Clinical and molecular genetic characteristics of patients with cerebrotendinous xanthomatosis

Clinical, biochemical, and molecular insights into Cerebrotendinous Xanthomatosis: A nationwide study of 100 Turkish individuals

OBJECTIVE

Cerebrotendinous xanthomatosis (CTX) is an inherited metabolic disorder characterized by progressive neurologic and extraneurologic findings. The aim of this retrospective, descriptive study was to explore the time of presentation and diagnosis, and to expand the phenotype and genotype of CTX, based on a nationwide and comprehensive series of patients in Turkey.

METHODS

The demographic, clinical, biochemical and genotypic characteristics of the CTX patients were reviewed. Data on molecular analysis, age of onset and diagnosis, diagnostic delay, neurologic and extraneurologic symptomatology, results of plasma cholestanol levels, brain magnetic resonance imaging and electromyography at the time of diagnosis were reviewed.

RESULTS

100 confirmed CTX patients from 72 families were included. The mean age at diagnosis was 28.16 ± 14.28 years, and diagnostic delay was 18.39 ± 13.71 years. 36 patients were diagnosed in childhood. Frequency of intention tremor (p = 0.069), peripheral neuropathy (p = 0.234) and psychiatric manifestations (p = 0.396) did not differ between two groups, demonstrating the high rate in pediatric patients. Three adult patients showed a milder phenotype without neurologic involvement. Seven patients had normal plasma cholestanol levels despite neurological impairment. Sequencing of the CYP27A1 gene revealed 25 different variants, with a novel c.671_672del variant not previously described in literature.

CONCLUSION

Based on the observations of this Turkish CTX cohort, it is emphasized that the true prevalence of CTX is probably underestimated and that it has a wide spectrum of clinical phenotypes even without neurological impairment. In children, abnormal cerebellar findings, peripheral neuropathy and psychiatric findings associated with intellectual disability have been suggested as warning signs to avoid diagnostic delay. In cases of clinical suspicion, molecular analysis is recommended despite normal plasma cholestanol levels, as severe neurologic involvement may occur in CTX patients without elevated cholestanol levels.

Cerebrotendinous xanthomatosis with tremor as the main manifestation: A case report

INTRODUCTION

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid metabolism disorder. It is caused by a defect in the sterol-27-hydroxylase gene, leading to the deposition of cholesteryl and bile alcohol in large amounts, causing a variety of clinical manifestations; however, tremor as the main manifestation of CTX has not been reported.

PATIENTS CONCERNS AND CLINICAL FINDINGS

Herein, we report a 27-year-old woman, who developed head and body tremors at the age of 12 years. Many hospitals misdiagnosed her condition as idiopathic tremor and Parkinson disease, with a poor curative effect.

PRIMARY DIAGNOSIS AND INTERVENTION

We diagnosed her with CTX and treated with chenodeoxycholic acid and clonazepam.

CONCLUSION

The patient's condition considerably improved. This case could help avoid misdiagnosis and mistreatment in clinical practice.

Malar rash and hand tremor in early symptoms of cerebrotendinous xanthomatosis and the effect of chenodeoxycholic acid on them

BACKGROUND

Cerebrotendinous xanthomatosis (CTX, OMIM #213700) is a rare but treatable lipid storage disease resulting from mutations in the CYP27A1 gene.

PURPOSE

The study aims to evaluate patients diagnosed with CTX and reveal new information, especially about the signs of CTX and patients' response to the treatment.

METHODS

The study was conducted retrospectively in 12 definitively diagnosed CTX patients. The patients' clinical, laboratory, imaging, genetic findings, and CDCA (chenodeoxycholic acid) treatment results were analyzed.

RESULTS

The median age at diagnosis for the patients was 16.5 years (minimum-maximum: 7-32). Juvenile cataracts, detected in more than 90% (11/12) of the patients, were the most common clinical finding. Malar rash, not previously reported in the literature for CTX, was present in 75% (9/12) of the patients. Hand tremors, the first neurological symptom, occurred in adolescence and were the initial symptom of the disease in five patients. Hand tremors were present in 83.3% (10/12) of the patients. Hand tremors (in 5 patients) and malar rash (in 2 patients) were clinical findings with full recovery due to the CDCA treatment.

CONCLUSION

The study defines the malar rash finding, which has not been reported in the literature before, as a possible new clinical finding in CTX disease, attributed to its partial or full recovery with CDCA treatment. Additionally, as a novelty in the literature, our study highlights the full recovery of neurological findings, such as hand tremors, in CTX. Patients presenting with hand tremors and malar rash, especially in adolescence, should undergo CTX investigation for early diagnosis and treatment.

Cerebrotendinous Xanthomatosis patients with late diagnosed in single orthopedic clinic: two novel variants in the CYP27A1 gene

BACKGROUND

Cerebrotendinous Xanthomatosis (CTX) is a rare autosomal recessive lipid storage disorder caused by loss of function variants in the CYP27A1 gene which encodes sterol 27-hydroxylase, on chromosome 2q35. Although the symptoms begin commonly in infancy, CTX diagnosis is often delayed. The aim of this study is to review the orthopedic findings of the disease by providing an overview of the clinical features of the disease. It is to raise awareness of this condition for which early diagnosis and treatment are important.

METHODS

We retrospectively evaluated the clinical, laboratory, radiological, and genetic findings of eight patients from four families who were admitted to our Orthopedics and Traumatology Department between 2017 and 2022 due to bilateral Achilles tendon xanthomas, were found to have high cholestanol and CYP27A1 gene mutations.

RESULTS

The mean age of patients was 37, and five of them were male. The mean age at the onset of symptoms was 9.25 years. The mean age of initial diagnosis was 33.75 years. Between symptom onset and clinical diagnosis, an average delay of 24.5 years was observed. All patients had bilateral Achilles tendon xanthoma. Notably, a novel variant (c.670_671delAA) in CYP27A1 gene was identified in three patients who also presented with peripheral neuropathy and bilateral pes cavus. One patient had osteoporosis and four patients had osteopenia. Five patients had a history of bilateral cataracts. Furthermore, three of the patients had early-onset chronic diarrhea and three of the patients had ataxia. Two of the patients had epilepsy and seven of the patients had behavior-personality disorder. All patients had low intelligence, but none of them had cardiac disease.

CONCLUSION

We present the diagnostic process and clinical features which the largest CTX case series ever reported from single orthopedic clinic. We suggest that patients with normal cholesterol levels presenting with xanthoma being genetically analyzed by testing at their serum cholestanol level, and that all siblings of patients diagnosed with CTX be examined.

Cholestanol accelerates α-synuclein aggregation and spreading by activating asparagine endopeptidase

Cerebrotendinous xanthomatosis (CTX), an autosomal recessive disorder characterized by high levels of cholestanol in the blood and accumulation of cholestanol in multiple tissues, especially the brain, often presents in parkinsonism. However, it remains unknown whether cholestanol plays a role in the pathogenesis of sporadic Parkinson's disease (PD). Here, we show that the levels of serum cholestanol in patients with sporadic PD are higher than those in control participants. Cholestanol activates the protease asparagine endopeptidase (AEP) and induces the fragmentation of α-synuclein (α-syn) and facilitates its aggregation. Furthermore, cholestanol promotes the spreading of α-syn pathology in a mouse model induced by intrastriatal injection of α-syn fibrils. KO of AEP or administration of an AEP inhibitor ameliorates α-syn pathology, degeneration of the nigrostriatal dopaminergic pathway, and PD-like motor symptoms. These results not only indicate that cholestanol contributes to the aggregation and spreading of α-syn by activating AEP but also reveal an opportunity for treating PD with AEP inhibitors.

A case of cerebrotendinous xanthomatosis with massive xanthomas but without a considerable increase in serum cholestanol levels

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder caused by mutations in the sterol 27-hydroxylase gene (CYP27A1). Due to the deficiency of 27-hydroxylase, the synthesis of bile acids from cholesterol is impaired and excessive cholestanol accumulates in various tissues, such as the central nervous system, tendons, and lenses. Patients with CTX typically manifest intellectual decline, pyramidal tract symptoms, cerebellar symptoms, tendon xanthomas, juvenile cataracts, neonatal jaundice, chronic diarrhea, osteoporosis, and premature cardiovascular disease. Here, we report the atypical case of a 35-year-old female with CTX having massive xanthomas but without a considerable increase in serum cholestanol levels (3.9 µg/mL). In the differential diagnosis of xanthoma, CTX should not be ruled out even if the serum levels of cholestanol are not high, and genetic testing is necessary to make the appropriate diagnosis.

Characterization of Postprandial Bile Acid Profiles and Glucose Metabolism in Cerebrotendinous Xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a rare inherited disease characterized by sterol 27-hydroxylase (CYP27A1) deficiency and, thus, a lack of bile acid synthesis with a marked accumulation of 7α-hydroxylated bile acid precursors. In addition to their renowned lipid-emulgating role, bile acids have been shown to stimulate secretion of the glucose-lowering and satiety-promoting gut hormone glucagon-like peptide 1 (GLP-1). In this paper, we examined postprandial bile acid, glucose, insulin, GLP-1 and fibroblast growth factor 19 (FGF19) plasma profiles in patients with CTX and matched healthy controls. Seven patients and seven age, gender and body mass index matched controls were included and subjected to a 4 h mixed meal test with regular blood sampling. CTX patients withdrew from chenodeoxycholic acid (CDCA) and statin therapy three weeks prior to the test. Postprandial levels of total bile acids were significantly lower in CTX patients and consisted of residual CDCA with low amounts of ursodeoxycholic acid (UDCA). The postprandial plasma glucose peak concentration occurred later in CTX patients compared to controls, and patients' insulin levels remained elevated for a longer time. Postprandial GLP-1 levels were slightly higher in CTX subjects whereas postprandial FGF19 levels were lower in CTX subjects. This novel characterization of CTX patients reveals very low circulating bile acid levels and FGF19 levels, aberrant postprandial glucose and insulin profiles, and elevated postprandial GLP-1 responses.

Roles of bile acids signaling in neuromodulation under physiological and pathological conditions

Bile acids (BA) are important physiological molecules not only mediating nutrients absorption and metabolism in peripheral tissues, but exerting neuromodulation effect in the central nerve system (CNS). The catabolism of cholesterol to BA occurs predominantly in the liver by the classical and alternative pathways, or in the brain initiated by the neuronal-specific enzyme CYP46A1 mediated pathway. Circulating BA could cross the blood brain barrier (BBB) and reach the CNS through passive diffusion or BA transporters. Brain BA might trigger direct signal through activating membrane and nucleus receptors or affecting activation of neurotransmitter receptors. Peripheral BA may also provide the indirect signal to the CNS via farnesoid X receptor (FXR) dependent fibroblast growth factor 15/19 (FGF15/19) pathway or takeda G protein coupled receptor 5 (TGR5) dependent glucagon-like peptide-1 (GLP-1) pathway. Under pathological conditions, alterations in BA metabolites have been discovered as potential pathogenic contributors in multiple neurological disorders. Attractively, hydrophilic ursodeoxycholic acid (UDCA), especially tauroursodeoxycholic acid (TUDCA) can exert neuroprotective roles by attenuating neuroinflammation, apoptosis, oxidative or endoplasmic reticulum stress, which provides promising therapeutic effects for treatment of neurological diseases. This review summarizes recent findings highlighting the metabolism, crosstalk between brain and periphery, and neurological functions of BA to elucidate the important role of BA signaling in the brain under both physiological and pathological conditions.

Enzymatic activation in vitamin D signaling - Past, present and future

Vitamin D signaling is important in regulating calcium homeostasis essential for bone health but also displays other functions in cells of several tissues. Disturbed vitamin D signaling is linked to a large number of diseases. The multiple cytochrome P450 (CYP) enzymes catalyzing the different hydroxylations in bioactivation of vitamin D₃ are crucial for vitamin D signaling and function. This review is focused on the progress achieved in identification of the bioactivating enzymes and their genes in production of 1α,25-dihydroxyvitamin D₃ and other active metabolites. Results obtained on species- and tissue-specific expression, catalytic reactions, substrate specificity, enzyme kinetics, and consequences of gene mutations are evaluated. Matters of incomplete understanding regarding the physiological roles of some vitamin D hydroxylases are critically discussed and the authors will give their view of the importance of each enzyme for vitamin D signaling. Roles of different vitamin D receptors and an alternative bioactivation pathway, leading to 20-hydroxylated vitamin D₃ metabolites, are also discussed. Considerable progress has been achieved in knowledge of the vitamin D₃ bioactivating enzymes. Nevertheless, several intriguing areas deserve further attention to understand the pleiotropic and diverse activities elicited by vitamin D signaling and the mechanisms of enzymatic activation necessary for vitamin D-induced responses.

Allelic prevalence and geographic distribution of cerebrotendinous xanthomatosis

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is a rare recessive genetic disease characterized by disruption of bile acid synthesis due to inactivation of the CYP27A1 gene. Treatment is available in the form of bile acid replacement. CTX is likely underdiagnosed, and prevalence estimates based on case diagnosis are probably inaccurate. Large population-based genomic databases are a valuable resource to estimate prevalence of rare recessive diseases as an orthogonal unbiased approach building upon traditional epidemiological studies.

METHODS

We leveraged the Hardy-Weinberg principle and allele frequencies from gnomAD to calculate CTX prevalence. ClinVar and HGMD were used to identify high-confidence pathogenic missense variants and to calculate a disease-specific cutoff. Variant pathogenicity was also assessed by the VarSome implementation of the ACMG/AMP algorithm and the REVEL in silico predictor.

RESULTS

CTX prevalence estimates were highest in Asians (1:44,407-93,084) and lowest in the Finnish population (1:3,388,767). Intermediate estimates were found in Europeans, Americans, and Africans/African Americans (1:70,795-233,597). The REVEL-predicted pathogenic variants accounted for a greater increase in prevalence estimates for Europeans, Americans, and Africans/African Americans compared with Asians. We identified the most frequent alleles designated pathogenic in ClinVar (p.Gly472Ala, p.Arg395Cys), labeled pathogenic based on sequence consequence (p.Met1?), and predicted to be pathogenic by REVEL (p.Met383Lys, p.Arg448His) across populations. Also, we provide a prospective geographic map of estimated disease distribution based on CYP27A1 variation queries performed by healthcare providers from selected specialties.

CONCLUSIONS

Prevalence estimates calculated herein support and expand upon existing evidence indicating underdiagnosis of CTX, suggesting that improved detection strategies are needed. Increased awareness of CTX is important for early diagnosis, which is essential for patients as early treatment significantly slows or prevents disease progression.

A Rare Case of Cerebrotendinous Xanthomatosis Associated With a Mutation on COG8 Gene

Cerebrotendinous xanthomatosis (CTX) is a rare hereditary disease described by a mutation in the CYP27A1 gene, which encodes the sterol 27-hydroxylase enzyme involved in the synthesis of bile acid. Accumulation of cholesterol and its metabolite, cholestanol, in multiple body organs causes the symptoms of this disease. In addition, a mutation in the COG8 gene, which encodes a subunit of conserved oligomeric Golgi (COG) complex, causes another rare disorder attributed to type IIh of congenital disorder of glycosylation (CDG). We described a rare case of CTX disorder associated with a mutation on COG8 gene, which presented by unusual symptoms.

Case report: Cerebrotendinous xanthomatosis with a novel mutation in the CYP27A1 gene mimicking behavioral variant frontotemporal dementia

Background

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid storage disease caused by a mutation in the CYP27A1 gene. Due to the disruption of bile acid synthesis leading to cholesterol and cholestanol accumulation, CTX manifests as premature cataracts, chronic diarrhea, and intellectual disability in childhood and adolescence. This report presents a case of CTX with an unusual phenotype of behavioral variant frontotemporal dementia (bvFTD) in middle age.

Case presentation

A 60-year-old woman presented with behavioral and personality changes. She showed disinhibition, such as hoarding and becoming aggressive over trifles; compulsive behavior, such as closing doors; apathy; and dietary change. The patient showed a progressive cognitive decline and relatively sparing memory and visuospatial function. She had hyperlipidemia but no family history of neurodegenerative disorders. Initial fluid-attenuated inversion recovery (FLAIR) images showed a high signal in the periventricular area, and brain spectroscopy showed hypoperfusion in the frontal and temporal lobes, mimicking bvFTD. However, on physical examination, xanthomas were found on both the dorsum of the hands and the Achilles tendons. Hyperactive deep tendon reflexes in the bilateral biceps, brachioradialis, and knee and positive Chaddock signs on both sides were observed. Four years later, FLAIR images showed symmetrical high signals in the bilateral dentate nuclei of the cerebellum. Her serum cholestanol (12.4 mg/L; normal value ≤6.0) and 7α,12α-dihydroxycholest-4-en-3-one (0.485 nmol/mL; normal value ≤0.100) levels were elevated. A novel likely pathogenic variant (c.1001T>A, p.Met334Lys) and a known pathogenic variant (c.1420C>T, p.Arg474Trp) of the CYP27A1 gene were found in trans-location. The patient was diagnosed with CTX and prescribed chenodeoxycholic acid (750 mg/day).

Conclusions

This report discusses the case of a middle-aged CTX patient with an unusual phenotype of bvFTD. A novel likely pathogenic variant (c.1001T>A, p.Met334Lys) was identified in the CYP27A1 gene. Early diagnosis is important because supplying chenodeoxycholic acid can prevent CTX progression.

Clinical, electrophysiological, and genetic characteristics of cerebrotendinous xanthomatosis in South Korea

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disorder caused by 27-hydroxylase deficiency. We report the clinical characteristics of six Korean CTX patients. The median age of onset was 22.5 years, the median age at diagnosis was 42 years, and the diagnostic delay was 18.1 years. The most common clinical symptoms were tendon xanthoma and spastic paraplegia. Four of five patients exhibited latent central conduction dysfunction. All patients carried the same mutation in CYP27A1 (c.1214 G>A [p.R405Q]). CTX is a treatable neurodegenerative disorder; however, our results revealed that patients with CTX in Korea might receive the diagnosis after a prolonged delay.    .

Liver transplantation in an infant with cerebrotendinous xanthomatosis, cholestasis, and rapid evolution of liver failure

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is a disorder of bile acid (BA) metabolism due to biallelic mutations in CYP27A1. The deposition of cholesterol and cholestanol in multiple tissues results, manifesting as neurologic disease in adults or older children. Neonatal cholestasis (NC) as a presentation of CTX is rare; it may self-resolve or persist, evolving to require liver transplantation (LT).

METHODS

We present in the context of similar reports an instance of CTX manifest as NC and requiring LT.

RESULTS

A girl aged 4mo was evaluated for NC with normal serum gamma-glutamyl transpeptidase activity. An extensive diagnostic work-up, including liver biopsy, identified no etiology. Rapid progression to end-stage liver disease required LT aged 5mo. The explanted liver showed hepatocyte loss and micronodular cirrhosis. Bile salt export pump (BSEP), encoded by ABCB11, was not demonstrable immunohistochemically. Both severe ABCB11 disease and NR1H4 disease-NR1H4 encodes farsenoid-X receptor, necessary for ABCB11 transcription-were considered. However, selected liver disorder panel sequencing and mass-spectrometry urinary BA profiling identified CTX, with homozygosity for the predictedly pathogenic CYP27A1 variant c.646G > C p.(Ala216Pro). Variation in other genes associated with intrahepatic cholestasis was not detected. Immunohistochemical study of the liver-biopsy specimen found marked deficiency of CYP27A1 expression; BSEP expression was unremarkable. Aged 2y, the girl is free from neurologic disease.

CONCLUSIONS

Bile acid synthesis disorders should be routinely included in the NC/"neonatal hepatitis" work-up. The mutually supportive triple approach of BA profiling, immunohistochemical study, and genetic analysis may optimally address diagnosis in CTX, a treatable disease with widely varying presentation.

Differing clinical features between Japanese siblings with cerebrotendinous xanthomatosis with a novel compound heterozygous CYP27A1 mutation: a case report

Background

Cerebrotendinous xanthomatosis (CTX) is an autosomal-recessive lipid storage disorder caused by mutations in the CYP27A1 gene encoding the key enzyme in the bile acid synthesis, sterol 27-hydroxylase. Here, we report two Japanese CTX siblings with a novel compound heterozygous CYP27A1 mutation, showing different clinical phenotypes and responses to chenodeoxycholic acid (CDCA) therapy.

Case presentation

The proband, a 32-year-old man, who had chronic diarrhea, bilateral cataracts, and xanthomas, demonstrated progressive neurological manifestations including ataxia, and spastic paraplegia during a 5-year follow-up period despite normalization of serum cholestanol after initiation of CDCA treatment. He also exhibited cognitive decline although improvement had been observed at the beginning of treatment. Follow-up brain magnetic resonance imaging (MRI) revealed pronounced progressive atrophy in the cerebellum, in addition to expanding hyperintense lesions in the dentate nuclei, posterior limb of the internal capsule, cerebral peduncles, and inferior olives on T2-weighted images. In contrast, the two-year-younger sister of the proband presented with chronic diarrhea, cataracts, xanthomas, and intellectual disability but no other neurological symptoms at the time of diagnosis. CDCA treatment lead to improvement of cognitive function and there were no characteristic CTX-related MRI features during the follow-up period. The siblings shared a paternally inherited c.1420C > T mutation (p.Arg474Trp) and a maternally inherited novel c.1176_1177delGA mutation, predicting p.(Glu392Asp*20).

Conclusions

Our cases suggest that early diagnosis and subsequent initiation of CDCA treatment are crucial before the appearance of characteristic MRI findings and severe neurological manifestations related to CTX. Further studies are required to elucidate mechanisms responsible for the clinical diversity of CTX and prognostic factors for long-term outcomes following initiation of CDCA treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02711-4.

Rapidly progressive dementia and intractable diarrhea: a teaching case report and a systematic review of cognitive impairment in Whipple’s disease

Objective

Methods

Results

Conclusions

Supplementary Information

Cerebrotendinous xanthomatosis without neurological involvement

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessively inherited inborn error of metabolism. Neurological symptoms are considered to be a clinical hallmark of untreated adult patients. We describe a 'milder CTX phenotype', without neurological involvement.

METHODS

We performed a retrospective patient file study in 79 genetically confirmed Dutch patients with CTX (55 patients aged ≥ 21 years) to study the clinical heterogeneity of CTX. We studied the frequency of adult patients with CTX without neurological involvement at diagnosis, in our Dutch cohort, and included a family from South Africa and patients from Italy, USA, Chile and Asia from the literature.

RESULTS

In total, we describe 19 adult patients with CTX from 16 independent families, without neurological symptoms at diagnosis. A relatively small percentage (21%, n = 4) had a history of cataract. The majority, 84% (n = 16), presented with tendon xanthomas as the sole or predominant feature. The majority of patients showed increased plasma cholesterol levels. No correlation was found between this 'milder phenotype', the cholestanol levels and the CYP27A1 genotype. In addition, we describe three novel mutations in the CYP27A1 gene.

CONCLUSIONS

This study shows the clinical heterogeneity of CTX, highlighting the existence of a 'milder phenotype', that is without neurological involvement at diagnosis. Adult patients with CTX may present with tendon xanthomas as the sole or predominant feature, mimicking familial hypercholesterolemia. It is important to realize that the absence of neurological symptoms does not rule out the development of future neurological symptoms. As CTX is a treatable disorder, early diagnosis and initiation of treatment when additional clinical signs occur is therefore essential.

First case series of Polish patients with cerebrotendinous xanthomatosis and systematic review of cases from the 21st century

Cerebrotendinous xanthomatosis (CTX) is an inborn error of metabolism caused by recessive variants in the cytochrome P450 CYP27A1 gene. CTX is said to manifest with childhood-onset chronic diarrhea and the classic triad of juvenile-onset cataracts, Achilles tendons xanthomas, and progressive ataxia. It is currently one of the few inherited neurometabolic disorders amenable to a specific treatment. The diagnosis may be significantly delayed resulting in permanent neurological impairment. A retrospective review of the clinical characteristics and diagnostic findings in case series of six Polish patients with CTX. Additional retrospective review of symptoms and pathogenic variants of 568 CTX available cases and case series from the past 20 years. To the best of our knowledge, this is the widest review of CTX cases reported in years 2000-2021. We report the largest cohort of Polish patients ever published, with the identification of two hot-spot mutations. During the review of available 568 cases, we found significant differences in the clinical phenotypes and the localization of variants within the gene between Asian and non-Asian populations. These findings may facilitate molecular testing in the Polish and Asian populations. Invariably better screening for CTX and wider awareness is needed.

Prevalence of cerebrotendinous xanthomatosis in cases with idiopathic bilateral juvenile cataract in ophthalmology clinics in Turkey

PURPOSE

To determine the prevalence of cerebrotendinous xanthomatosis (CTX) in patients with idiopathic bilateral juvenile cataract in Turkey.

METHODS

In this multicenter, epidemiologic observational study, patients with idiopathic bilateral juvenile cataract (aged ≥1 year at study entry) were identified from the records of 31 ophthalmology clinics. The Mignarri suspicion index determined in all potential CTX patients; blood samples were collected, and genetic testing for CYP27A1 gene mutation was performed. Cholestanol levels of the patients were measured, and those with a level of ≥3.75 μg/mL (threshold value) underwent genetic testing for mutations in the CYP27A1 gene.

RESULTS

CTX was diagnosed in 7 of 452 patients (1.55%) with bilateral juvenile cataract. There was no significant difference between patients with a Mignarri score of <100 (n = 8) and those with a score of ≥100 (n = 19) with respect to cholestanol levels and genetic test results. Genetic testing was undertaken in 27 patients based on elevated cholestanol levels. Of these 27, 7 (26%) had CYP27A1 gene mutations. Of these 7 patients with genetically confirmed CTX, 5 (71%) were in the group with higher Mignarri score (≥100).

CONCLUSIONS

CTX is a treatable condition, and early detection is crucial for avoiding irreversible neurological manifestations. Screening using the Mignarri suspicion index and cholestanol blood levels can be helpful in identifying suspected cases of CTX.

Gene supplementation of CYP27A1 in the liver restores bile acid metabolism in a mouse model of cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease caused by mutations in the CYP27A1 gene, encoding the sterol 27-hydroxylase. Disruption of the bile acid biosynthesis pathway and accumulation of toxic precursors such as cholestanol cause chronic diarrhea, bilateral juvenile cataracts, tissue deposition of cholestanol and cholesterol (xanthomas), and progressive motor/neuropsychiatric alterations. We have evaluated the therapeutic potential of adeno-associated virus (AAV) vectors expressing CYP27A1 in a CTX mouse model. We found that a vector equipped with a strong liver-specific promoter (albumin enhancer fused with the α1 anti-trypsin promoter) is well tolerated and shows therapeutic effect at relatively low doses (1.5 × 10¹² viral genomes [vg]/kg), when less than 20% of hepatocytes overexpress the transgene. This vector restored bile acid metabolism and normalized the concentration of most bile acids in plasma. By contrast, standard treatment (oral chenodeoxycholic acid [CDCA]), while reducing cholestanol, did not normalize bile acid composition in plasma and resulted in supra-physiological levels of CDCA and its derivatives. At the transcriptional level, only the vector was able to avoid the induction of xenobiotic-induced pathways in mouse liver. In conclusion, the overexpression of CYP27A1 in a fraction of hepatocytes using AAV vectors is well tolerated and provides full metabolic restoration in Cyp27a1^−/− mice. These features make gene therapy a feasible option for the etiological treatment of CTX patients.

Expert opinion on diagnosing, treating and managing patients with cerebrotendinous xanthomatosis (CTX): a modified Delphi study

Background

Cerebrotendinous xanthomatosis (CTX) is a rare, chronic, progressive, neurodegenerative disorder requiring life-long care. Patients with CTX often experience a diagnostic delay. Although early diagnosis and treatment initiation can improve symptoms and prognosis, a standardised approach to diagnosis, treatment and management of patients is not yet established.

Aim

To assess expert opinion on best care practices for patients with CTX using a modified Delphi method.

Methods

A multidisciplinary group of healthcare professionals with expertise in CTX responded to a 3-round online questionnaire (n = 10 in Rounds 1 and 2; n = 9 in Round 3), containing questions relating to the diagnosis, treatment, monitoring, multidisciplinary care and prognosis of patients with CTX. Determination of consensus achievement was based on a pre-defined statistical threshold of ≥ 70% Delphi panellists selecting 1–2 (disagreement) or 5–6 (agreement) for 6-point Likert scale questions, or ≥ 70% Delphi panellists choosing the same option for ranking and proportion questions.

Results

Of the Round 1 (n = 22), Round 2 (n = 32) and Round 3 (n = 26) questions for which consensus was assessed, 59.1%, 21.9% and 3.8% reached consensus, respectively. Consensus agreement that genetic analyses and/or determination of serum cholestanol levels should be used to diagnose CTX, and dried bloodspot testing should facilitate detection in newborns, was reached. Age at diagnosis and early treatment initiation (at birth, where possible) were considered to have the biggest impact on treatment outcomes. All panellists agreed that chenodeoxycholic acid (CDCA) is a lifetime replacement therapy which, if initiated early, can considerably improve prognosis as it may be capable of reversing the pathophysiological process in CTX. No consensus was reached on the value of cholic acid therapy alone. Monitoring patients through testing plasma cholestanol levels and neurologic examination was recommended, although further research regarding monitoring treatment and progression of the disease is required. Neurologists and paediatricians/metabolic specialists were highlighted as key clinicians that should be included in the multidisciplinary team involved in patients’ care.

Conclusions

The results of this study provide a basis for standardisation of care and highlight key areas where further research is needed to inform best practices for the diagnosis, treatment and management of patients with CTX.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01980-5.

Genetic diseases mimicking multiple sclerosis

Multiple sclerosis (MS) is an inflammatory neurodegenerative disorder manifesting as gradual or progressive loss of neurological functions. Most patients present with relapsing-remitting disease courses. Extensive research over recent decades has expounded our insights into the presentations and diagnostic features of MS. Groups of genetic diseases, CADASIL and leukodystrophies, for example, have been frequently misdiagnosed with MS due to some overlapping clinical and radiological features. The delayed identification of these diseases in late adulthood can lead to severe neurological complications. Herein we discuss genetic diseases that have the potential to mimic multiple sclerosis, with highlights on clinical identification and practicing pearls that may aid physicians in recognizing MS-mimics with genetic background in clinical settings.

Cerebrotendinous Xanthomatosis: Molecular Pathogenesis, Clinical Spectrum, Diagnosis, and Disease-Modifying Treatments

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disorder caused by mutations in the CYP27A1 gene, which encodes the mitochondrial enzyme sterol 27-hydroxylase. Decreased sterol 27-hydroxylase activity results in impaired bile acid synthesis, leading to reduced production of bile acids, especially chenodeoxycholic acid (CDCA), as well as elevated serum cholestanol and urine bile alcohols. The accumulation of cholestanol and cholesterol mainly in the brain, lenses, and tendons results in the characteristic clinical manifestations of CTX. Clinical presentation is characterized by systemic symptoms including neonatal jaundice or cholestasis, refractory diarrhea, juvenile cataracts, tendon xanthomas, osteoporosis, coronary heart disease, and a broad range of neuropsychiatric manifestations. The combinations of symptoms vary from patient to patient and the presenting symptoms, especially in the early disease phase, may be nonspecific, which leads to a substantial diagnostic delay or underdiagnosis. Replacement of CDCA has been approved as a first-line treatment for CTX, and can lead to biochemical and clinical improvements. However, the effect of CDCA treatment is limited once significant neuropsychiatric manifestations are established. The age at diagnosis and initiation of CDCA treatment correlate with the prognosis of patients with CTX. Therefore, early diagnosis and subsequent treatment initiation are essential.

Cerebrotendinous xanthomatosis revisited

Cerebrotendinous xanthomatosis is a rare autosomal recessive lipid storage syndrome defined clinically by the triad of progressive neurodegeneration, juvenile cataracts and tendon xanthomas in adults. It is treatable, and a prompt diagnosis can improve outcomes. We describe a patient with this condition who presented with progressive ataxia.

Clinical and Genetic Characteristics of Splicing Variant in CYP27A1 in an Iranian Family with Cerebrotendinous Xanthomatosis

Background:

CTX is a rare congenital lipid-storage disorder, leading to a progressive multisystem disease. CTX with autosomal recessive inheritance is caused by a defect in the CYP27A1 gene. Chronic diarrhea, tendon xanthomas, neurologic impairment, and bilateral cataracts are common symptoms of the disease.

Methods:

Three affected siblings with an initial diagnosis of non-syndromic intellectual disability were recruited for further molecular investigations. To identify the possible genetic cause(s), WES was performed on the proband. Sanger sequencing was applied to confirm the final variant. The clinical and molecular genetic features of the three siblings from the new CTX family and other patients with the same mutations, as previously reported, were analyzed. The CYP27A1 gene was also studied for the number of pathogenic variants and their location.

Results:

We found a homozygous splicing mutation, NM_000784: exon6: c.1184+1G>A, in CYP27A1 gene, which was confirmed by Sanger sequencing. Among the detected pathogenic variants, the splice site mutation had the highest prevalence, and the mutations were mostly found in exon 4.

Conclusion:

This study is the first to report the c.1184+1G>A mutation in Iran. Our findings highlight the other feature of the disease, which is the lack of relationship between phenotype and genotype. Due to nonspecific symptoms and delay in diagnosis, CYP27A1 genetic analysis should be the definitive method for CTX diagnosis.

Challenges and Controversies in the Genetic Diagnosis of Hereditary Spastic Paraplegia

Purpose of Review

The hereditary spastic paraplegias (HSPs) are a group of disorders characterised by progressive lower limb weakness and spasticity. We address the challenges and controversies involved in the genetic diagnosis of HSP.

Recent Findings

There is a large and rapidly expanding list of genes implicated in HSP, making it difficult to keep gene testing panels updated. There is also a high degree of phenotypic overlap between HSP and other disorders, leading to problems in choosing the right panel to analyse. We discuss genetic testing strategies for overcoming these diagnostic hurdles, including the use of targeted sequencing gene panels, whole-exome sequencing and whole-genome sequencing. Personalised treatments for HSP are on the horizon, and a genetic diagnosis may hold the key to access these treatments.

Summary

Developing strategies to overcome the challenges and controversies in HSP may hold the key to a rapid and accurate genetic diagnosis.

Spinal cerebrotendinous xanthomatosis: A case report and literature review

Background

Classic cerebrotendinous xanthomatosis (CTX; OMIM #213700) manifests with chronic diarrhea, juvenile cataracts, tendon xanthomas and neurological symptoms. It is due to biallelic inactivation of CYP27A1 wich leads to cholestanol accumulation in the central nervous system, eyes and tendons. Less commonly, the disease can present in young adults as spastic paraparesis in the absence of xanthomas.

Case presentation

We report a 38-year old woman who presented with chronic diarrhea and progressive spastic paraparesis in her twenties. Brain magnetic resonance imaging (MRI) showed cerebral atrophy with diffuse periventricular white matter hyperintensities. Spinal MRI was normal. CYP27A1 gene sequencing confirmed the diagnosis of CTX. Chenodeoxycholic acid (CDCA) treatment was introduced with remission of diarrhea. Unfortunately, the treatment had to be discontinued several times and the patient developed psychosis and an severe ataxospastic gait. Spinal MRI revealed new linear hyperintensities of the corticospinal and gracile tracts. Thirty-three spinal CTX patients were identified by searching in Pubmed, EMBASE™ and Web of Science databases. All patients presented pyramidal signs and 48% had dorsal column signs. Juvenile cataracts were described in 78% of patients, chronic diarrhea in 65%, and tendon xanthomas in 31%. Disease improvement or stabilization with chenodeoxycholic acid was observed in 69% of patients. A higher prevalence of the Arg395Cys allele was observed in patients with spinal CTX as compared to CTX in general (ᵡ²; p < 0.00001).

Conclusions

The diagnosis of spinal CTX can be easily missed or delayed in absence of xanthomas. There is a higher prevalence of the Arg395Cys allele in spinal CTX as compared to classic childhood-onset CTX. CDCA treatment seems to stabilize or improve clinical symptoms in most patients. However, as seen in our patient and in two previously reported cases, sudden interruption of CDCA may lead to irreversible neurological complications.

Late-Onset Leukodystrophy Mimicking Hereditary Spastic Paraplegia without Diffuse Leukodystrophy on Neuroimaging

PURPOSE

Leukodystrophies are frequently regarded as childhood disorders, but they can occur at any age, and the clinical and imaging patterns of the adult-onset form are usually different from the better-known childhood variants. Several reports have shown that various late-onset leukodystrophies, such as X-linked adrenoleukodystrophy and Krabbe disease, may present as spastic paraplegia with the absence of the characteristic white matter lesions on neuroimaging; this can be easily misdiagnosed as hereditary spastic paraplegia. The objective of this study was to investigate the frequency of late-onset leukodystrophies in patients with spastic paraplegia.

PATIENTS AND METHODS

We performed genetic analysis using a custom-designed gene panel for leukodystrophies in 112 hereditary spastic paraplegia-like patients.

RESULTS

We identified pathogenic mutations in 13 out of 112 patients, including five patients with adrenomyeloneuropathy, three with Krabbe disease, three with Alexander disease, and two with cerebrotendinous xanthomatosis. In terms of clinical manifestations, in addition to spastic paraplegia, three adrenomyeloneuropathy probands also had adrenocortical insufficiency, two Alexander disease probands developed urinary retention, one CTX proband developed cataracts and chronic diarrhea and the other presented with chronic diarrhea and mild tendon xanthomatosis. None of the patients had evidence of diffuse leukodystrophy on neuroimaging.

CONCLUSION

Patients with late-onset spastic paraplegia should be screened for underlying leukodystrophies, irrespective of the presence of additional complicating symptoms and neuroimaging abnormalities.

Cholestasis as a dominating symptom of patients with CYP27A1 mutations: An analysis of 17 Chinese infants

BACKGROUND

CYP27A1 is the disease-causing gene of cerebrotendinous xanthomatosis (CTX). As a treatable lipid storage disease, early treatment can improve the prognosis. However, CTX patients reported in the literature are mostly adult patients; the phenotype spectrum of CTX in the infantile population remains elusive.

OBJECTIVE

We aimed to investigate the phenotype spectrum of infants who carried pathogenic or likely pathogenic variants in the CYP27A1 gene and were suspected of having CTX.

METHODS

From June 2014 to May 2020, infants with pathogenic or likely pathogenic variants in CYP27A1 gene were enrolled, who underwent next-generation sequencing or Sanger sequencing in Children's Hospital of Fudan University. Patient characteristics, clinical treatments and outcomes were extracted from electronic medical records.

RESULTS

A total of 17 patients with an average onset age of 8 (1-42) days were found. The average diagnosis age was ten months. Cholestasis was the dominant symptom of these infants. Thirteen variants were detected, of which c.379C > T was a hotspot variant (26.5% alleles, 9/34). Cholestatic CTX is usually underestimated, but it could be severe or even fatal in infancy. For outcomes, 5 suffered from liver failure (36%, 5/14), 1 still showed cholestasis (7%, 1/14), 7 were asymptomatic (50%, 7/14), and 1 presented seizure and developmental delay in later childhood (7%, 1/14).

CONCLUSION

Based on this infantile cohort, we concluded that it is necessary to consider the possibility of CTX caused by CYP27A1 gene variants for infants with cholestasis.

Cerebrotendinous xanthomatosis with peripheral neuropathy: a clinical and neurophysiological study in Chinese population

Background

Cerebrotendinous xanthomatosis (CTX) is an inborn disorder of bile acid metabolism caused by deficiency of sterol 27-hydroxylase (CYP27A1) gene. CTX-related peripheral neuropathy has rarely been discussed in Chinese population. Here, we reported 6 CTX cases and performed a literature review focused on CTX with neuropathy to summarize its clinical and neurophysiological features.

Methods

All clinical data of 6 CTX cases were collected, and 21 reported Chinese CTX patients (including this study) were reviewed and summarized.

Results

Clinical manifestations of 6 CTX cases showed great heterogeneity. Cognitive decline, spastic paraplegia, cerebellar ataxia and advanced bulbar palsy were common neurological disorders, often accompanied by non-neurological signs like xanthomas, cataract, diarrhea and pes cavus. Dentate nuclei hyperintensity with or without hyposignal is a valuable MRI hallmark. Pooling our patients and literature review together, peripheral neuropathy was predominant sensorimotor demyelinating type in Chinese population, with an evident length dependent pattern and increased vulnerability in motor nerves. Demyelinating and axonal degeneration tend to exist in severe neuropathy. Three novel mutations including c.1055C>A; c.432T>G; c.472T>G were identified in CYP27A1 and predicted to be pathogenic. Oral CDCA therapy could ameliorate some of the existing symptoms and provide clinical stability, but it could not cease disease progression completely.

Conclusions

Our study broadens the phenotype and mutation spectrum of CTX. Patients with cognitive decline, spastic tetraparesis, cerebellar ataxia and bulbar palsy, should be highly suspicious of CTX even no xanthomas disclosed. Peripheral neuropathy was predominant sensorimotor demyelinating type in Chinese population, with mixed axonal and demyelinating type in severe cases. Three novel likely pathogenic mutations including c.1055C>A; c.432T>G; c.472T>G were identified in CYP27A1.

c.1263+1G>A Is a Latent Hotspot for CYP27A1 Mutations in Chinese Patients With Cerebrotendinous Xanthomatosis

Background

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disorder of bile acid synthesis caused by mutations in the CYP27A1 gene. CTX is an underdiagnosed and potentially treatable disease, thus a detailed appreciation of the phenotypic spectrum and genetic characteristics are crucial for early diagnosis and treatment.

Objectives and Methods

Four CTX families with mutations in the CYP27A1 gene were enrolled in our study. We investigated the clinical characteristics and molecular genetic features of the probands with CTX. Genetic analysis was performed for detecting gene variants. Sanger sequencing and segregation analysis were conducted for haplotype analysis.

Results

All the four probands were compound heterozygote for two CYP27A1 variants, including one mutation in c.1263+1G>A (intron 7) splice site, two novel likely pathogenic mutations (c.255+1G>T and c.1561dupA) and three pathogenic mutations including c.379C>T, c.1263+1G>A and c.1537C>T previously reported. All of the subjects presented with spastic paraparesis. The other common clinical features included ataxia, childhood-onset diarrhea, cataracts, intellectual disability, tendinous xanthomas and dentate nuclei signal alterations at MRI.

Conclusion

Two novel likely pathogenic mutations (c.255+1G>T and c.1561dupA) were reported in our study. The 1263+1G>A mutation was commonly seen in Chinese reported case series (7/25, 28%) and could be a latent hotspot for Chinese CTX mutations. Our study expanded the mutation spectrum of CYP27A1 gene and provide an insightful view of the phenotypic spectrum and genetic characteristics to help early diagnosis and treatment with to improve neurologic dysfunction.

Toward newborn screening of cerebrotendinous xanthomatosis: results of a biomarker research study using 32,000 newborn dried blood spots

Purpose

Cerebrotendinous xanthomatosis (CTX) is a treatable hereditary disorder caused by the deficiency of sterol 27- hydroxylase, which is encoded by the CYP27A1 gene. Different newborn screening biomarkers for CTX have been described, including 7α,12α-dihydroxy-4-cholesten-3-one ( 7α12αC4 ), 5b-cholestane-3 α, 7α,12α,25-tetrol glucuronide(GlcA-tetrol), GlcA-tetrol to tauro-chenodeoxycholic acid (t-CDCA) ratio (GlcA-tetrol/t-CDCA), and tauro- trihydroxycholestanoic acid (t-THCA) to GlcA-tetrol ratio (t-THCA/GlcA-tetrol ). We set out to evaluate these screening methods in a research study using 32,000–55,000 newborn dried blood spots (DBS).

Method

Metabolites were extracted from DBS with methanol containing internal standard, which was then quantified by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS).

Results

The measurement of 7α12αC4 was complicated by isobaric interferences and was discontinued after 2,033 samples. A total of 55,250 newborns were screened for the GlcA-tetrol/t-CDCA ratio, 32,737 of which had quantitative data on GlcA-tetrol. Only one newborn displayed both highly elevated GlcA-tetrol and a typical CTX biochemical profile. This newborn was interpreted as a CTX-affected patient as CYP27A1 gene sequencing identified two known pathogenic variants.

Conclusion

The results indicate that both GlcA-tetrol and GlcA-tetrol/t-CDCA ratio are excellent CTX biomarkers suitable for newborn screening. By characterizing the relationship of GlcA-tetrol, t-CDCA, and t-THCA as secondary markers, 100% assay specificity can be achieved.

A Neuropsychological Profile for Cerebrotendinous Xanthomatosis: A Single-Case Study

OBJECTIVE

Cerebrotendinous xanthomatosis (CTX) belongs to a heterogeneous group of neurological disorders known as autosomal recessive cerebellar ataxias. Low awareness of CTX can result in misdiagnoses in the differential diagnostic process and may limit one's ability to offer suitable recommendations. While neurodegeneration is a recognized manifestation of CTX, there is scant literature to characterize the nature of cortical symptoms and even less detailing of its associated neurocognitive and neuropsychiatric manifestations.

METHOD

Based on the lack of representation of CTX in neuropsychological literature, we sought to present a case seen in a 39-year-old patient within our own clinic.

RESULTS

Evaluation of the patient's neurocognitive functioning revealed global impairment consistent with a CTX diagnosis and neuroimaging findings noting significant cerebellar involvement.

CONCLUSIONS

Neuropsychologists are increasingly called upon to make treatment recommendations and provide information that may be helpful in differential diagnosis as part of multidisciplinary teams. Referrals from neurology are common, and it is important for neuropsychologists to be aware of diseases that affect the central nervous system; CTX is one such example. The goal of this case study is to build awareness of this condition and increase interest in a more systematic approach to research and clinical care of this population.

Multi-imaging study in a patient with cerebrotendinous xanthomatosis: radiology, clinic and pathology correlation of a rare condition

Cerebrotendinous xanthomatosis (CTX) is a rare metabolic disease with autosomal recessive inheritance. It is caused by mutations of the CYP27A1 gene, which codifies for sterol 27-hydroxylase, an enzyme that is responsible for the synthesis of cholic acids. In CTX, cholic acid synthesis is impaired, leading to accumulation of the precursor chenodessossicholic acid) in various organs and tissues. The clinical manifestations of CTX include chronic diarrhea, early-onset cataracts, tendon xanthomas and neurological disturbances. Therapy with oral chenodessossicholic acid has been shown to provide significantly better outcomes for affected individuals; therefore, recognition of this disease and awareness of its suggestive instrumental signs is extremely important. In this study, we describe the imaging findings in a 43-years-old male who was diagnosed with CTX and studied through ultrasound, CT and MRI.

It is important that the neurology and radiology communities are aware of this multi-imaging findings: recognition of them is important, as due to the high variability of the manifestation of this disease; it could impact on early diagnosis of a condition rarely seen, but manageable.

Clinical and genetic characteristics of Chinese patients with cerebrotendinous xanthomatosis

Background

Cerebrotendinous xanthomatosis (CTX) is a rare inborn lipid-storage disease caused by mutations in the sterol 27-hydroxylase (CYP27A1) gene with an autosomal recessive pattern of inheritance. To date, only 19 CTX patients from 16 families have been reported in the Chinese population.

Results

Three novel likely pathogenic mutations (c.368_374delCCAGTAC, c.389 T > A and c.571C > T) and 7 previously reported pathogenic mutations (c.379C > T, c.435G > T, c.1016C > T, c.1214G > A, c.1263 + 1G > A, c.1420C > T and c.1435C > T) were identified. In addition, we summarized the genotypes and phenotypes of reported Chinese CTX patients. The most predominant mutations in CYP27A1 were c.410G > A and c.379C > T, and the most common clinical manifestations were pyramidal signs, xanthomatosis, cerebellar ataxia, and cognitive impairment.

Conclusion

Our study broadens the genetic and clinical spectrum of CTX and provides insightful information to help better diagnose and understand the disease.

Clinical and genetic characteristics of Chinese patients with cerebrotendinous xanthomatosis

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is a rare inborn lipid-storage disease caused by mutations in the sterol 27-hydroxylase (CYP27A1) gene with an autosomal recessive pattern of inheritance. To date, only 19 CTX patients from 16 families have been reported in the Chinese population.

RESULTS

Three novel likely pathogenic mutations (c.368_374delCCAGTAC, c.389 T > A and c.571C > T) and 7 previously reported pathogenic mutations (c.379C > T, c.435G > T, c.1016C > T, c.1214G > A, c.1263 + 1G > A, c.1420C > T and c.1435C > T) were identified. In addition, we summarized the genotypes and phenotypes of reported Chinese CTX patients. The most predominant mutations in CYP27A1 were c.410G > A and c.379C > T, and the most common clinical manifestations were pyramidal signs, xanthomatosis, cerebellar ataxia, and cognitive impairment.

CONCLUSION

Our study broadens the genetic and clinical spectrum of CTX and provides insightful information to help better diagnose and understand the disease.

Early diagnosed cerebrotendinous xanthomatosis patients: clinical, neuroradiological characteristics and therapy results of a single center from Turkey

Cerebrotendinous xanthomatosis (CTX) is a lipid storage disorder caused by defective sterol 27-hydroxylase activity. In spite of subtle clinical signs beginning from childhood, CTX is generally diagnosed lately. The aim of this study is to evaluate clinical, neuroradiological findings and therapy responses of pediatric CTX patients and raise awareness to early features of disease. Patients who were molecularly diagnosed as CTX before 18 years of age were included in study. Clinical, epidemiological, radiological and genotypic features of patients and chenodeoxycholic acid (CDCA) therapy responses were reviewed retrospectively. Six patients were enrolled in the study. The mean age of diagnosis was 11.1 ± 4.5 years. Apart from previous studies, predominance of cerebellar signs over pyramidal signs, peripheral neuropathy with demyelinating neuropathy in majority of patients and pathological brain imaging findings despite young ages of patients were observed. Intention tremor was the consisting finding of all patients. Optic disc drusen was initially reported in one patient. Skeletal system involvement as coarse extremities, deformities and early osteoporosis was recognized in four patients. CDCA therapy improved or at least stabilized neurological functions in all patients. This study is the first CTX series from Turkey and performed among only in early diagnosed patients with a therapy follow-up contrary to limited data in the literature. We suggest that, awareness of intention tremor and ataxic gait in addition to mental retardation, peripheral neuropathy and early osteoporosis can be suspicious for CTX and lead diagnosis. Early treatment can provide stability and may also ameliorate existing neurological findings.

Long-term treatment effect in cerebrotendinous xanthomatosis depends on age at treatment start

Objective

To evaluate the effect of chenodeoxycholic acid treatment on disease progression in cerebrotendinous xanthomatosis (CTX).

Methods

In this retrospective cohort study, we report the clinical long-term follow-up characteristics of 56 Dutch patients with CTX. Age at diagnosis was correlated with clinical characteristics and with the course of modified Rankin Scale (mRS) and Expanded Disability Status Scale (EDSS) scores at follow-up.

Results

Median follow-up time was 8 years (6 months–31.5 years). Patients diagnosed and treated before the age of 24 years had a significantly better outcome at follow-up. When considering only patients with a good treatment adherence (n = 43), neurologic symptoms, if present, disappeared in all patients who were diagnosed before the age of 24 and treated since. Furthermore, treatment prevented the development of new neurologic symptoms during follow-up. In contrast, 61% of the patients diagnosed and treated after the age of 24 showed deterioration of the neurologic symptoms, with parkinsonism as a treatment-resistant feature. There was an improvement or stabilization in favor of patients diagnosed and treated before the age of 24 compared to those treated after the age of 24: 100% vs 58% for mRS scores and 100% vs 50% for EDSS scores, respectively.

Conclusions

Treatment start at an early age can reverse and even prevent the development of neurologic symptoms in CTX. This study emphasizes the importance of early diagnosis in CTX and provides a rationale to include CTX in newborn screening programs.

Movement disorders in cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is an inborn error of cholesterol and bile acid metabolism, leading to neuropsychiatric and systemic manifestations. Movement disorders have rarely been reported in CTX, while a detailed appreciation of the full phenotypic spectrum is required in order to prevent underdiagnosis of this disease. This review focuses on the frequency of more unusual, non-ataxia and non-spasticity movement disorders reported in CTX. In total, 39 articles were reviewed, describing 55 CTX patients with a movement disorder. Additionally, we report on seven patients with parkinsonism out of our Dutch cohort of 79 (77 genetically proven) CTX patients. Mean age at onset of the movement disorder was 40 ± 12 years (median 40, range 13-62 years). Movement disorders can be considered a late disease manifestation. Parkinsonism was the most frequently reported movement disorder, followed by dystonia, myoclonus and postural tremor. Movement disorders were found to be mixed in 23% of patients and were usually part of a complex clinical picture, rather than a prominent symptom. Still, in 18% of the cases, a movement disorder was the presenting symptom. Unusual movement disorders represent a rare clinical feature in CTX, but CTX should be considered in the differential diagnosis of these movement disorders, particularly in case of early onset, and when associated with other neurological features (especially cognitive impairment, pyramidal and cerebellar signs) and/or with systemic features (such as diarrhoea, cataract and tendon xanthomas). CTX is a treatable disorder, stressing the importance of considering CTX as a potential cause of movement disorders.

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.

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.

Context-dependent compensation among phosphatidylserine-recognition receptors

Phagocytes express multiple phosphatidylserine (PtdSer) receptors that recognize apoptotic cells. It is unknown whether these receptors are interchangeable or if they play unique roles during cell clearance. Loss of the PtdSer receptor Mertk is associated with apoptotic corpse accumulation in the testes and degeneration of photoreceptors in the eye. Both phenotypes are linked to impaired phagocytosis by specialized phagocytes: Sertoli cells and the retinal pigmented epithelium (RPE). Here, we overexpressed the PtdSer receptor BAI1 in mice lacking MerTK (Mertk -/- Bai1 Tg ) to evaluate PtdSer receptor compensation in vivo. While Bai1 overexpression rescues clearance of apoptotic germ cells in the testes of Mertk -/- mice it fails to enhance RPE phagocytosis or prevent photoreceptor degeneration. To determine why MerTK is critical to RPE function, we examined visual cycle intermediates and performed unbiased RNAseq analysis of RPE from Mertk +/+ and Mertk -/- mice. Prior to the onset of photoreceptor degeneration, Mertk -/- mice had less accumulation of retinyl esters and dysregulation of a striking array of genes, including genes related to phagocytosis, metabolism, and retinal disease in humans. Collectively, these experiments establish that not all phagocytic receptors are functionally equal, and that compensation among specific engulfment receptors is context and tissue dependent.

Epidemiology, diagnosis, and treatment of cerebrotendinous xanthomatosis (CTX)

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder of bile acid synthesis caused by mutations in the cytochrome P450 CYP27A1 gene that result in production of a defective sterol 27-hydroxylase enzyme. CTX is associated with abnormally high levels of cholestanol in the blood and accumulation of cholestanol and cholesterol in the brain, tendon xanthomas, and bile. Hallmark clinical manifestations of CTX include chronic diarrhea, bilateral cataracts, tendon xanthomas, and neurologic dysfunction. Although CTX is a rare disorder, it is thought to be underdiagnosed, as presenting signs and symptoms may be nonspecific with significant overlap with other more common conditions. There is marked variability in signs and symptoms, severity, and age of onset between patients. The disease course is progressive and potentially debilitating or fatal, particularly with respect to neurologic presentations that can include intellectual disability, autism, behavioral and psychiatric problems, and dementia, among others. Treatment with chenodeoxycholic acid (CDCA; chenodiol) is the current standard of care. CDCA can help restore normal sterol, bile acid, bile alcohol, and cholestanol levels. CDCA also appears to be generally effective in preventing adverse clinical manifestations of the disease from occurring or progressing if administered early enough. Improved screening and awareness of the condition may help facilitate early diagnosis and treatment.

Clinical and molecular genetic features of cerebrotendinous xanthomatosis patients in Chinese families

Cerebrotendinous xanthomatosis (CTX) is a lipid-storage disease caused by mutations in CYP27A1. Current publications of Chinese CTX were mainly based on case reports. Here we investigated the clinical manifestations, genetic features in Chinese CTX patients. The clinical materials of 4 Chinese CTX pedigrees were collected. The genetic testing was done by polymerase chain reaction plus Sanger sequencing. The features of Chinese CTX patients reported previously were also reviewed. Three novel mutations of p.Arg513Cys, c.1477-2A > C in family 1 and p.Arg188Stop in family 4 (NM 000784.3) in CYP27A1 were found. The probands in our study manifested cerebellar ataxia, tendon xanthoma and spastic paresis in family 1 and 4, tendon xanthoma plus spastic paraparesis in family 2, asymptomatic tendon xanthoma in family 3. Three known mutations of p.Arg137Gln, p.Arg127Trp and p.Arg405Gln were found respectively in Family 2, 3 and 4. For the Chinese patients reviewed, the most common findings were xanthomatosis (100%), pyramidal signs (100%), cerebellar ataxia (66.7%), cognitive impairment (66.7%), cataracts (50.0%), and peripheral neuropathy (33.3%). Chronic diarrhea was infrequently seen (5.6%). No mutation was found associated with any given clinical features. We identified 3 novel mutations in CYP27A1. In Chinese CTX patients, xanthomatosis was the most common symptom while cataracts and chronic diarrhea were less frequent. The special features in Chinese CTX patients might caused by the lack of serum cholestanol test and should be confirmed in larger number of patients in the future.

Cerebellar Disease Mimicking Cerebrotendinous Xanthomatosis: Langerhans Cell Histiocytosis

BACKGROUND

This report highlights the differential diagnosis of predominant cerebellar white matter abnormalities with dentate nuclei involvement.

PATIENT DESCRIPTION

We describe two individuals with Langerhans cell histiocytosis in whom the diagnosis of cerebrotendinous xanthomatosis was initially considered. The clinical picture consisted of a progressive cerebellar syndrome with typical magnetic resonance imaging abnormalities. In both individuals, the cerebellar syndrome preceded the diagnosis of Langerhans cell histiocytosis.

CONCLUSIONS

The magnetic resonance imaging abnormalities and neurological features in patients with Langerhans cell histiocytosis can be strikingly similar to those with cerebrotendinous xanthomatosis. In cerebrotendinous xanthomatosis, the cerebellar symptoms and cerebellar white matter abnormalities are usually seen in adult patients. In a pediatric patient with a cerebellar syndrome, showing these cerebellar white matter abnormalities a diagnosis of Langerhans cell histiocytosis is more likely.