Natural history of neurological abnormalities in cerebrotendinous xanthomatosis

Cerebrotendinous Xanthomatosis: Novel EEG finding of Fixation-Off Sensitivity

Cerebrotendinous Xanthomatosis (CTX) is a rare autosomal recessive condition resulting in accumulation of cholesterol and cholestanol due to disrupted bile synthesis. Affected tissues include brain, tendons, skin, bone, lungs, and eyes. We report a clinical case presenting with epilepsy, which has been described, however with a particular EEG appearance that appears novel with Fixation-Off Sensitivity (FOS). The patient's EEG showed significant buildup of abnormal slowing and frontally predominant generalized epileptiform discharges when her eyes were closed, and in contrast essentially normal tracings while eyes were open, eventually showing electrographic evolution and generating a bilateral tonic-clonic seizure. Genetic testing confirmed the diagnosis of CTX, and CTX-specific treatment with chonodeoxycholic acid was initiated in addition to anti-seizure medication.

Molecular dynamics, docking and quantum calculations reveal conformational changes influenced by CYP271A amino acid mutations related to cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid disorder caused by a deficiency in CYP27A1, the first enzyme in the bile acid biosynthesis pathway. CYP27A1 catalyzes the 7α-hydroxylation of cholesterol, playing an important role in cholesterol homeostasis. CTX leads to progressive neurological dysfunction, including cognitive impairment, epilepsy, peripheral neuropathy, and movement disorders. Missense mutations in CYP27A1 disrupt its activity, particularly at the heme binding region and the adrenodoxin-binding site. This study examined the structural effects of seven-point mutations in CYP27A1 using molecular dynamic (MD) simulations. Both mutant and wild-type (WT) proteins were modeled to observe their structural behavior. Additionally, by combining MD simulations, docking, and quantum calculations cholesterol binding was studied in WT and mutant proteins. Results indicated that mutations altered cholesterol binding mode, preventing it from adopting the correct position in the catalytic site. The substrate access channel in mutants became wider, shallower, or closed. The interaction between the isopropyl group of cholesterol and the heme was found to be crucial for the hydroxylation capacity of CYP27A1, as this interaction was only present in the cholesterol-WT complex.

Cognitive impairment in children and adults with cerebrotendinous xanthomatosis: A French cohort study

Cerebrotendinous xanthomatosis is a rare and treatable metabolic disorder related to the accumulation of cholestanol. This disorder is primarily associated with motor and cognitive impairments, although the latter has not been extensively characterized. The objectives of this work were to define the cognitive profile found in cerebrotendinous xanthomatosis patients, investigate the progression of cognitive impairment over time, and search for radio-clinical correlations. Through a multicentric chart review study, we collected cognitive and radiological data from nine children and eighteen adults with genetically proven cerebrotendinous xanthomatosis. We performed a volumetric and morphological analysis of the brain magnetic resonance imaging. In our cohort, 44% (4/9) of children and 78% (14/18) of adults exhibited cognitive impairment that can be severe. The study revealed a significant impairment in various cognitive domains, specifically executive, attentional, language, and visuo-spatial. Among adults, 16% (3/18) developed dementia after age 50. These three patients had delayed chenodeoxycholic acid treatment and important cerebral atrophy. Besides these three cases of late-onset cognitive decline, Mini-Mental State Evaluation was generally stable, suggesting cognitive impairment due to a neurodevelopmental disorder and persisting in adulthood. Cognitive impairment was less common in children, possibly related to early chenodeoxycholic acid treatment in our cohort. The severity of magnetic resonance imaging abnormalities did not predict cognitive impairment in patients. Overall, in cerebrotendinous xanthomatosis, cognitive impairment can be severe and mainly neurodevelopmental. Early chenodeoxycholic acid treatment might be associated with a reduced risk of cognitive decline.

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 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.

Disorders with prominent posterior fossa involvement

Inherited white matter disorders include a wide range of disorders of various origins with distinct genetic, pathophysiologic, and metabolic backgrounds. Although most of these diseases have nonspecific clinical and radiologic features, some display distinct clinical and/or imaging (magnetic resonance imaging, MRI) characteristics that might suggest the causative gene. Recent advances in genetic testing allow assessing gene panels that include several hundred genes; however, an MRI-based diagnostic approach is important to narrow the choice of candidate genes, particularly in countries where these techniques are not available. Indeed, white matter disorders with prominent posterior fossa involvement present specific MRI (and clinical) phenotypes that can directly orient the diagnosis. This chapter describes the main genetic disorders with posterior fossa involvement and discusses diagnostic strategies.

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.

Membrane Lipids in Ultra-High-Risk Patients: Potential Predictive Biomarkers of Conversion to Psychosis

Alterations in membrane lipids are reported in schizophrenia. However, no conclusion can be drawn regarding the extended and predictive value of these alterations in persons at ultra-high risk of psychosis (UHR). Recent studies suggested that sterols' impact on psychiatric disorders was underestimated. Here, we simultaneously explored sterols, fatty acids (FA), and phospholipids (PL) in UHR persons for the first time. We analysed erythrocyte membrane lipids in 61 UHR persons, including 29 who later converted to psychosis (UHR-C) and 32 who did not (UHC-NC). We used gas chromatography for FA and liquid chromatography tandem with mass spectrometry for sterols and phospholipids. Among UHR individuals, elevated baseline membrane linoleic acid level was associated with conversion to psychosis (26.1% vs. 60.5%, p = 0.02). Combining sterols, FA, and PL membrane composition improved the prediction of psychosis onset (AUC = 0.73). This is the first report showing that membrane sterol participates, with other membrane lipids, in modulating the risk of psychosis. It suggests that membrane lipids could be used as biomarkers for personalised medicine in UHR patients.

Balance impairment in cerebrotendinous xanthomatosis: Ankle strategy deficit. A case study

BACKGROUND

Cerebrotendinous xanthomatosis is a rare autosomal-recessive lipid storage disorder causing an elevation in cholestanol and cholesterol levels and their deposition in the central nervous system and tendons with consequent posture and gait disturbances.

METHODS

This report shows the case of a 36-year-old male affected by Cerebrotendinous xanthomatosis with static and dynamic instability. We aimed to provide an instrumented quantification of quiet upright standing using a piezoelectric force platform measuring the variations of center of pressure with the foot position 10 cm and 20 cm apart or extra-rotated with an opening angle of 30°, with eyes open or closed. The area of center of pressure and the length of its trajectory in the anterior-posterior and medial-lateral directions were computed. The temporal variability of center of pressure was evaluated by means of the Root Mean Square.

FINDINGS

In comparison with a control group, the area, the trajectory length of center of pressure in anterior-posterior and medial-lateral directions and the temporal variability increased in all static conditions. Intra-patient comparison showed that foot position 10 cm apart was the position that most influenced stability causing a marked worsening of area and trajectory length of center of pressure in both anterior-posterior and medial-lateral directions, particularly for the eyes closed condition.

INTERPRETATION

We found a large static instability due to internal neural and biomechanical constraints causing an insufficiency of ankle strategy. A physical therapy program based on instrumented proprioceptive exercises is to be implemented to teach the use of a hip strategy.

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.

Cerebrotendinous Xanthomatosis: A practice review of pathophysiology, diagnosis, and treatment

Cerebrotendinous Xanthomatosis represents a rare and underdiagnosed inherited neurometabolic disorder due to homozygous or compound heterozygous variants involving the CYP27A1 gene. This bile acid metabolism disorder represents a key potentially treatable neurogenetic condition due to the wide spectrum of neurological presentations in which it most commonly occurs. Cerebellar ataxia, peripheral neuropathy, spastic paraparesis, epilepsy, parkinsonism, cognitive decline, intellectual disability, and neuropsychiatric disturbances represent some of the most common neurological signs observed in this condition. Despite representing key features to increase diagnostic index suspicion, multisystemic involvement does not represent an obligatory feature and can also be under evaluated during diagnostic work-up. Chenodeoxycholic acid represents a well-known successful therapy for this inherited metabolic disease, however its unavailability in several contexts, high costs and common use in patients at late stages of disease course limit more favorable neurological outcomes for most individuals. This review article aims to discuss and highlight the most recent and updated knowledge regarding clinical, pathophysiological, neuroimaging, genetic and therapeutic aspects related to Cerebrotendinous Xanthomatosis.

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.

Follow‐up of 25 patients with treatable ataxia: A comprehensive case series study

Autosomal recessive cerebellar ataxias are a group of heterogeneous early‐onset progressive disorders that some of them are treatable. We performed a 4‐year follow‐up for 25 patients who had treatable ataxia. According to our study, patients would benefit from early detection of treatable ataxia, close observation, and follow‐up.

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.

Using fiber tractography and diffusion kurtosis imaging to evaluate neuroimaging changes in patients with cerebrotendinous xanthomatosis after stopping chenodeoxycholic acid treatment for three years

BACKGROUND

The aim of this study was to use tractography and diffusion kurtosis imaging (DKI) to evaluate cerebral white matter (WM) changes in patients with cerebrotendinous xanthomatosis (CTX) after stopping chenodeoxycholic acid (CDCA) treatment.

MATERIAL AND METHODS

Two siblings with CTX aged 40 and 38 years, respectively, who had been diagnosed with CTX for 16 years were enrolled. They had received CDCA treatment from 2005 until 2015, after which CDCA was no longer available in Taiwan. Serial brain magnetic resonance imaging (MRI) studies were used to record brain changes, and a series of neuropsychiatric tests were used to evaluate cognitive changes 3 years after stopping CDCA treatment.

RESULTS

The conventional MRI studies revealed progressive changes in dentate nuclei and surrounding cerebellar hemispheres, but no obvious changes in cerebral white matter (WM). Tractography captured in 2018 showed a general reduction in fiber density, especially involving frontal lobe fibers, compared to 2015. In addition, the DKI studies performed in 2018 showed a decreased axonal water fraction in diffuse WM structures and increased RadEAD in frontal WM. Comparisons of the neuropsychiatric test results between 2015 and 2018 showed a marked decline in executive function including design fluency, digit backward span and digit forward span, and this cognitive impairment highly suggested frontal lobe dysfunction.

CONCLUSIONS

This study may suggest that cerebral tractography and DKI study results can identify changes in cerebral WM in CTX patients shortly after stopping CDCA treatment, and that they may have a better correlation with the results of neuropsychiatric tests.

Genetic disease is a common cause of bilateral childhood cataract in Denmark

Purpose: Bilateral childhood cataracts can be caused by a metabolic disease, constitute a part of a syndrome, run in families, be sporadic or iatrogenic. The amount of work-up needed to establish a cause is discussed and the aim of the present study was to evaluate causes of bilateral childhood cataract.Methods: Chart review of 211 Danish children with bilateral cataracts. Information on work-up was retrieved with special focus on general health, metabolic screening, evaluation for congenital infections and genetic testing.Results: Cataract was seen in combination with systemic disease in 40.8%, 29.4% had hereditary cataracts, 27.0% had isolated cataract, in 1.4% it was associated with ocular malformations and 1.4% had been born prematurely without any other sequelae than the cataract. A genetic cause could be demonstrated in 74 children.Conclusion: Systemic comorbidities are very common in children with cataract and are not always known prior to the diagnosis of cataract. Genetic evaluation, especially targeted analyses, provided a molecular genetic diagnosis in a large proportion of those tested but it also failed to provide a molecular genetic diagnosis in some patients with a family history suggesting autosomal dominant inheritance. Most importantly, in some patients, genetic work-up provided a diagnosis in patients where it had therapeutic consequences and where the systemic disease would have caused irreversible damage, had it not been treated timely. Given the high prevalence of systemic disease, it seems advisable to co-manage children with bilateral cataracts with a pediatrician and to include genetic evaluation as part of the work-up.

Achilles Tendon Xanthoma and Cholestanol Revealing Cerebrotendinous Xanthomatosis: A New Case Report

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disease rarely reported in Africa. Therefore, we report a Moroccan first case report of CTX. A 20-year-old woman was presented in our department for bilateral swelling of the posterior aspect of ankles and the anterior aspect knees with gait disturbances evolving since the age of 7. The patient was the first child of consanguineous marriage. She had bilateral cataracts and developmental delay. Laboratory findings revealed that the plasma cholestanol level was remarkably elevated, and plasma and urine bile alcohol levels were elevated. MRI of ankles showed a bilateral diffuse thickening of the Achilles tendon with hypointense in T1 and heterogeneous hypersignal in T2 with spots in hypersignal in T1 and T2. Brain MRI revealed bilateral and symmetrical T2 hypersignal of dentate nuclei, without white matter signal alterations or cerebral or cerebellar atrophy. A biopsy obtained of the Achilles swelling with a histological study showed an aspect of tendon xanthoma. Hence, the diagnosis of CTX was made. MRI, especially brain MRI, plays an important role in the diagnosis of CTX.

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.

Update on cerebrotendinous xanthomatosis

PURPOSE OF REVIEW

Cerebrotendinous xanthomatosis (CTX) is a rare genetic lipid storage disorder with highly pleomorphic clinical phenotype. Complications of this disease can be devastating and may include severe cognitive impairment and dementia in later stages. Disease progression can be prevented or stabilized by bile acid replacement therapy, although a subset of patients with advanced disease continue to deteriorate despite therapy.

RECENT FINDINGS

Delayed diagnosis of CTX continues to impede effective treatment. A clinical diagnostic algorithm for CTX was developed that can decrease the age of diagnosis of CTX. The strategy of screening children with bilateral juvenile cataracts for CTX also improved diagnosis, as this group had a 500-fold higher-rate of CTX than the general population. Improved diagnosis of CTX is critical, as patients treated early in the course of the disease have significantly better outcomes compared with those treated later. More sensitive and specific biochemical testing for CTX has been developed that is potentially more informative than blood cholestanol to assess treatment efficacy and medication compliance in CTX.

SUMMARY

Because we are recognizing more severe presentations of CTX in infants and children, and delayed diagnosis and treatment worsens the prognosis, CTX is an excellent candidate disorder for newborn screening using recently reported methods for newborn dried bloodspot analysis.

Double trouble: a case of an ataxic young man with coeliac disease and cerebrotendinous xanthomatosis

We present the case of a 29-year-old south Asian man born of consanguineous marriage, presenting with ataxia, peripheral neuropathy and cognitive impairment. An initial diagnosis of coeliac disease was thought to explain the pertinent clinical features; however, further investigation led to an additional diagnosis of the rare yet treatable autosomal recessive condition, cerebrotendinous xanthomatosis. With both conditions employing highly diverse and overlapping clinical phenotypes, this contributed to a delay in diagnosis. Our report highlights the importance of paying close attention to both the clinical phenotype and family history.

Cerebrotendinous xanthomatosis-associated diarrhea and response to chenodeoxycholic acid treatment

BACKGROUND

In patients with cerebrotendinous xanthomatosis (CTX), chronic diarrhea is one of the earliest and main symptoms of the disease. In the current study, we evaluated the characteristics of the diarrhea and its response to chenodeoxycholic acid (CDCA) therapy in a cohort of Dutch CTX patients.

METHODS

We performed a retrospective review of medical records for 33 genetically confirmed CTX patients, and abstracted the characteristics of the diarrhea and the response to CDCA therapy (15 mg/kg/day up to 750 mg/day). The Bristol Stool Scale (BSS) was used for qualitative characterization of the stool.

RESULTS

Twenty-five patients had diarrhea documented at baseline (76%). Of these patients, 10 had diarrhea rated as 6 (fluffy pieces with ragged edges, a mushy stool), and 6 had diarrhea rated as 7 (watery, no solid pieces, entirely liquid) using the BSS. In 10 patients for whom data were recorded, the median stool frequency at baseline was 3 per day (range 2-6 per day). The response rate with CDCA for diarrhea resolution was 100% based on at least one post-baseline visit without diarrhea and 95% as assessed at the first post-baseline visit. In 68% of cases resolution was complete and sustained as no episodes of diarrhea were documented for follow-up periods as long as 25 years.

CONCLUSIONS

Chronic diarrhea persisting for years without spontaneous remission is a common feature of CTX at diagnosis. Chenodeoxycholic acid is an effective treatment for symptomatic relief of diarrhea in patients with CTX.

Patients with Lately Diagnosed Cerebrotendinous Xanthomatosis

Objectives: Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive inborn lipid storage disorder due to various pathogenic mutations in the CYP27A1 gene. Although the symptoms begin commonly in infancy, CTX diagnosis is often delayed. In this study, we report 7 Turkish CTX patients who had a delayed diagnosis despite early clinical signs and belonged to 6 unrelated families. Methods: We have retrospectively evaluated clinical, laboratory, imaging, and genetic findings of CTX patients, which were collected from 2 centers specialized in movement disorders: the Department of Neurology, Faculty of Medicine, Istanbul University, and the Department of Neurology, Faculty of Medicine, Mersin University. Results: All patients were diagnosed with CTX after neurological symptom development, and their mean age at diagnosis was 38.7 ± 9.6 years, despite a mean onset age of 12.4 ± 10.6 years. The mean follow-up period was 28 months (range: 3–60 months). The most common initial clinical abnormalities in our cohort were unexplained chronic diarrhea (42%), febrile convulsion (42%), juvenile cataract (85%), childhood depression and autism (14%), parkinsonism (14%), and intellectual disability (100%). The most prominent neurological findings were the pyramidal-cerebellar syndrome (85%) and extrapyramidal signs (42%). All patients were genetically confirmed. Serum cholestanol levels were elevated in all patients and decreased after chenodeoxycholic acid (CDCA) treatment in 6 patients. Conclusion: This cohort is the largest CTX case series in Turkey. All cases showed improvement in gastrointestinal symptoms as a response to CDCA treatment and stabilization on neurological symptoms, i.e., no further progression of neurological abnormalities were noted during this treatment. Therefore, early diagnosis and treatment is crucial in preventing clinical deterioration.

Lipids in the Physiopathology of Hereditary Spastic Paraplegias

Hereditary spastic paraplegias (HSP) are a group of neurodegenerative diseases sharing spasticity in lower limbs as common symptom. There is a large clinical variability in the presentation of patients, partly underlined by the large genetic heterogeneity, with more than 60 genes responsible for HSP. Despite this large heterogeneity, the proteins with known function are supposed to be involved in a limited number of cellular compartments such as shaping of the endoplasmic reticulum or endolysosomal function. Yet, it is difficult to understand why alteration of such different cellular compartments can lead to degeneration of the axons of cortical motor neurons. A common feature that has emerged over the last decade is the alteration of lipid metabolism in this group of pathologies. This was first revealed by the identification of mutations in genes encoding proteins that have or are supposed to have enzymatic activities on lipid substrates. However, it also appears that mutations in genes affecting endoplasmic reticulum, mitochondria, or endolysosome function can lead to changes in lipid distribution or metabolism. The aim of this review is to discuss the role of lipid metabolism alterations in the physiopathology of HSP, to evaluate how such alterations contribute to neurodegenerative phenotypes, and to understand how this knowledge can help develop therapeutic strategy for HSP.

Sterol 27-Hydroxylase Deficiency as a Cause of Neonatal Cholestasis: Report of 2 Cases and Review of the Literature

Introduction: Inborn errors of primary bile acid (BA) synthesis are rare autosomal recessive disorders responsible for 1-2% of cases of neonatal cholestasis. Among them, cerebrotendinous xanthomatosis (CTX) is caused by mutations in the CYP27A1 gene resulting in the impairment of sterol 27-hydroxylase enzyme activity. Patients and Methods: Here we present the study on two siblings with neonatal cholestasis diagnosed with sterol 27-hydroxylase deficiency. The clinical, biochemical, histological, and molecular presentation at the time of diagnosis and detailed follow-up were described. An extensive overview of the literature regarding patients with sterol 27-hydroxylase deficiency presenting with neonatal cholestasis was also provided. Results: Patient 1 presented with cholestatic jaundice since 10 weeks of age and developed the end-stage liver disease requiring liver transplantation at 8 months of age but finally succumbed 3 years post-transplantation due to autoimmune hemolytic anemia and multiorgan failure development. Next-generation sequencing performed post mortem, revealed him to be homozygous for the known pathogenic splicing variant c.1184+1G>A in the CYP27A1 gene. Patient 2 (sibling) presented with cholestatic jaundice since the first day of life. Sanger sequencing of CYP27A1 revealed the same results. Chenodeoxycholic acid treatment was introduced just after diagnosis, at 4 months of age. Fourteen patients with sterol 27-hydroxylase deficiency presenting with neonatal cholestasis were reported in the literature, in most of them presenting as a self-limiting disease. Conclusions: An early recognition and treatment initiation in CTX is essential.

The Classification of Autosomal Recessive Cerebellar Ataxias: a Consensus Statement from the Society for Research on the Cerebellum and Ataxias Task Force

There is currently no accepted classification of autosomal recessive cerebellar ataxias, a group of disorders characterized by important genetic heterogeneity and complex phenotypes. The objective of this task force was to build a consensus on the classification of autosomal recessive ataxias in order to develop a general approach to a patient presenting with ataxia, organize disorders according to clinical presentation, and define this field of research by identifying common pathogenic molecular mechanisms in these disorders. The work of this task force was based on a previously published systematic scoping review of the literature that identified autosomal recessive disorders characterized primarily by cerebellar motor dysfunction and cerebellar degeneration. The task force regrouped 12 international ataxia experts who decided on general orientation and specific issues. We identified 59 disorders that are classified as primary autosomal recessive cerebellar ataxias. For each of these disorders, we present geographical and ethnical specificities along with distinctive clinical and imagery features. These primary recessive ataxias were organized in a clinical and a pathophysiological classification, and we present a general clinical approach to the patient presenting with ataxia. We also identified a list of 48 complex multisystem disorders that are associated with ataxia and should be included in the differential diagnosis of autosomal recessive ataxias. This classification is the result of a consensus among a panel of international experts, and it promotes a unified understanding of autosomal recessive cerebellar disorders for clinicians and researchers.

Prevalence of Cerebrotendinous Xanthomatosis Among Patients Diagnosed With Acquired Juvenile-Onset Idiopathic Bilateral Cataracts

Importance

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive bile acid synthesis disorder caused by mutations in CYP27A1, the gene encoding sterol 27-hydroxylase, which results in elevated levels of plasma cholestanol and urinary bile alcohols. Clinical symptoms and signs may include early-onset chronic diarrhea, juvenile-onset bilateral cataracts, cholestatic jaundice, tendon xanthomas, and progressive neurological deterioration. Although initiation of treatment at a young age can prevent disease complications, diagnosis often occurs after the onset of permanent neurologic damage. Strategies are needed to facilitate early diagnosis.

Objective

To evaluate the prevalence of CTX in a patient population diagnosed with early-onset idiopathic bilateral cataracts.

Design, Setting, and Participants

This interim analysis of the Cerebrotendinous Xanthomatosis Prevalence Study was conducted in 26 active US sites from November 2015 to June 2017. The study included patients diagnosed as having idiopathic bilateral cataracts from ages 2 to 21 years. Potentially eligible study participants were identified through retrospective medical record review or on receiving care for cataracts at an active site. Data were analyzed from July 2017 to October 2018.

Main Outcomes and Measures

Measurement of plasma cholestanol levels and optional urine bile alcohol screening were performed. A plasma cholestanol concentration of 0.4 mg/dL or greater or a positive urine bile alcohol result prompted CYP27A1 genetic testing to confirm the diagnosis of CTX.

Results

Of 170 tested patients, 88 (51.8%) were male, and the median (range) age was 10 (2-49) years. A total of 3 patients (1.8%) had biochemical and genetic confirmation of newly diagnosed CTX (plasma cholestanol level greater than 1.0 mg/dL, positive urine bile alcohol result, and disease-causative mutations in CYP27A1). The mean (range) age at cataract diagnosis for patients with CTX was 12 (8-16) years. Reported symptoms included abnormal gait or balance (n = 3), learning disability (n = 2), cognitive decline (n = 2), seizures (n = 2), frequent bone fractures (n = 2), and chronic diarrhea (n = 1).

Conclusions and Relevance

To date, 1.8% of patients in this study were diagnosed as having CTX, which is approximately 500-fold the currently estimated prevalence of CTX in the general population (3 to 5 per 100 000). These data suggest that juvenile-onset idiopathic bilateral cataracts may be useful as a screening marker for CTX and that ophthalmologists can play an important role in facilitating early identification of this condition.

Clinical and molecular genetic features of cerebrotendinous xanthomatosis in Taiwan: Report of a novel CYP27A1 mutation and literature review

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disorder associated with mutations in the CYP27A1 gene, and the genetic features of CTX in Taiwanese have not been examined before.

OBJECTIVES

We report a new CTX family with a novel mutation in the CYP27A1 gene and analyze the clinical and molecular genetic features of CTX in Taiwan.

METHODS

The clinical and molecular genetic features of the two siblings from the new CTX family and the other 7 reported Taiwanese CTX patients were included for analysis. The clinical features of the enrolled CTX patients were recorded using the indicators that make up the suspicion index (SI).

RESULTS

The age at CTX diagnosis of the two siblings in the new CTX family were in late 30s, and predominantly psychiatric features. Both siblings had compound heterozygous splicing mutations in the CYP27A1 gene, including one mutation in exon 2 (c.435G>T, cryptic splice site) and one mutation in intron 7 (c.1264A>G, canonical splice site). None of the CTX patients in Taiwan were diagnosed during childhood or adolescence, and the most common clinical features of the 9 Taiwanese CTX patients were tendinous xanthomas, followed by ataxia and/or spastic paraparesis, dentate nuclei signal alternation at magnetic resonance imaging, intellectual disability and/or psychiatric disturbance, and polyneuropathy. Mutations in the CYP27A1 gene in the Taiwanese population were most commonly observed in exon 2, followed by exon 8 and intron 7. Except for one CTX patient who had an SI score of 100, the SI scores ranged from 300 to 400 before the study of the CYP27A1 gene and diagnosis.

CONCLUSIONS

We reported two Taiwanese CTX siblings who had compound heterozygous mutations in CYP27A1. Exons 2 and 8 and intron 7 are the hotspots for Taiwanese CTX mutations. The diagnosis of CTX in Taiwan is usually delayed and is probably under-recognized based on statistical estimations. Early identification and genetic diagnosis may be helpful to CTX patients because early treatment can reduce the accumulation of cholestanol and slow disease progression.

Evaluation of the effect of chenodeoxycholic acid treatment on skeletal system findings in patients with cerebrotendinous xanthomatosis

Aim:

The primary purpose of the present study is to evaluate the effect of chenodeoxycholic acid treatment on skeletal system findings in patients with cerebrotendinous xanthomatosis.

Material and Methods:

This retrospective study was conducted between June 2013 and December 2018 with seven patients with cerebrotendinous xanthomatosis in Cerrahpasa Medical Faculty Pediatric Nutrition and Metabolism Department. The clinical, epidemiologic, and genotypic features of the patients were reviewed in detail and the following items, especially related with skeletal system involvement, were recorded from medical data: history of a bone fracture, plasma calcium, phosphate, alkaline phosphatase and 25-hydroxy-vitamin D concentrations, bone mineral density values of the posteroanterior lumbar spine (L1-L4), and femoral neck before and after chenodeoxycholic acid treatment.

Results:

Regarding the bone mineral metabolism, plasma calcium, phosphate, alkaline phosphatase levels were found in normal ranges in all patients. Plasma 25-hydroxy-vitamin D evaluation at the time of diagnosis showed deficiency in three patients and insufficiency in three patients. Following chenodeoxycholic acid therapy, 25-hydroxy-vitamin D deficiency persisted in only one patient, but insufficiency was observed in four patients. According to the bone mineral density assessments, four patients had Z-scores below the expected range for age both at initial examination and after chenodeoxycholic acid therapy. No significant difference was observed between plasma 25-hydroxy-vitamin D levels and bone mineral density Z-scores before or after treatment.

Conclusion:

This study elucidates the necessity of additional medical treatment as a part of chenodeoxycholic acid therapy to improve skeletal system findings in cerebrotendinous xanthomatosis.

Diagnosis, treatment, and clinical outcomes in 43 cases with cerebrotendinous xanthomatosis

BACKGROUND

Cerebrotendinous xanthomatosis (CTX) is a rare disorder due to defective sterol 27-hydroxylase causing a lack of chenodeoxycholic acid (CDCA) production and high plasma cholestanol levels.

OBJECTIVES

Our objective was to review the diagnosis and treatment results in 43 CTX cases.

METHODS

We conducted a careful review of the diagnosis, laboratory values, treatment, and clinical course in 43 CTX cases.

RESULTS

The mean age at diagnosis was 32 years; the average follow-up was 8 years. Cases had the following conditions: 53% chronic diarrhea, 74% cognitive impairment, 70% premature cataracts, 77% tendon xanthomas, 81% neurologic disease, and 7% premature cardiovascular disease. The mean serum cholesterol concentration was 190 mg/dL; the mean plasma cholestanol level was 32 mg/L (normal <5.0 mg/L), which decreased to 6.0 mg/L (-81%) with CDCA therapy generally given as 250 mg orally 3 times daily. Of those tested on treatment, 63% achieved cholestanol levels of <5.0 mg/L; 91% had normal liver enzyme levels; none had significant liver problems after dose adjustment. Treatment improved symptoms in 57% at follow-up, but 20% with advanced disease continued to deteriorate. In the United States, CDCA has been approved for gallstone dissolution, but not for CTX despite long-term efficacy and safety data.

CONCLUSIONS

Health care providers seeing young patients with tendon xanthomas and relatively normal cholesterol levels, especially those with cataracts and learning problems, should consider the diagnosis of CTX so they can receive treatment. CDCA should receive regulatory approval to facilitate therapy for the prevention of the complications of the disease.