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Urine samples and serum samples of a patient with cerebrotendinous xanthomatosis (CTX) were investigated by means of capillary gas chromatography, both before and during oral treatment with ursodeoxycholic acid (UDCA), and the results compared with those obtained during chenodeoxycholic acid (CDCA) therapy. The predominantly excreted bile alcohol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol and two abnormal bile acids, i.e. 23-norcholic acid and 23-hydroxycholic acid were determined. In addition, the serum cholestanol/cholesterol ratio was determined. Whereas previous experiments demonstrated that the urinary excretion of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol and the abnormal bile acids decreased within a few weeks during CDCA therapy, the present study shows that their urinary excretions remain essentially the same during UDCA treatment. In contrast to the decrease in the serum cholestanol/cholesterol ratio during CDCA therapy, this ratio remains essentially the same during UDCA therapy. It is therefore concluded that, in contrast to CDCA therapy, UDCA treatment is not effective in the treatment of CTX.

By means of capillary gas chromatography urine samples of patients with cerebrotendinous xanthomatosis (CTX) were investigated before and during treatment by oral administration of chenodeoxycholic acid. The occurrence of various conjugated bile alcohols, presumably glucuronides, was demonstrated, the major compound being 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23 xi, 25-pentol. In the bile acid fraction norcholic acid and hydroxycholic acid were shown to be present in considerable amounts. In this way the presence of CTX can be demonstrated conclusively. After chenodeoxycholic acid therapy the excretion of both abnormal bile acids as well as of bile alcohols rapidly decreased within a few weeks, showing the effectiveness of the treatment. By early discovery and subsequent therapy it may be possible to prevent the onset of the detrimental symptoms such as mental deficiency, caused by the accumulation of cholestanol and cholesterol in CTX patients.

The concentration ratios of cholestanol/cholesterol in biological materials (serum, cerebrospinal fluid and tendon biopsy) were determined using a capillary gas chromatographic method. The method was validated by gas chromatography-mass spectrometry. The ratio was determined in several groups of patients: (a) patients with cerebrotendinous xanthomatosis (in serum, cerebrospinal fluid and tendon biopsy), before and during chenodeoxycholic acid therapy, (b) patients receiving cholestyramine therapy (in serum), (c) patients suffering from various liver diseases (in serum) and (d) one patient before and after liver transplantation (in serum). It can be concluded that the cholestanol/cholesterol concentration ratio is a potentially useful parameter for monitoring liver diseases but is not specific for establishing the diagnosis of cerebrotendinous xanthomatosis.

The clinical features and additional investigations of 20 Dutch patients suffering from cerebrotendinous xanthomatosis (CTX), an inborn error of metabolism in bile acid synthesis, are described. The onset was in the second or third decade. The clinical picture at the time of examination consisted of a combination of two or more of the following signs: cataract, xanthoma of a tendon, mental deterioration, pyramidal tract signs, cerebellar signs and epilepsy. Mental retardation was reported in patients. CT-scanning showed cerebellar hypodensity in 8 out of 16 patients but this feature did not correlate well with cerebellar signs. The EEG was abnormal in all but one patient. Treatment with chenodeoxycholic acid resulted in a normalization of EEG and biochemical abnormalities but not of the clinical signs. Cholic acid was equally effective but had much less side effects. The importance of a diagnosis in early life is stressed as well as the examination of clinically unaffected heterozygous relatives.

Patients suffering from cerebrotendinous xanthomatosis, an inborn error of metabolism in bile acid synthesis, excrete excessive amounts of 23-hydroxylated bile alcohols, 23-norcholic acid and 23-hydroxycholic acid into urine. In this study the configuration of this excreted 23-hydroxycholic acid was established as (23R)-hydroxycholic acid. Urine samples of two treated patients, receiving chenodeoxycholic acid, were investigated to see whether this administered bile acid was partly converted into 23-hydroxychenodeoxycholic acid. One patient was treated with ursodeoxycholic acid for 1 month and subsequently with chenodeoxycholic acid, and the urinary excretion of both (23R)-hydroxychenodeoxycholic acid and (23R)-hydroxyursodeoxycholic acid were followed. Indeed, all three patients excreted (23R)-hydroxylated chenodeoxycholic acid during oral treatment with chenodeoxycholic acid, and the patient treated with ursodeoxycholic acid excreted (23R)-hydroxylated ursodeoxycholic acid. During treatment with chenodeoxycholic acid the excretion of (23R)-hydroxychenodeoxycholic acid increases at first and later on decreases markedly. These findings suggest increased (23R)-hydroxylase activity in patients suffering from cerebrotendinous xanthomatosis, acting both on endogenously synthesized bile alcohols and on exogenously administered bile acids; during continuation of chenodeoxycholic acid treatment in an effective dose (750 mg/day) this enzyme activity gradually disappears.

The urinary bile acid profile, obtained by capillary gas chromatography, of a patient suffering from cerebrotendinous xanthomatosis and treated with ursodeoxycholic acid demonstrated, besides the occurrence of 23-norcholic acid and (23R)-hydroxycholic acid (as a consequence of this disease), six additional unknown bile acids and three known bile acids, viz. ursodeoxycholic acid, hyocholic acid and omega-muricholic acid. The structure of two of the unknown bile acids were elucidated and proven by organic syntheses. These were 23-norursodeoxycholic acid and 3 beta-ursodeoxycholic acid. The structures of three bile acids were tentatively elucidated as being 1 beta-hydroxyursodeoxycholic acid, 21-hydroxyursodeoxycholic acid and 22-hydroxyursodeoxycholic acid, and the possibility that the structure of the remaining bile acid is that of 5-hydroxyursodeoxycholic acid is discussed. Two of these bile acids (1 beta-hydroxyursodeoxycholic acid and 5-hydroxyursodeoxycholic acid) also occurred in urine of a healthy individual during oral ursodeoxycholic acid treatment, whereas 23-norcholic acid, 23-norursodeoxycholic acid, (23R)-hydroxycholic acid, 21-hydroxyursodeoxycholic acid and 22-hydroxyursodeoxycholic acid were only present in urine of the patient suffering from cerebrotendinous xanthomatosis. The metabolism of ursodeoxycholic acid, both in the normal state and in the cerebrotendinous xanthomatosis, is discussed.

We used a commercial enzymatic kit for measuring 7 alpha-hydroxylated bile acids to screen urines from normal subjects, liver-transplant recipients, and patients with various liver diseases, cerebro-hepato-renal syndrome, or cerebrotendinous xanthomatosis (CTX). Because of their high concentrations of 7 alpha-hydroxylated compounds excreted, the CTX patients were clearly distinguished from all other groups except for a slight overlap with the patients with cerebro-hepato-renal syndrome and liver-transplant recipients. Gas chromatography for bile alcohols completed the differential diagnosis.

Patients suffering from cerebrotendinous xanthomatosis (an autosomal recessive inborn error of metabolism) can easily be distinguished from patients not suffering from this disease, as the first excrete large amounts of the bile alcohol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol, in urine, whereas the second do not. In order to find out, whether carriers of cerebrotendinous xanthomatosis can be detected in a biochemical way, we compared known carriers with controls. The urinary excretions of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol of both groups were practically absent and no selection of carriers with cerebrotendinous xanthomatosis could be made on that basis. When, however, carriers and non-carriers were subjected to cholestyramine treatment, by which endogenous bile acid synthesis was stimulated, the urinary excretion of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol in the carrier rose considerably, whereas this excretion remained essentially the same in the non-carriers. This test can be of value in the genetic counseling of carriers with cerebrotendinous xanthomatosis and helpful in the detection of newborn patients with cerebrotendinous xanthomatosis.

A patient is described with many clinical features of cerebrotendinous xanthomatosis (CTX), but with only slightly elevated cholestanol/cholesterol concentration ratios in serum and xanthomatous tissue. However, with capillary gas chromatographic determinations of urinary bile acids and bile alcohols we demonstrated the typical biochemical abnormalities as seen in CTX patients. This article emphasizes the value of urinary capillary gas chromatography as a specific test to establish the diagnosis of CTX and to monitor the biochemical effectivity of the different treatment regimens.

Patients suffering from cerebrotendinous xanthomatosis, an inborn error of metabolism in bile acid synthesis, were given oral treatment with chenodeoxycholic acid, ursodeoxycholic acid, cholic acid and taurocholic acid. The effectiveness of the different therapies was evaluated by measuring the urinary excretion of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol, which should decrease, when the administered bile acid is able to suppress endogenous bile acid synthesis. From the results it is concluded that chenodeoxycholic acid and cholic acid activate the bile acid negative feedback mechanism, contrary to ursodeoxycholic acid and taurine conjugated cholic acid. Either cholic acid or chenodeoxycholic acid are the therapies of choice for the treatment of cerebrotendinous xanthomatosis. For various reasons the use of cholic acid is especially recommended.

This study gives a review of the results obtained from biochemical investigations of 20 patients in The Netherlands suffering from cerebrotendinous xanthomatosis, an inborn error of metabolism in bile acid synthesis. Diagnosis can best be established by determining the excretion of urinary bile alcohols, in particular 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,23,25-pentol, in urine by means of capillary gas chromatography. Measurement of serum cholestanol levels or serum cholestanol/cholesterol ratios, commonly used for establishing cerebrotendinous xanthomatosis, are not reliable. The effectiveness of the different therapies, i.e. administration of bile acids, can be evaluated by monitoring the urinary excretion of bile alcohols. From such investigations it was concluded that cholic acid especially, but also chenodeoxycholic acid are the therapies of choice for the treatment of cerebrotendinous xanthomatosis. All patients, until now diagnosed in The Netherlands were not discovered before the third or fourth decade of life because the characteristic signs only then become manifest clearly. Unfortunately, because sterol storage is almost irreversible, therapy only results in minor improvements of the patient's condition. Therefore early detection of the presence of cerebrotendinous xanthomatosis is desirable so that treatment can start before extensive storage of sterols is a fact. We developed some laboratory assays with the purpose of early detection. One consists of the detection of cerebrotendinous xanthomatosis carriers by subjecting them to oral cholestyramine administration and monitoring the urinary excretion of the bile alcohol 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol before and after treatment. Secondly, a relatively simple screening test for cerebrotendinous xanthomatosis was developed based on an enzymatic assay of 7 alpha-hydroxylated steroids in urine. After suitable modification this assay in principle allows the screening of large populations for the existence of cerebrotendinous xanthomatosis and thus to detect the disease at an earlier stage of life.