphingolipids throughout the body, including the cardiovascular system.It has been reported that cardiac involvement could be the sole manifestation of the disease in some patients. Myocardial abnormalities are characterized mainly by left ventricular (LV) wall thickening without significant cavity dilatation, the most frequent abnormal structural pattern being concentric LV hypertrophy (LVH). In some patients the disease mimics a typical hypertrophic obstructive cardiomyopathy. According to our experience, systolic function is largely preserved in a large majority of affected individuals. In contrast, mild to moderate impairment of diastolic filling is a relatively common finding, representing probably the most important cause of dyspnoea in patients with Fabry disease. However, in a relatively large population of affected patients, severe diastolic dysfunction, typical of restrictive cardiomyopathy, was not found. Valvular structural abnormalities are frequent due to valvular infiltration. In several patients, hypertrophy of papillary muscles and/or systolic anterior motion of the mitral leaflets associated with LV outflow obstruction may aggravate the mitral valve dysfunction. We did not confirm the previously reported high prevalence of mitral valve prolapse. Valvular regurgitation seems to be relatively frequent but mostly non-significant. Electrocardiographic changes in Fabry disease are multiple and include at rioventricular (AV) conduction abnormalities (abbreviation of the P-R interval or AV blocks), signs of LVH and repolarization abnormalities. Our observations suggest that conduction defects and repolarization changes are present predominantly in subjects with LV structural abnormalities. Cardiac symptoms inpatients with Fabry disease include shortness of breath on effort (related to LV diastolic dysfunction), vasospastic and/or exertional angina pectoris (due to LVH, endothelial dysfunction and/or fixed coronary artery stenosis) and syncope (related to AV blocks or LV outflow obstruction). The extent of cardiac involvement, in particular LV mass assessment, could represent an ideal surrogate endpoint for evaluating the efficacy of specific therapies.

Relationship between X-inactivation and clinical involvement in Fabry heterozygotes. Eleven novel mutations in the α-galactosidase A gene in the Czech and Slovak population

We have identified 21 different α-galactosidase A gene (GLA) mutations in 22 unrelated Czech and Slovak families with Fabry disease. Eleven of these mutations were novel (point mutations D93N, A135V, D155H, G171R, Q280K, G360S, Q330X, splicing errors c.194ins14, c.801ins36 and deletions c.674_732del59, g.3405_6021del2617). Genotyping of family members for family-specific mutations revealed 55 heterozygotes that manifested clinical symptoms of different severity. To examine the contribution of X-inactivation skewing to disease manifestation in Fabry heterozygotes, we have adopted the Mainz severity scoring scheme and compared the score values with the X-inactivation status in 39 carriers in an age-dependent manner. The age-score trendline of Fabry females who had a predominantly inactivated X-chromosome bearing a wild-type GLA allele (10 of 38 females) was markedly steeper than in the rest of the cohort. One female carrier with an inactivated mutated allele had a low score value when compared to the other heterozygotes of the same age. These data suggest that X-inactivation is indeed a major factor determining the severity of clinical involvement in Fabry heterozygotes. There was a statistically significant difference between the severity score values of heterozygotes with random and non-random X-chromosome inactivation at the 5% level of significance. Further studies will show if the degree of the wildtype allele inactivation will be useful as a predictive marker of severity of phenotype in Fabry heterozygotes. Although the correlation between X-inactivation skewing and presentation of the disease in Fabry heterozygotes has previously been suggested in the literature, this report is among the first attempts to examine this relationship systematically.

Dominant Renin Gene Mutations Associated with Early-Onset Hyperuricemia, Anemia, and Chronic Kidney Failure

Through linkage analysis and candidate gene sequencing, we identified three unrelated families with the autosomal-dominant inheritance of early onset anemia, hypouricosuric hyperuricemia, progressive kidney failure, and mutations resulting either in the deletion (p.Leu16del) or the amino acid exchange (p.Leu16Arg) of a single leucine residue in the signal sequence of renin. Both mutations decrease signal sequence hydrophobicity and are predicted by bioinformatic analyses to damage targeting and cotranslational translocation of preprorenin into the endoplasmic reticulum (ER). Transfection and in vitro studies confirmed that both mutations affect ER translocation and processing of nascent preprorenin, resulting either in reduced (p.Leu16del) or abolished (p.Leu16Arg) prorenin and renin biosynthesis and secretion. Expression of renin and other components of the renin-angiotensin system was decreased accordingly in kidney biopsy specimens from affected individuals. Cells stably expressing the p.Leu16del protein showed activated ER stress, unfolded protein response, and reduced growth rate. It is likely that expression of the mutant proteins has a dominant toxic effect gradually reducing the viability of renin-expressing cells. This alters the intrarenal renin-angiotensin system and the juxtaglomerular apparatus functionality and leads to nephron dropout and progressive kidney failure. Our findings provide insight into the functionality of renin-angiotensin system and stress the importance of renin analysis in families and individuals with early onset hyperuricemia, anemia, and progressive kidney failure.

Subclinical course of cholesteryl ester storage disease in an adult with hypercholesterolemia, accelerated atherosclerosis, and liver cancer

Few cases of asymptomatic cholesteryl ester storage disease (CESD) due to low enzymatic activity of human lysosomal acid lipase/cholesteryl ester hydrolase (hLAL) have been reported thus far in adults Here, we describe a 51-year-old man with a long clinical history of mixed hyperlipoproteinemia and severe premature atherosclerosis, but with no signs of hepatomegaly, liver dysfunction, or splenomegaly. The disease was discovered by chance in a biopsy performed because of suspected liver cancer (proven to be a cholangiocarcinoma). Residual hLAL activity in peripheral leukocytes was determined to be 6% of control values. DNA sequence and restriction fragment length polymorphism analysis demonstrated that the patient was a compound heterozygote for the prevalent CESD exon 8 splice site mutation (G934A) and the deletion of a C (nucleotide 673, 674, or 675) in exon 6 of the hLAL gene, resulting in premature termination of protein translation at residue 195. The patient died of liver failure as a consequence of extensive tumor infiltration at age 52. Lipid analysis revealed moderate cholesteryl ester storage in the liver and in the suprarenal cortex, and massive accumulation in the testicular histiocytes and Leydig cells, resulting in a pronounced secondary atrophy of the seminiferous tubules. Our case study demonstrates that hepatomegaly is an inconstant feature, even in CESD patients compound heterozygous for a Wolman mutation which results in complete loss of hLAL enzymic activity. It also highlights the need to be aware of this condition as it may be underdiagnosed.

Mutations in CLN7/MFSD8 are a common cause of variant late-infantile neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs), the most common neurodegenerative disorders of childhood, are characterized by the accumulation of autofluorescent storage material mainly in neurons. Although clinically rather uniform, variant late-infantile onset NCL (vLINCL) is genetically heterogeneous with four major underlying genes identified so far. We evaluated the genetic background underlying vLINCL in 119 patients, and specifically analysed the recently reported CLN7/MFSD8 gene for mutations in 80 patients. Clinical data were collected from the CLN7/MFSD8 mutation positive patients. Eight novel CLN7/MFSD8 mutations and seven novel mutations in the CLN1/PPT1, CLN2/TPP1, CLN5, CLN6 and CLN8 genes were identified in patients of various ethnic origins. A significant group of Roma patients originating from the former Czechoslovakia was shown to bear the c.881C>A (p.Thr294Lys) mutation in CLN7/MFSD8, possibly due to a founder effect. With one exception, the CLN7/MFSD8 mutation positive patients present a phenotype indistinguishable from the other vLINCL forms. In one patient with an in-frame amino acid substitution mutation in CLN7/MFSD8, the disease onset was later and the disease course less aggressive than in variant late-infantile NCL. Our findings raise the total number of CLN7/MFSD8 mutations to 14 with the majority of families having private mutations. Our study confirms that CLN7/MFSD8 defects are not restricted to the Turkish population, as initially anticipated, but are a relatively common cause of NCL in different populations. CLN7/MFSD8 should be considered a diagnostic alternative not only in variant late-infantile but also later onset NCL forms with a more protracted disease course. A significant number of NCL patients in Turkey exist, in which the underlying genetic defect remains to be determined.

Frontal lobe atrophy due to a mutation in the cholesterol binding protein HE1/NPC2

This is the first description of slowly progressive Niemann–Pick disease type C (NPC) without the typical lysosomal storage in bone marrow and viscera in two descendants of a group of 17th century French‐Canadians. The index patient was a married 43‐year‐old woman with onset of dementia in her thirties, later followed by the development of ataxia and athetoid movements. Her autopsy disclosed frontal lobe atrophy, neurolysosomal storage with oligolamellar inclusion and tau‐positive neurofibrillary tangles. Of the 119 family members screened, only a married 42‐year‐old sister displayed symptoms of a dementia. Both women displayed vertical supranuclear ophthalmoplegia; expressive aphasia; concrete, stimulus‐bound, perseverative behavior; and impaired conceptualization and planning. Cultured fibroblasts showed decreased cholesterol esterification and positive filipin staining, but no mutation was detected in coding or promoter regions of the NPC1 gene using conformation sensitive gel electrophoresis and sequencing. Sequencing showed a homozygous gene mutation that is predicted to result in an amino acid substitution, V39M, in the cholesterol binding protein HE1 (NPC2). Adult‐onset NPC2 with lysosomal storage virtually restricted to neurons represents a novel phenotypic and genotypic variant with diffuse cognitive impairment and focal frontal involvement described for the first time. Ann Neurol 2002;52:000–000

Niemann-Pick disease

The results of a complex analysis of liver tissue are presented (four biopsy and two autopsy samples) obtained from six patients with Niemann-Pick disease (NPD) with a gross deficiency of sphingomyelinase (SMase) accompanied by a typical increase in sphingomyelin (SM). There were five cases of NPD type A (four of them with an atypical, prolonged course) and one case of type B. By means of lipid histochemistry it was possible to demonstrate SM storage both in hepatocytes and in the reticuloendothelial system (RES) of the liver (Kupffer cells and portal macrophages) and to show in two siblings with NPD type A a so-far undescribed centrilobular storage pattern. Enzyme histochemistry revealed a secondary deficit of nonspecific esterase activity and acid β-galactosidase in liver storage macrophages and varying degrees of suppression of hepatocytic enzyme activities as a reaction to lipid storage of sudden onset. Ultrastructurally, it was possible to demonstrate cholesterol in lysosomes by using digitonin fixation, the involvement of Ito cells in lipid storage, the aggregation of storage lysosomes with certain other organelles and their occasional connections with the endoplasmic reticulum. The problems of possible lipid extraction during processing were considered as a cause of pronounced lysosomal electron-lucidity and of the ultrastructural identification of the participating lipopigment. The significance of the findings is discussed in relation to the existing classification and, particularly, to the stored lipid dilemma of cases of NPD type C.