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

Case Report: a novel CYP27A1 gene variant in a patient with cerebrotendinous xanthomatosis with unusual clinical findings

PURPOSE/AIM OF THE STUDY

Cerebrotendinous xanthomatosis is a disease with important clinical and molecular heterogeneity. CYP27A1 gene was described as the cause of these defects, with more than 50 mutations involved in the disease. The objective of this study was to carry out a genetic study and a clinical description of a patient with unusual clinical manifestation of the disease.

MATERIALS AND METHODS

DNA sequencing was used for the evaluation of CYP27A1 exon sequences and their intron/exon boundaries. Copy number variants were calculated using a method based on depth of sequencing coverage. In addition, the potential effects of the missense variants were analyzed, and an in-silico protein modeling tool was used. Finally, a patient case description was performed in order to evaluate patient phenotype according to genetic results.

RESULTS

Patient clinical features indicate the possible presence of a disease milder phenotype. When analyzing the CYP27A1 gene, patient presents a pathogenic variant (p.Arg474Trp) and a variant of unknown significance (p.Met130Ile) that causes a slight modification of the protein functional structure. This variant in homozygosis or double or compound heterozygosis together with other biallelic pathological mutations may be the cause of the clinical phenotype observed in the reported patient.

CONCLUSIONS

Clinical manifestations of cerebrotendinous xanthomatosis are heterogeneous, and sometimes wrongly suggest the presence of other diseases. Some patients seem to present an "incomplete" phenotype, which could be redefined as a variant of the disease with further studies. The evaluation of new mutations allows for earlier diagnosis and greater effectiveness in its treatment.

Ataxia in a Movement Disorders Outpatient Clinic: a Single-Center Experience in Turkey

The etiology may not be determined in patients with ataxia despite detailed evaluations. The aim of this study was to investigate the clinical and laboratory characteristics of a large cohort of patients with adult-onset ataxia of different etiologies, particularly, undetermined etiologies despite extensive clinical, genetic, laboratory, electrophysiological, and imaging investigations. The medical records of all patients diagnosed with ataxia of subacute-chronic onset between January 2011 and March 2021 were reviewed retrospectively. The records of patients with symptom onset after 16 years of age were included in the study. In all patients, clinical and demographic findings were noted. Etiologies were classified as acquired, hereditary, degenerative (multiple system atrophy-cerebellar, MSA-C), functional, and undetermined. During the study period, we determined 74 patients with ataxia and 59 (35 males) patients met the study criteria. The age range was 22-87 years. The etiologies were hereditary (n = 19), acquired (n = 14), MSA-C (n = 9), functional (n = 2), and undetermined (n = 15). The patients with hereditary etiologies and undetermined causes were significantly younger at admission and at symptom onset (p = 0.001 and p = 0.000). There was a significant delay until diagnosis in patients with hereditary etiologies compared to other etiologies. In acquired etiologies, axial findings (71.4%) were more prominent whereas extremity and axial findings were more common in patients with hereditary etiologies (83.3%, p = 0.030). There were systemic and radiological indicators such as hearing loss, juvenile cataract, or dentate hyperintensity in certain disorders. Hereditary etiologies are as common as acquired or degenerative etiologies in adults. However, they have an earlier onset and delayed diagnosis. Therefore, we should recognize the extracerebellar neurological, systemic, and neuroimaging findings.

Etiologic Puzzle of Coronary Artery Disease: How Important Is Genetic Component?

In the modern era, coronary artery disease (CAD) has become the most common form of heart disease and, due to the severity of its clinical manifestations and its acute complications, is a major cause of morbidity and mortality worldwide. The phenotypic variability of CAD is correlated with the complex etiology, multifactorial (caused by the interaction of genetic and environmental factors) but also monogenic. The purpose of this review is to present the genetic factors involved in the etiology of CAD and their relationship to the pathogenic mechanisms of the disease. Method: we analyzed data from the literature, starting with candidate gene-based association studies, then continuing with extensive association studies such as Genome-Wide Association Studies (GWAS) and Whole Exome Sequencing (WES). The results of these studies revealed that the number of genetic factors involved in CAD etiology is impressive. The identification of new genetic factors through GWASs offers new perspectives on understanding the complex pathophysiological mechanisms that determine CAD. In conclusion, deciphering the genetic architecture of CAD by extended genomic analysis (GWAS/WES) will establish new therapeutic targets and lead to the development of new treatments. The identification of individuals at high risk for CAD using polygenic risk scores (PRS) will allow early prophylactic measures and personalized therapy to improve their prognosis.

Analysis of CYP27A1 mutations in Han Chinese women with intrahepatic cholestasis of pregnancy

OBJECTIVE

To explore the cytochrome P450 family 27 subfamily A member 1 (CYP27A1) gene mutations in Chinese women with intrahepatic cholestasis of pregnancy (ICP) and the correlation between CYP27A gene mutations and BA (bile acid) level changes.

METHODS

In this study, the entire coding region of the CYP27A1 gene was sequenced in 151 Han Chinese women with ICP and 1029 matched samples, and the pathogenicity of identified CYP27A1 gene mutations was judged through evolutionary conservation analysis, computational analysis and protein structure modeling. Finally, we verified the relationship between gene mutations and total serum bile acid (TBA) and cholesterol (CHOL) levels through experiments in cell culture.

RESULTS

We identified five heterozygous CYP27A1 missense mutations in five ICP samples. Three online tools, Polyphen-2, MutationTaster and SIFT, predicted that the five CYP27A1 mutations were pathogenic. Furthermore, all five mutations caused marked protein structural changes. Experiments in cells showed that the intracellular and medium levels of TBA in the mutant groups were lower than those in the wild-type group, while the CHOL levels were higher in all mutants except for the R158H mutant.

CONCLUSIONS

CYP27A1 mutations are associated with the levels of TBA and CHOL, suggesting that CYP27A1 mutations contribute to abnormal total cholesterol and BA levels, which leads to ICP.

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.

Patients with cerebrotendinous xanthomatosis diagnosed with diverse multisystem involvement

Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease caused by deficiency of sterol 27-hydroxylase enzyme encoded by CYP27A1 gene. This multicenter, cross-sectional descriptive study aimed to document clinical characteristics of CTX patients of different ages, clinical presentations of early-diagnosed patients, and responses to short-term chenodeoxycholic acid (CDCA) treatment. Seven of 11 CTX patients were diagnosed in childhood. Three patients (27%) had neonatal cholestasis, seven (63%) patients had a history of frequent watery defecation started in infantile period, and eight (72.7%) patients had juvenile cataract. Four patients in the adult age group had pyramidal signs and parkinsonism symptoms. The mean Mignarri score at diagnosis was significantly lower in the pediatric patients (267.8 ± 51.4) than in the adult patients (450.0 ± 64.0, p = 0.001). No significant difference was determined between pediatric patients and adult patients regarding plasma cholestanol concentration at diagnosis (p = 0.482). The frequency of defecation decreased with treatment in six children, who had diarrhea at admission. Compared to pretreatment values, patients' body weight and standardized body mass index significantly increased at the 12th month of treatment. In conclusion, Mignarri scores are lower in the pediatric patients than in adult patients since the most determinative signs of the CTX disease are not apparent yet in the childhood. The disease is frequently overlooked in routine practice as the disease presents itself with different clinical combinations both in adults and in children. CTX is potentially a treatable disease; thereby, enhanced awareness is critically important for early diagnosis particularly in children.

The clinical and imaging features of cerebrotendinous xanthomatosis: A case report and review of the literature

RATIONALE

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid deposition disorder characterized by systemic signs and neurological dysfunction. The radiological features of CTX are infrequently summarized in the literature.

PATIENT CONCERNS

We described a 40-year-old male patient who repeatedly engaged in wrestling matches and presented with progressive difficulty in walking and reduced balance with egg-sized, hard, smooth, and painless masses in both ankles.

DIAGNOSIS

Neuroimaging examination showed abnormalities both supra- and infratentorially. Bilateral ankle joint magnetic resonance imaging showed bilateral xanthomata of the Achilles tendon. The diagnosis was confirmed by the detection of a sterol 27-hydroxylase gene mutation.

INTERVENTIONS

The patient was treated with chenodeoxycholic acid (250 mg 3 times per day).

OUTCOMES

To date, the patient's bilateral xanthomas of the Achilles tendon have begun to diminish, and his neurological impairment has not deteriorated further but has not yet improved.

LESSONS

We report a rare case of CTX and summarize the clinical and imaging features of this disease. Our findings suggest that the abnormal signals in the dentate nucleus or a long spinal cord lesion involving the central and posterior cord, combined with tendon xanthoma, are important clues for the diagnosis of CTX.