Pharmacodynamic profiling in three patients with molybdenum cofactor deficiency type A reveals prolonged biological effects after withdrawal of cyclic pyranopterin monophosphate.

Molybdenum cofactor deficiency type A has successfully been treated in a small number of children with daily intravenous administration of cyclic pyranopterin monophosphate. Pharmacodynamic data for this novel treatment have not been published and alternative dosing intervals have not been explored. We monitored pharmacodynamic biomarkers of sulfite oxidase and xanthine oxidoreductase activity in three patients with MoCD-A for a period of 2 to 9 months after discontinuation of cPMP substitution. We found that the clinical and metabolic effects were sustained for longer than expected, over 7 days at least. Our data implicate a biological half-life of the molybdenum cofactor dependent enzyme activities of approximately 3 days and suggest the possibility that less frequent than once daily dosing intervals could be a safe alternative to current practice.

Clinical onset and course, response to treatment and outcome in 24 patients with the cblE or cblG remethylation defect complemented by genetic and in vitro enzyme study data.

BACKGROUND: The cobalamin E (cblE) (MTRR, methionine synthase reductase) and cobalamin G (cblG) (MTR, methionine synthase) defects are rare inborn errors of cobalamin metabolism leading to impairment of the remethylation of homocysteine to methionine. METHODS: Information on clinical and laboratory data at initial full assessment and during the course of the disease, treatment, outcome and quality of life was obtained in a survey-based, retrospective study from physicians caring for patients with the CblE or CblG defect. In addition, data on enzyme studies in cultured skin fibroblasts and mutations in the MTRR and MTR gene were analysed. RESULTS: In 11 cblE and 13 cblG patients, failure to thrive, feeding problems, delayed milestones, muscular hypotonia, cognitive impairment and macrocytic anaemia were the most frequent symptoms. Delay in diagnosis depended on age at first symptom and clinical pattern at presentation and correlated significantly with impaired communication abilities at follow-up. Eighteen/22 patients presented with brain atrophy or white matter disease. Biochemical response to treatment with variable combinations of betaine, cobalamin, folate was significant. The overall course was considered improving (n = 8) or stable (n = 15) in 96% of patients, however the average number of CNS symptoms per patient increased significantly over time and 16 of 23 patients were classified as developmentally delayed or severely handicapped. In vitro enzyme analysis data showed no correlation with outcome. Predominantly private mutations were detected and no genotype- phenotype correlations evident. CONCLUSIONS: The majority of patients with the cblE and cblG defect show limited clinical response to treatment and have neurocognitive impairment.

Homocystinuria patient and caregiver survey: experiences of diagnosis and patient satisfaction.

BACKGROUND: The main genetic causes of homocystinuria are cystathionine beta-synthase (CBS) deficiency and the remethylation defects. Many patients present in childhood but milder forms may present later in life. Some countries have newborn screening programs for the homocystinurias but these do not detect all patients. RESULTS: HCU Network Australia is one of the very few support groups for patients with homocystinurias. Here we report the results of its survey of 143 patients and caregivers from 22 countries, evaluating current diagnostic pathways and management for the homocystinurias. Most (110) of the responses related to patients with CBS deficiency. The diagnosis was made by newborn screening in 20% of patients and in 50% of the others within 1 year of the initial symptom but in 12.5% it took over 15 years. The delay was attributed mainly to ignorance of the disease. Physicians need to learn to measure homocysteine concentrations in children with neurodevelopmental problems, and in patients with heterogeneous symptoms such as thromboembolism, dislocation of the optic lens, haemolytic uraemic syndrome, and psychiatric disease. Even when the diagnosis is made, the way it is communicated is sometimes poor. Early-onset CBS deficiency usually requires a low-protein diet with amino acid supplements. More than a third of the participants reported problems with the availability or cost of treatment. Only half of the patients always took their amino acid mixture. In contrast, good adherence to the protein restriction was reported in 98% but 80% said it was hard, time-consuming and caused unhappiness. CONCLUSIONS: There is often a long delay in diagnosing the homocystinurias unless this is achieved by newborn screening; this survey also highlights problems with the availability and cost of treatment and the palatability of protein substitutes.

High cysteine diet reduces insulin resistance in SHR-CRP rats.

Increased plasma total cysteine (tCys) has been associated with obesity and metabolic syndrome in human and some animal studies but the underlying mechanisms remain unclear. In this study, we aimed at evaluating the effects of high cysteine diet administered to SHR-CRP transgenic rats, a model of metabolic syndrome and inflammation. SHR-CRP rats were fed either standard (3.2 g cystine/kg diet) or high cysteine diet (HCD, enriched with additional 4 g L-cysteine/kg diet). After 4 weeks, urine, plasma and tissue samples were collected and parameters of metabolic syndrome, sulfur metabolites and hepatic gene expression were evaluated. Rats on HCD exhibited similar body weights and weights of fat depots, reduced levels of serum insulin, and reduced oxidative stress in the liver. The HCD did not change concentrations of tCys in tissues and body fluids while taurine in tissues and body fluids, and urinary sulfate were significantly increased. In contrast, betaine levels were significantly reduced possibly compensating for taurine elevation. In summary, increased Cys intake did not induce obesity while it ameliorated insulin resistance in the SHR-CRP rats, possibly due to beneficial effects of accumulating taurine.

Ancient origin of the CTH alelle carrying the c.200C>T (p.T67I) variant in patients with cystathioninuria.

Hereditary cystathioninuria is due to mutations in the CTH gene that encodes for cystathionase, a pyridoxal-5'-phosphate (PLP) dependent enzyme. To date, mutations in this gene have been described in 10 unrelated cystathioninuric patients. Enzyme assays have showed that mutated cystathionase exhibits lower activity than controls. As cystathioninuria is usually accompanied by a wide variety of symptoms, it has been questioned whether it is a disease or just a biochemical finding not associated with the clinical picture of these patients. This is the first report of Spanish patients with cystathioninuria and mild to severe neurological symptoms in childhood. After oral pyridoxine therapy biochemical parameters have normalized but clinical amelioration was not evident. All patients were homozygotes for the c.200C>T (p.T67I) variant which is the most prevalent inactivating mutation in the CTH gene. To further investigate the history of the alleles carrying the c.200C>T transition in Europe, we also constructed the haplotypes on the CTH locus in our Spanish patients as well as in a clinical series of cystathioninuric patients from the Czech Republic harboring the same nucleotide change. We suggest that the CTH p.T67I substitution could have an ancient common origin, which probably occurred in the Neolithic Era and spread throughout Europe.

Mode-selective vibrational redistribution after spectrally selective N-H stretching mode excitation in intermolecular hydrogen bonds.

Mode-selective vibrational redistribution after spectrally selective excitation within the highly structured N-H stretching band of the 7-azaindole dimer was observed by subpicosecond infrared-pump/anti-Stokes Raman-probe spectroscopy. Measurements after relaxation of the N-H stretching vibration indicate ultrafast initial population transfer to vibrations with pronounced N-H bending character. From these modes energy is transferred to modes of frequencies below 1000 cm(-1) on a slower time scale of about 3 ps. Tuning the spectrally narrow infrared excitation to the different substructures of the N-H stretching band influences the distribution of populations between the fingerprint modes. Their relative populations are correlated with the contributions of the modes forming the different coupled combination tones of the N-H stretching band. These results provide experimental support to a Fermi resonance model previously used for simulations of the N-H stretching infrared absorption band shape and insight into relaxation from the initially excited combination bands.

Quality of analytical performance in inherited metabolic disorders: the role of ERNDIM.

External quality assurance (EQA) schemes are essential for improvement of accuracy, reliability and comparability of results of biochemical genetic tests. ERNDIM (European Research Network for evaluation and improvement of screening, Diagnosis and treatment of Inherited disorders of Metabolism), established in 1994, operates nine EQA schemes for biochemical genetic testing according to international norms and recommendations. These comprise qualitative schemes for amino acids, organic acids, purines and pyrimidines, special assays in serum and urine and white cell cystine, qualitative organic acid and acylcarnitine schemes, as well as diagnostic proficiency testing. The total number of participants has increased from 123 in 1994 to 268 in 2007. Additional activities include participation in the Eurogentest project, a laboratory directory, training, education and development of guidelines. Results from the quantitative amino acid scheme with 170 participants reveal good variation within and between laboratories of below 10% for 10 amino acids; good within-laboratory variation but intermediate inter-laboratory variation of 10-22% for 11 amino acids; and higher variation within and between laboratories for 8 amino acids. Results on samples from 51 inherited metabolic disorders from two of five centres organizing diagnostic proficiency testing indicate overall diagnostic efficiency above 80% and improved performance of individual laboratories. Comparison of results for 10 and 12 compounds in the serum and urine special assay schemes respectively for 2000 and 2007 reveal clear improvement of precision within laboratories and in inter-laboratory variation. There is considerable evidence that performance in biochemical genetic testing has improved since the introduction of ERNDIM schemes.

Genetically determined folate deficiency is associated with abnormal hepatic folate profiles in the spontaneously hypertensive rat.

Increased levels of plasma cysteine are associated with obesity and metabolic disturbances. Our recent genetic analyses in spontaneously hypertensive rats (SHR) revealed a mutated Folr1 (folate receptor 1) as the quantitative trait gene associated with diminished renal Folr1 expression, lower plasma folate levels, hypercysteinemia, hyperhomocysteinemia and metabolic disturbances. To further analyse the effects of the Folr1 gene expression on folate metabolism, we used mass spectrometry to quantify folate profiles in the plasma and liver of an SHR-1 congenic strain, with wild type Folr1 allele on the SHR genetic background, and compared them with the SHR strain. In the plasma, concentration of 5-methyltetrahydrofolate (5mTHF) was significantly higher in SHR-1 congenic rats compared to SHR (60+/-6 vs. 42+/-2 nmol/l, P<0.01) and 5mTHF monoglutamate was the predominant form in both strains (>99 % of total folate). In the liver, SHR-1 congenic rats showed a significantly increased level of 5mTHF and decreased concentrations of dihydrofolate (DHF), tetrahydrofolate (THF) and formyl-THF when compared to the SHR strain. We also analysed the extent of folate glutamylation in the liver. Compared with the SHR strain, congenic wild-type Folr1 rats had significantly higher levels of 5mTHF monoglutamate. On the other hand, 5mTHF penta- and hexaglutamates were significantly higher in SHR when compared to SHR-1 rats. This inverse relationship of rat hepatic folate polyglutamate chain length and folate sufficiency was also true for other folate species. These results strongly indicate that the whole body homeostasis of folates is substantially impaired in SHR rats compared to the SHR-1 congenic strain and might be contributing to the associated metabolic disturbances observed in our previous studies.

Dissecting the role of Folr1 and Folh1 genes in the pathogenesis of metabolic syndrome in spontaneously hypertensive rats.

Increased levels of plasma cysteine predispose to obesity and metabolic disturbances. Our recent genetic analyses in spontaneously hypertensive rats (SHR) revealed mutated Folr1 (folate receptor 1) on chromosome 1 as a quantitative trait gene associated with reduced folate levels, hypercysteinemia and metabolic disturbances. The Folr1 gene is closely linked to the Folh1 (folate hydrolase 1) gene which codes for an enzyme involved in the hydrolysis of dietary polyglutamyl folates in the intestine. In the current study, we obtained evidence that Folh1 mRNA of the BN (Brown Norway) origin is weakly but significantly expressed in the small intestine. Next we analyzed the effects of the Folh1 alleles on folate and sulfur amino acid levels and consecutively on glucose and lipid metabolism using SHR-1 congenic sublines harboring either Folr1 BN and Folh1 SHR alleles or Folr1 SHR and Folh1 BN alleles. Both congenic sublines when compared to SHR controls, exhibited significantly reduced folate clearance and lower plasma cysteine and homocysteine levels which was associated with significantly decreased serum glucose and insulin concentrations and reduced adiposity. These results strongly suggest that, in addition to Folr1, the Folh1 gene also plays an important role in folate and sulfur amino acid levels and affects glucose and lipid metabolism in the rat.

Genetic determinants of folate status in Central Bohemia.

Although several genetic factors have been implicated as determinants of blood folate concentration in various populations, their effect on folate status in the Czech population has not yet been examined. We explored whether blood folate concentrations in healthy Czech population are associated with polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR), folate hydrolase 1 (FOLH1), reduced folate carrier (RFC), and folate receptor (FOLR1) genes. In a cross-sectional study of 591 control subjects we determined genotypes by PCR-RFLP or ARMS-PCR methods, and plasma and erythrocyte folates by MEIA. The effect of different genotypes on folate status was examined by non-parametric tests and by regression analysis. The prevalence of the MTHFR 677C>T, MTHFR 1298A>C, FOLH1 1561C>T, RFC 80G>A and FOLR1 480G>C variant alleles was 0.34, 0.33, 0.05, 0.44 and 0.00, respectively. Only the MTHFR 677C>T variant was significantly associated with plasma folate concentrations (median 14.7, 14.0 and 12.2 nmol/l for the CC, CT and TT genotypes, respectively). Our study showed that among the five studied allelic variants, only the 677C>T polymorphism in the MTHFR gene is a significant genetic determinant of plasma folate concentrations in Czech population.

Enzymatic diagnosis of homocystinuria by determination of cystathionine-ß-synthase activity in plasma using LC-MS/MS.

BACKGROUND: Cystathionine ß-synthase (CBS) is released into plasma from organs expressing this enzyme. Decreased plasma CBS activity has been demonstrated in CBS-deficient patients with 16 different genotypes. The aim of this study was to determine plasma CBS activity in patients carrying 11 additional genotypes using two LC-MS/MS methods. Patients and methods CBS activity was measured in EDTA or heparin plasma using either a previously described or a newly developed LC-MS/MS method optimized for analysis of the reaction product, 3,3-(2)H2-cystathionine, as its butyl ester derivative. We analyzed plasma samples from 26 CBS-deficient patients with known genotypes and 57 controls. RESULTS: We developed a new LC-MS/MS method for simple and sensitive determination of CBS activity. Plasma CBS activity was low (i.e., 0.001-0.036 of the multiples of median control values, MoM) in patients homozygous for the prevalent Hispanic mutation c.572C>T (p.T191M) but was highly elevated (2.95 MoM) in a single patient homozygous for the c.1330G>A (p.D444N) mutation. Patients with the remaining nine genotypes exhibited decreased activities (0.00-0.22 MoM), which did not overlap with the controls (0.29-2.10 MoM). CONCLUSIONS: The determination of CBS activity in plasma is a rapid and non-invasive procedure for detecting a subgroup of CBS-deficient patients with distinct genotypes.

Haplotyping of wild type and I278T alleles of the human cystathionine beta-synthase gene based on a cluster of novel SNPs in IVS12.

Homocystinuria is most frequently due to deficiency of cystathionine beta-synthase (CBS). We identified IVS12 as a polymorphism hot spot of the human CBS gene and report five novel single nucleotide polymorphisms (SNPs): g.13514G>A, g.13617A>G, g.13715C>T, g.13800G>A, and g.13904C>T. Analyzing 50 control DNA samples of unaffected and unrelated subjects of German origin the observed frequencies of heterozygosity were 0.02, 0.36, 0.18, 0.36, and 0.36, respectively. These polymorphic markers were combined into four distinct IVS12-haplotypes A1, A2, B1, and B2, revealing frequencies of 0.75, 0.01, 0.15, and 0.09, respectively, with an observed overall frequency of heterozygosity at 0.38. This haplotype system and the SNP c.699 were employed in the analysis of ten alleles affected by the most prevalent CBS mutation, c.833T>C (exon 8; I278T). We found that the I278T alleles segregate with at least two distinct haplotypes characterized by upstream and downstream polymorphic sites instead of sharing a common ancestral haplotype. This was a remarkable finding even in patients with very similar ethnic background. The novel haplotype system may facilitate future studies on the evolution of the CBS gene and might be suited for genotyping of families affected by homocystinuria.

Cystathionine beta-synthase deficiency in Central Europe: discrepancy between biochemical and molecular genetic screening for homocystinuric alleles.

Recent reports suggested that homocystinuria due to cystathionine beta-synthase (CBS) deficiency is a more common inborn error of metabolism than originally thought. In this study we compared the prevalence of homocystinuric alleles ascertained by two different approaches. First, the incidence of homocystinuria estimated by selective biochemical screening in the Czech and Slovak Republics was 1:349,000 (95% CI 1:208,000-1:641,000). The two most common pathogenic mutant alleles found subsequently in these patients, IVS11-2A>C and c.833T>C, had a calculated population prevalence of 0.00042 (95% CI 0.00031-0.00055) and 0.00018 (95% CI 0.00013-0.00023), respectively. Second, to examine the possible negative detection bias of mildly affected patients we determined the prevalence of these two pathogenic mutations in a sample of 1284 unselected newborns. Indeed, the observed prevalence of the c.833T>C allele (0.00195, 95% CI 0.00063-0.00454) was 11x higher than in the previous group suggesting that many homozygotes for the c.833T>C had not been diagnosed by selective biochemical screening. The IVS11-2A>C allele was not detected among 2,568 newborn CBS alleles. The estimated incidence of homocystinuria of 1:83,000, calculated in a combined model, suggests that selective biochemical screening may ascertain only approximately 25% of all homocystinuric patients. In conclusion, homocystinuria in Central Europe may be sufficiently common to consider sensitive newborn screening programs for this disease.

Facts and artefacts in mevalonic aciduria: development of a stable isotope dilution GCMS assay for mevalonic acid and its application to physiological fluids, tissue samples, prenatal diagnosis and carrier detection.

A stable isotope dilution assay using D3-mevalonic acid was developed and applied to the study of mevalonic aciduria. The method also appears to be suitable for the evaluation of different therapeutic regimens in patients with hypercholesterolemia. Mevalonic acid was isolated by liquid partition chromatography and quantified as the underivatized lactone by means of ammonia chemical ionization selected ion monitoring capillary gas chromatography-mass spectrometry. In heterozygotes there was significantly greater urinary excretion of mevalonic acid, while the range of enzymatic activity of mevalonate kinase showed an overlap with that of controls. The analysis of amniotic fluids of two pregnancies at risk for mevalonic aciduria showed a 3277-fold elevation as compared to controls in the first case, diagnostic of an affected fetus, and a normal value in the second one. Mevalonic acid concentration was much increased in tissues of the affected and aborted fetus. Concentrations ranged from 840 to 1120 mumol/kg in various tissues and were as high as 1810 mumol/kg in brain. Concentrations in control fetal tissues were approximately 1 mumol/kg.

Accumulation and impaired in vivo metabolism of di- and trihydroxycholestanoic acid in two patients.

Two patients with a suspected peroxisomal disorder on the basis of neurological, craniofacial, hepatological and other abnormalities were studied. The phenotype of both girls was remarkably similar from birth until age 1.5 yr. Detailed studies in plasma revealed normal plasma very-long-chain fatty acids but the presence of di- and trihydroxycholestanoic acids and the C29-dicarboxylic bile acid, all known to occur in plasma from Zellweger patients. These results suggest an isolated defect in the peroxisomal beta-oxidation of the side chains of the cholestanoic acids. Activation of trihydroxycholestanoic acid and beta-oxidation of trihydroxycholestanoyl-CoA, measured in a liver biopsy, were normal, however, as was the peroxisomal beta-oxidation of palmitate. Although the molecular defect remains unknown, the results stress the importance of performing multiple analyses in any patient suspected to suffer from a peroxisomal disorder and indicate that screening for peroxisomal disorders based upon analysis of only plasma very long chain fatty acids with or without analysis of erythrocyte plasmalogen levels, may be inadequate.

Methionine-loading test: evaluation of adverse effects and safety in an epidemiological study.

BACKGROUND: Methionine loading test is commonly used to detect hyperhomocysteinemia in patients with arteriosclerosis and other conditions. As administration of methionine causes endothelial dysfunction in laboratory examinations, we explored whether loading with this compound leads to clinically relevant adverse effects, especially in vasculature. METHODS AND RESULTS: When studying genetic factors in arteriosclerosis we recorded acute complications during a standard methionine loading test (with a dose of 100 mg/kg bw) and assessed a 30-day mortality in a group of 296 patients with coronary artery or peripheral arterial disease and in 591 controls. Acute complications were observed in 33% of the women and 16.5% of the men. For each sex, the patients and controls exhibited the same proportion of complications. The most common symptom, dizziness, was attributable to methionine loading. In addition, isolated sleepiness, nausea, polyuria and decreased or increased blood pressure were observed in part of the subjects. None of the 887 individuals died within the 30-day period following the test. CONCLUSION: Our study suggests that although standard loading with L-methionine frequently causes transitory complications impairing perception and vigilance, the test does not have serious adverse effects on vasculature and may be considered a safe procedure.

Folate supplementation prevents plasma homocysteine increase after fenofibrate therapy.

BACKGROUND: Homocysteine is associated with an increased risk of atherosclerosis. The administration of fibrates has been reported to significantly increase plasma homocysteine levels, a potentially adverse effect of fibrates. We investigated the hypothesis that concomitant treatment with fenofibrate and folic acid leads to a smaller increase in plasma total homocysteine levels than treatment with fenofibrate alone. METHODS: A randomized, open-label study compared the effect of micronized fenofibrate (200 mg daily) alone versus fenofibrate plus folic acid (10 mg every other day) on plasma homocysteine levels. Twenty-two patients with mixed hyperlipidemia participated. The 9-wk treatment period was preceded by a 4-wk wash-out period without hypolipidemic drugs. RESULTS: In patients treated with fenofibrate only, plasma homocysteine levels increased by 6.85 +/- 5.23 micromol/L (from 12.27 +/- 3.15 to 19.13 +/- 7.20 micromol/L); in patients treated with fenofibrate and folic acid, plasma homocysteine levels increased by 2.01 +/- 2.88 micromol/L (from 10.14 +/- 2.32 to 12.15 +/- 3.08 micromol/L). The difference in the homocysteine increase between the two groups was statistically significant at P = 0.014. CONCLUSIONS: Folic acid supplementation in patients treated with fenofibrate significantly reduced the increase in plasma homocysteine levels. More studies are needed to clarify whether amelioration of this side effect increases the clinical benefit of fibrates.

Statistical approaches for evaluation of genetic risk factor of peripheral arterial occlusive disease.

In the paper we show results of medical study from statistical point of view. The medical study was aimed to study genetic risk factors of peripheral arterial occlusive diseases in Czech population. Two genes, CBS and MTHFR were examined, as various genotypes of these genes are thought to have impact on amino thiols, who participate in variety of reactions in vasculature. Statistical part of the study was responsible for analysis and interpretation of collected data.

[Prenatal diagnosis of lysosomal enzymopathies in the Czech Republic]. / Prenatální diagnostika lysozomálních enzymopatií v Ceské Republice.

BACKGROUND: Prenatal diagnosisi represents the important fprm of prevention of the inherited metabolic diseases and its accessibility becomes the most effective assistance to involved families. The aim of the study was to introduce prenatal diagnosis of major inherited lysosomal disorders of the group of lipidoses, micopolysaccharidoses, glycoproteinoses, and mucolipidoses. METHODS AND RESULTS: Methodological approach is based on the activity estimation of the specific lysosomal hydrolases that are missing or inactive. Methods were extended by a set of supportive analyses, namely by ultrastructural identification of the lysosomal storage of the non-degraded substrate, DNA analysis showing mutation in the family or by biochemical analysis of the amniotic fluid. Uncultured cultured chorionic villi, cultured amniotic fluid cells yand samples of the amniotic fluid were examined. Altogether 17 pregnancies at risk for seven different lysosomal enzymopathies were followed: GM2 gangliosidosis (2 cases), Fabra disease (3 cases), Krabbe disease (1 case), Niemann-Pick disease type A (1 case), mucopolysaccharidosis I (5 cases), mucopolysaccharidosis II (4 cases), mucolipidosis II (I-cell disease) (1 case). Profound deficiency of enzyme activities (alpha-galactosidase A in fabry disease, galactocerebrosidase in Krabbe disease, alpha-iduronidase in mucopolysaccharidosis I) was identified in three pregnancies, which were terminated on the mother's decision. The diagnose was confirmed by the biochemical analysis of tissues of aborted foetuses. In two of them (Fabry disease, mucopolysaccharidosis I) ultrastructural sings of storage werw proved. In two cases the foetal heterozygote state was identified. In case at risk for Niemann-Pick disease type A, the diagnosis was confirmed also by DNA analysis. In the pregnancy at risk for Fabry disease, heterozygous state was confirmed indirectly according to the difference of alpha-galactosidase activities in cultured and uncultured cells. A set control values of enzyme activities in individual types of processed material (native and cultured chorionic villi, cultured amniocytes, and amniotic fluid supernatant) has been established. CONCLUSIONS: Inherited lysosomal enzymopathies represent important indication for prenatal diagnosis available now in our department. Condicio sine qua non is the biochemical or molecular genetic confirmation of diagnosis in the family involved.

[Clinical picture of homocystinuria with cystathionine beta-synthase deficiency in 19 Czech and Slovak patients]. / Klinický obraz homocystinurie z deficitu cystathionin beta-syntázy u devatenácti ceských a slovenských pacientu.

BACKGROUND: Homocystinuria due to cystathionine beta-synthase deficiency is an autosomal recessive disorder of methionine metabolism. It manifests with vascular, central nervous system and connective tissue disturbances, and phenotypically resembles Marfan's syndrome. We analysed the clinical course of homocystinuria in Czech and Slovak patients. METHODS AND RESULTS: The group of homocystinuric patients consisted of 19 individuals (12 males and 7 females) aged 5-32 years (average age 18 years), who were diagnosed between 1980 and 1999. The overall incidence of homocystinuria in the Czech and Slovak Republics was 1:287,000. The proportion of pyridoxine-responsive patients was 47%. The average follow-up period was 10 years (range 1 month to 19 years). The prevalence of the individual signs in the group was as follows: lens dislocation--95% of patients, progressive myopia--79%, marfanoid habitus--74%, kyfoscoliosis--68%, osteoporosis--63%, psychomotor retardation--58%, other neurologic symptomatology--58% and tromboembolism--21%. The average delay between the first sign of the disease and the time when the diagnosis was made was 4 years (range 1 to 14 years). At the time of diagnosis the average levels of metabolites in plasma were as follows: total homocysteine 348 mumol/l (range 211-536), free homocystine 70 mumol/l (range 0-203) and methionine 359 mumol/l (range 75-937). CONCLUSIONS: Both the clinical course of homocystinuria due to the cystathionine beta-synthase deficiency and its incidence in the Czech and Slovak Republics are similar to those in other populations. Since homocystinuria is a treatable disease, it should be included in the differential diagnosis of Marfan's syndrome, tromboembolism and severe psychomotor retardation.