Novel homozygous and compound heterozygous mutations of sterol 27-hydroxylase gene (CYP27) cause cerebrotendinous xanthomatosis in three Japanese patients from two unrelated families

A double CYP27A1 gene mutation in spinal cerebrotendinous xanthomatosis in a patient presenting with spastic gait: a case report

BACKGROUND

Cerebrotendinous xanthomatosis (CTX, OMIM #213700) is a rare inherited metabolic disease caused by the mutation in the CYP27A1 gene. Spinal CTX is a rare clinical subgroup of CTX which lacks typical symptoms seen in classical CTX. Here we report a spinal CTX case revealed double mutation of CYP27A1 gene.

CASE PRESENTATION

A 42-year-old Asian man visited our hospital with spastic gait started at 35. Physical examination showed bilateral masses on his Achilles tendons and were identified as xanthoma on ankle magnetic resonance imaging (MRI). Brain and spinal cord MRI revealed high signal lesions in bilateral cerebellar dentate nuclei and long tract lesions involving lateral corticospinal and gracile tracts. Gene analysis revealed double heterozygous mutation, c.223C > T (p. Gln75Ter) and c.1214G > A (p. Arg405Gln).

CONCLUSIONS

We believe that novel mutation detected in our case might have a role in the pathomechanism in CTX. Moreover, spinal CTX should be considered in the patients only presenting with pyramidal symptoms, as CTX shows good prognosis in early treatment with chenodeoxycholic acid.

Genetic origin of patients having spastic paraplegia with or without other neurologic manifestations

Background

Hereditary spastic paraplegia (HSP) is a group of neurodegenerative diseases characterized by lower-limb spastic paraplegia with highly genetic and clinical heterogeneity. However, the clinical sign of spastic paraplegia can also be seen in a variety of hereditary neurologic diseases with bilateral corticospinal tract impairment. The purpose of this study is to identify the disease spectrum of spastic paraplegia, and to broaden the coverage of genetic testing and recognize clinical, laboratorial, electrophysiological and radiological characteristics to increase the positive rate of diagnosis.

Methods

Twenty-seven cases were screened out to have definite or suspected pathogenic variants from clinically suspected HSP pedigrees through HSP-associated sequencing and/or expanded genetic testing. One case was performed for enzyme detection of leukodystrophy without next-generation sequencing. In addition, detailed clinical, laboratorial, electrophysiological and radiological characteristics of the 28 patients were presented.

Results

A total of five types of hereditary neurological disorders were identified in 28 patients, including HSP (15/28), leukodystrophy (5/28), hereditary ataxia (2/28), methylmalonic acidemia/methylenetetrahydrofolate reductase deficiency (5/28), and Charcot-Marie-tooth atrophy (1/28). Patients in the HSP group had chronic courses, most of whom were lower limbs spasticity, mainly with axonal neuropathy, and thinning corpus callosum, white matter lesions and cerebellar atrophy in brain MRI. In the non-HSP groups, upper and lower limbs both involvement was more common. Patients with homocysteine remethylation disorders or Krabbe’s disease or autosomal recessive spastic ataxia of Charlevoix-Saguenay had diagnostic results in laboratory or imaging examination. A total of 12 new variants were obtained.

Conclusions

HSP had widespread clinical and genetic heterogeneity, and leukodystrophy, hereditary ataxia, Charcot-Marie-Tooth atrophy and homocysteine remethylation disorders accounted for a significant proportion of the proposed HSP. These diseases had different characteristics in clinical, laboratorial, electrophysiological, and radiological aspects, which could help differential diagnosis. Genetic analysis could ultimately provide a clear diagnosis, and broadening the scope of genetic testing could improve the positive rate of diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02708-z.

A Late-onset and Relatively Rapidly Progressive Case of Pure Spinal Form Cerebrotendinous Xanthomatosis with a Novel Mutation in the CYP27A1 Gene

A 61-year-old Japanese man with the pure spinal form of cerebrotendinous xanthomatosis developed dysesthesia of the lower limbs and gait disturbance at 57 years of age. At 61 years old, he was unable to walk without support. A neurological examination showed spasticity and sensory disturbance in the lower limbs. Spinal MRI showed long hyperintense lesions involving the lateral and posterior funiculus in the cervical and thoracic cord on T2-weighted images. His serum cholestanol level was markedly elevated. A CYP27A1 gene analysis identified two missense variants, p.R474W, and a novel p.R262C variant. Combination therapy with chenodeoxycholic acid and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase decreased his serum cholestanol level.

Nationwide survey on cerebrotendinous xanthomatosis in Japan

Cerebrotendinous xanthomatosis (CTX) is likely to be underdiagnosed and precise epidemiological characteristics of CTX are largely unknown as knowledge on the disorder is based mainly on case reports. We conducted a nationwide survey on CTX to elucidate the frequency, clinical picture, and molecular biological background of Japanese CTX patients. In this first Japanese nationwide survey on CTX, 2541 questionnaires were sent to clinical departments across Japan. A total of 1032 (40.6%) responses were returned completed for further analysis. Forty patients with CTX (50.0% male) were identified between September 2012 and August 2015. The mean age of onset was 24.5 ± 13.6 years, mean age at diagnosis was 41.0 ± 11.6 years, and corresponding mean duration of illness from onset to diagnosis was 16.5 ± 13.5 years. The most common initial symptom was tendon xanthoma, followed next by spastic paraplegia, cognitive dysfunction, cataract, ataxia, and epilepsy. The most predominant mutations in the CYP27A1 gene were c.1214G> A (p.R405Q, 31.6%), c.1421G> A (p.R474Q, 26.3%), and c.435G> T (p.G145=, 15.8%). Therapeutic interventions that included chenodeoxycholic acid, HMG-CoA reductase inhibitor, and LDL apheresis reduced serum cholestanol level in all patients and improved clinical symptoms in 40.5% of patients. Although CTX is a treatable neurodegenerative disorder, our nationwide survey revealed an average 16.5-year diagnostic delay. CTX may be underdiagnosed in Japan, especially during childhood. Early diagnosis and treatment are essential to improve the prognosis of CTX.

Spinal form cerebrotendinous xanthomatosis patient with long spinal cord lesion

CONTEXT

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessively inherited lipid storage disease caused by mutation in the CYP27A1 gene. Spinal form CTX is a rare clinical subgroup of CTX and only 14 patients from 11 families have been reported to date. Here, we report the first Asian patient with spinal form CTX showing characteristic radiological findings.

FINDINGS

The patient, a 46-year-old Japanese male, developed sensory disturbance of the lower legs at 39 and spastic gait at 46 years of age. Spinal cord magnetic resonance imaging (MRI) revealed a long hyperintense lesion involving lateral corticospinal tracts and gracile tracts in the cervical and thoracic cord on T2-weighted images. Gallium-67 (⁶⁷Ga) scintigraphy revealed abnormal uptake in the Achilles tendons and the serum cholestanol level was elevated. CYP27A1 gene analysis identified homozygous missense mutation, c.1214G>A (p.R405Q). The patient was treated with atorvastatin monotherapy, which reduced serum cholestanol to less than 50% of the pretreatment level.

CONCLUSION

Spinal form CTX should be considered in the differential diagnosis of cryptogenic myelopathy, especially in patients with a long spinal cord lesion, as treatment with chenodeoxycholic acid and/or competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase reverse the metabolic derangement and prevent the neurologiccal dysfunction.

Clinical and radiological findings of a cerebrotendinous xanthomatosis patient with a novel p.A335V mutation in the CYP27A1 gene

We herein describe the case of a Japanese cerebrotendinous xanthomatosis (CTX) patient with a novel CYP27A1 gene mutation. The patient had been diagnosed with cataracts at 25 years of age and subsequently developed neurological symptoms in his forties, being referred to our hospital at 47 years of age. Upon admission, Achilles tendon xanthomas, cognitive impairment, dysphagia, dysarthria, dystonia, spasticity, muscle weakness and ataxia were observed. Brain MRI revealed abnormal signals in the dentate nuclei, periventricular white matter and pyramidal tract, and the serum cholestanol level was elevated. A CYP27A1 gene analysis identified compound heterozygosity for p.A335V, a novel mutation, and p.R405Q, a previously reported mutation. Making an early diagnosis of CTX is crucial, as the administration of chenodeoxycholic acid reverses metabolic derangement.

Three siblings with Cerebrotendinous Xanthomatosis: a novel mutation in the CYP27A1 gene

Cerebrotendinous Xanthomatosis (CTX) is a rare autosomal recessive lipid storage disease caused by sterol 27-hydroxylase (CYP27) deficiency. We report three CTX siblings that shared a novel mutation of the CYP27A1 gene. These siblings presented with elevated cholestanol levels and typical manifestations such as tendon xanthomas, cataracts, osteopenia, mental retardation, cerebellar ataxia and peripheral neuropathy. All shared the same genetic mutation, c.1146_1151delins and c.1214G>A of CYP27A1. All were treated with 750 mg/day chenodeoxycholic acid (CDCA). In conclusion, one should consider the possibility of CTX in any individual with normocholesterolemic xanthomatosis, early-onset cataracts, mental retardation, cerebellar ataxia and peripheral neuropathy.

A novel mutation in the sterol 27-hydroxylase gene of a woman with autosomal recessive cerebrotendinous xanthomatosis

Article abstract

Mutations of the gene encoding the mitochondrial enzyme sterol 27-hydroxylase (CYP27A1 gene) cause defects in the cholesterol pathway to bile acids that lead to the storage of cholestanol and cholesterol in tendons, lenses and the central nervous system. This disorder is the cause of a clinical syndrome known as cerebrotendinous xanthomatosis (CTX). Since 1991 several mutations of the CYP27A1 gene have been reported. We diagnosed the clinical features of CTX in a caucasian woman. Serum levels of cholestanol and 7α-hydroxycholesterol were elevated and the concentration of 27-hydroxycholesterol was reduced. Bile alcohols in the urine and faeces were increased. The analysis of the CYP27A1 gene showed that the patient was a compound heterozygote carrying two mutations both located in exon 8. One mutation is a novel four nucleotide deletion (c.1330-1333delTTCC) that results in a frameshift and the occurrence of a premature stop codon leading to the formation of a truncated protein of 448 amino acids. The other mutation, previously reported, is a C - > T transition (c. c.1381C > T) that converts the glutamine codon at position 461 into a termination codon (p.Q461X). These truncated proteins are expected to have no biological function being devoid of the cysteine residue at position 476 of the normal enzyme that is crucial for heme binding and enzyme activity.

Identification of a novel missense mutation in the sterol 27-hydroxylase gene in two Japanese patients with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive sterol storage disease caused by a mutated sterol 27-hydroxylase (CYP27A1) gene. We analyzed the CYP27A1 gene in two Japanese CTX patients. The CYP27A1 gene was amplified by PCR and screened by PCR-SSCP. The nucleotide sequence was analyzed to confirm mutations. Case 1 was a compound heterozygote for Arg104Gln in exon 2 and Arg441Gln in exon 8. To our knowledge, this is the first report in which the Arg104Gln mutation is identified in CTX patients. Probably case 2 would be a compound heterozygote for Arg441Trp in exon 8 and a mutation that was not identified.

Expression profiles of phases 1 and 2 metabolizing enzymes in human skin and the reconstructed skin models Episkin and full thickness model from Episkin

BACKGROUND

Episkin and full thickness model from Episkin (FTM) are human skin models obtained from in vitro growth of keratinocytes into the five typical layers of the epidermis. FTM is a full thickness reconstructed skin model that also contains fibroblasts seeded in a collagen matrix.

OBJECTIVES

To assess whether enzymes involved in chemical detoxification are expressed in Episkin and FTM and how their levels compare with the human epidermis, dermis and total skin.

METHODS

Quantification of the mRNA expression levels of phases 1 and 2 metabolizing enzymes in cultured Episkin and FTM and human epidermis, dermis and total skin using Realtime PCR.

RESULTS

The data show that the expression profiles of 61 phases 1 and 2 metabolizing enzymes in Episkin, FTM and epidermis are generally similar, with some exceptions. Cytochrome P450-dependent enzymes and flavin monooxygenases are expressed at low levels, while phase 2 metabolizing enzymes are expressed at much higher levels, especially, glutathione-S-transferase P1 (GSTP1) catechol-O-methyl transferase (COMT), steroid sulfotransferase (SULT2B1b), and N-acetyl transferase (NAT5). The present study also identifies the presence of many enzymes involved in cholesterol, arachidonic acid, leukotriene, prostaglandin, eicosatrienoic acids, and vitamin D3 metabolisms.

CONCLUSION

The present data strongly suggest that Episkin and FTM represent reliable and valuable in vitro human skin models for studying the function of phases 1 and 2 metabolizing enzymes in xenobiotic metabolisms. They could be used to replace invasive methods or laboratory animals for skin experiments.

Cerebrotendinous xanthomatosis: a critical update

Cerebrotendinous xanthomatosis (CTX) also known as van Bogaert–Scherer–Epstein syndrome, Thiebaut’s syndrome and cerebrotendinous cholesterosis, is an autosomal-recessive lipid-storage disease characterized by the triad of juvenile cataracts, tendon xanthomas and progressive neurodegeneration. Excess cholesterol and cholestanol are deposited in multiple organs, including the cerebrum, cerebellum, lens and tendons. Approximately 300 cases are reported worldwide, but it is suspected that the incidence of CTX is underestimated. The disease is attributed to approximately 50 mutations in the CYP27A1 gene coding for the enzyme sterol 27-hydoxylase, which is responsible for initial oxidation of the side chain of the cholesterol molecule in bile acid biosynthesis. CTX has varied clinical presentations, but no genotype–phenotype relationship has been documented. In some intrafamilial cases, clinical presentations may vary considerably. MRI for CTX is sensitive for diagnosis and classically demonstrates cerebral and cerebellar atrophy and xanthomatous lesions preferentially affecting the dentate nuclei. Patients have high serum levels of cholestanol with normal total cholesterol and increased urinary excretion of bile acids. Treatment of patients with chenodeoxycholic acid, particularly when used along with HMG-CoA reductase inhibitors (statins) or low-density lipoprotein apheresis, can normalize cholestanol levels as well as prevent further degeneration. Therefore, the need for early diagnosis is well documented in the literature, as it prevents the significant morbidity and mortality associated with this disease.

Mutational analysis of CYP27A1: assessment of 27-hydroxylation of cholesterol and 25-hydroxylation of vitamin D

The CYP27A1 gene encodes a mitochondrial enzyme that modulates the acidic biosynthetic pathway for bile acids beginning with the 27-hydroxylation of cholesterol. CYP27A1 also 25-hydroxylates vitamin D(3). Gene mutations cause cerebrotendinous xanthomatosis (CTX), an autosomal recessive disorder, and may cause 25-hydroxyvitamin D deficiency and early-onset osteoporosis and fractures in affected patients. To examine the effects of mutations of CYP27A1 on vitamin D and cholesterol hydroxylating activity, recombinant CYP27A1 and mutant complementary DNAs produced by site-directed mutagenesis were stably expressed in either Escherichia coli or COS-1 cells. Activities of wild-type and mutant enzymes were determined with cholesterol, vitamin D(3), and 1alpha-hydroxyvitamin D(3) (1alphaOHD(3)) as substrates. Of the 15 mutants tested, 11 expressed protein and 4 expressed little or no protein. Functional heme activity, estimated by reduced CO difference spectra at 450 nm, was absent in 12 mutants. When expressed in E. coli, 3 mutants, K226R, D321G, and P408S, each known to cause clinically CTX, showed modest decreases in reduced CO spectra peak and either no change or decreases of less than 50% in hydroxylation of cholesterol, vitamin D(3), and 1alphaOHD(3) compared with wild type. When expressed transiently in COS-1 cells, each of these mutants showed 25-hydroxylation activity for 1alphaOHD(3) as well as wild type. Thus, 3 mutants, K226R, D321G, and P408S, known to occur clinically with nonfunctioning mutants, hydroxylated cholesterol, vitamin D(3), and 1alphaOHD(3). How they contribute to the pathogenesis of CTX despite being biologically active in vitro remains to be determined.

Defects in bile acid biosynthesis--diagnosis and treatment

Bile acid synthetic defects represent a specific category of metabolic liver disease. This article highlights the history and summarizes our analytical approach to the diagnosis and treatment of genetic defects in bile acid synthesis. By the application of mass spectrometry as a screening tool, it is possible to perform rapid diagnosis of potential inborn errors in bile acid synthesis from urinary bile acid analysis. Molecular techniques then afford the identification of specific mutations in genes encoding the enzymes responsible for bile acid synthesis. Using this approach, 6 of the 7 known genetic defects that are causes of progressive cholestatic liver disease, syndromes of fat-soluble vitamin malabsorption, or neurological disease, have been characterized. Bile-acid therapy using oral cholic acid has proven effective in most of these bile acid synthetic defects making early diagnosis crucial to optimum clinical prognosis.

New insights into the pathological mechanisms of cerebrotendinous xanthomatosis in the Taiwanese using genomic and proteomic tools

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid-storage disorder caused by a deficiency of the mitochondrial sterol 27-hydroxylase. Genetic analysis utilizing SSCP and direct DNA sequencing identified a new mutation. One base-pair of cytosine was deleted at codon 326 on exon 2 of CYP27 in all CTX patients while their father was heterozygotic. This novel point deletion predicts a frameshift in mRNA (Pro(102) -->Leu) and results in the appearance of a premature termination codon (TGA) to substitute for Val(106) (GTG). To characterize the pathological mechanism of CTX patients, the protein profiles of serum and leukocytes extracted from these subjects were presented by means of proteomic technologies including 2-DE and MALDI-TOF analysis. According to the results, the amount of vinculin, ABP-280, talin and vimentin in leukocytes of CTX patients had changed significantly, reflecting the changes in membrane dynamics concerning cholestanol accumulation. The expression of target proteins in CTX patients and control was further verified by western blotting which indicated the same tendency as 2-DE data. This is the first paper to integrate both genomic and proteomic concepts for analyzing the possible mechanism of CTX and provides more information for related study in the future.

Cerebrotendinous xanthomatosis in a Hong Kong Chinese kinship with a novel splicing site mutation IVS6-1G>T in the sterol 27-hydroxylase gene

We reported a Hong Kong Chinese proband with Cerebrotendinous Xanthomatosis in which a novel acceptor splicing site mutation (IVS6-1G>T) was identified. Family screening revealed the same mutation in his elder brother and the youngest sister. All the three affected siblings were compound heterozygous for IVS6-1G>T and a known missense mutation R372Q (GenBank Accession No. M62401). Significant phenotypic variation was noted among them that the youngest sister was still symptom-free at the time of writing.

Cholestanol Metabolism, Molecular Pathology, and Nutritional Implications

Cholestanol, not cholesterol, is a minor component in the human body and in foods, but an increase in cholestanol concentration in serum induces a pathological condition named cerebrotendinous xanthomatosis (CTX). In our investigation of this disease for more than 25 years, a procedure for quantification of cholestanol by high-performance liquid chromatography and an assay method for sterol 27-hydroxylase were established, and several mutations of the CYP 27 gene in 10 CTX families were identified. We also established experimental animal models with symptoms of CTX by feeding a high cholestanol diet. Corneal dystrophy and gallstones were produced in mice, and an apoptosis of cerebellar neuronal cells was observed in rats. We propose the following underlying mechanism of CTX pathogenesis: When cholesterol in the plasma membrane is replaced by cholestanol to some extent, the membrane fluidity is reduced, and the calcium channel fails to open, inducing cell death. CTX patients are treated with oral administration of chenodeoxycholic acid, which reduces the cholestanol concentration in serum. Cholestanol has a toxic effect, and an imbalance of the cholesterol/cholestanol ratio in plasma membrane is suspected to cause the disturbance of calcium channel function of the membrane.

Cerebrotendinous xanthomatosis: molecular characterization of two Scandinavian sisters

Cerebrotendinous xanthomatosis (CTX) is a hereditary disorder, which is inherited as an autosomally recessive disease, causing production of cholesterol and cholestanol xanthomas and mental retardation. The disease is caused by mutations in the gene for sterol 27-hydroxylase (CYP27A1). The only CTX patients diagnosed in Scandinavia are two Norwegian sisters from a consanguineous marriage. Here we have characterized the mutation and its functional consequences for the enzyme. Analysis of genomic DNA from cultured fibroblasts identified a base exchange C > T in position 1441, causing arginine at amino acid position 441 to be replaced by tryptophan. The same mutation was introduced by mutagenesis in the complimentary DNA (cDNA) for CYP27, ligated into the expression vector pcDNA4/HisMax and transfected into HEK293 cells. The mutated enzyme had less than 5% of the enzyme activity compared with the native enzyme. No abnormal catalytic products could be identified in the cell culture medium. Probably the mutation affects the haem binding within the holoenzyme. The mutation has also previously been reported in a Japanese family. This is the second example of a CTX-causing mutation that has been recognized in more than one population.

Frontal lobe dementia with abnormal cholesterol metabolism and heterozygous mutation in sterol 27-hydroxylase gene (CYP27)

Of the primary dementing disorders that cause frontotemporal dementia, the best-known is Pick disease. We report on a 44-year-old woman with progressive frontal lobe dementia and spastic paraplegia. Examination revealed increased serum levels of cholestanol with abnormal cholesterol metabolism and a heterozygous mutation of the sterol 27-hydroxylase gene (CYP27). Biochemical findings were compatible with cerebrotendinous xanthomatosis (CTX); however, the clinical manifestations were very dissimilar. To our knowledge, a symptomatic carrier of this mutation among CTX patients has not been reported. We speculate that the present patient has a previously undescribed neurodegenerative disease related to abnormal cholesterol metabolism with this heterozygous mutation.

Clinical and molecular genetic characteristics of patients with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease caused by a deficiency of the mitochondrial enzyme 27-sterol hydroxylase (CYP 27), due to mutations in its gene. In this study we report on mutations in 58 patients with CTX out of 32 unrelated families. Eight of these were novel mutations, two of which were found together with two already known pathogenic mutations. Twelve mutations found in this patient group have been described in the literature. In the patients from 31 families, mutations were found in both alleles. In the literature, 28 mutations in 67 patients with CTX out of 44 families have been described. Pooling our patient group and the patients from the literature together, 37 different mutations in 125 patients out of 74 families were obtained. Identical mutations have been found in families from different ethnic backgrounds. In 41% of all the patients, CYP 27 gene mutations are found in the region of exons 6-8. This region encodes for adrenodoxin and haem binding sites of the protein. Of these 125 patients, a genotype-phenotype analysis was done for 79 homozygous patients harbouring 23 different mutations, out of 45 families. The patients with compound heterozygous mutations were left out of the genotype-phenotype analysis. The genotype-phenotype analysis did not reveal any correlation.

Oxysterols: modulators of cholesterol metabolism and other processes

Oxygenated derivatives of cholesterol (oxysterols) present a remarkably diverse profile of biological activities, including effects on sphingolipid metabolism, platelet aggregation, apoptosis, and protein prenylation. The most notable oxysterol activities center around the regulation of cholesterol homeostasis, which appears to be controlled in part by a complex series of interactions of oxysterol ligands with various receptors, such as the oxysterol binding protein, the cellular nucleic acid binding protein, the sterol regulatory element binding protein, the LXR nuclear orphan receptors, and the low-density lipoprotein receptor. Identification of the endogenous oxysterol ligands and elucidation of their enzymatic origins are topics of active investigation. Except for 24, 25-epoxysterols, most oxysterols arise from cholesterol by autoxidation or by specific microsomal or mitochondrial oxidations, usually involving cytochrome P-450 species. Oxysterols are variously metabolized to esters, bile acids, steroid hormones, cholesterol, or other sterols through pathways that may differ according to the type of cell and mode of experimentation (in vitro, in vivo, cell culture). Reliable measurements of oxysterol levels and activities are hampered by low physiological concentrations (approximately 0.01-0.1 microM plasma) relative to cholesterol (approximately 5,000 microM) and by the susceptibility of cholesterol to autoxidation, which produces artifactual oxysterols that may also have potent activities. Reports describing the occurrence and levels of oxysterols in plasma, low-density lipoproteins, various tissues, and food products include many unrealistic data resulting from inattention to autoxidation and to limitations of the analytical methodology. Because of the widespread lack of appreciation for the technical difficulties involved in oxysterol research, a rigorous evaluation of the chromatographic and spectroscopic methods used in the isolation, characterization, and quantitation of oxysterols has been included. This review comprises a detailed and critical assessment of current knowledge regarding the formation, occurrence, metabolism, regulatory properties, and other activities of oxysterols in mammalian systems.

Cholestanol induces apoptosis of cerebellar neuronal cells

Cerebrotendinous xanthomatosis (CTX) is a hereditary lipid storage disease characterized by hyper-cholestanolemia, cerebellar ataxia, xanthoma, and cataract. We hypothesized that cholestanol in serum of CTX patients might induce neuronal cell death in the cerebellum and eventually lead to cerebellar ataxia. To gain support for this hypothesis we developed hyper-cholestanolemia rats by feeding cholestanol. Neuronal cells, especially Purkinje cells in the cerebellum were stained by Sudan black B only in the cholestanol-fed rats, indicating the deposit of cholestanol in cerebellum. To examine effects of cholestanol in vitro, cerebellar neuronal cells were cultured with cholestanol. The cholestanol concentration increased and the viability decreased in cells cultured with cholestanol. Apoptosis was evident in cells cultured with cholestanol more frequently than in control cells, determined using the terminal deoxynucleotidyl transferase (TdT) dUTP nick end-labeling (TUNEL) method. As activities of interleukin-1beta-converting enzyme (ICE) and CPP32 protease were increased in cells cultured with cholestanol, all these data taken together suggest that cholestanol induced apoptosis of cerebellar neuronal cells. Our observations may explain the mechanism of cerebellar ataxia of CTX patients.