Trinucleotide repeat polymorphism at five disease loci in mixed Hungarian population

In apparently healthy, unrelated Hungarians we examined triplet repeat length polymorphism at Huntington disease (HD), spinal and bulbar muscular atrophy (SBMA), spinocerebellar ataxia type 1 (SCA-1), dentatorubral-pallidoluysian atrophy (DRPLA), and myotonic dystrophy (MD) loci. The distribution of alleles of the SCA-1 locus was markedly different compared with Asians and Caucasian samples examined by Watkins WS, Bamshad M, and Jorde LB [1995: Hum Mol Genet 4:1485-1491]. The unimodal distribution of peaks was shifted towards the shorter repeats on the average with 4-5 repeats. Alleles under 21 repeats at the SBMA locus were significantly less frequent in Hungarians than in Asians and Caucasians. We also found significant difference in the distribution of DRPLA allele size at repeat length over 15 repeats; these alleles were less frequent in Hungarians compared with Asians and Caucasians. No significant differences were found in alleles at the MD and also at the HD loci compared with the other groups. These findings suggest that these trinucleotide sites in combination with other markers are particularly useful for determination of the genetic origin of a population, if they can be compared with similar subset of data of other populations. The present results could not confirm the large genetic distance between Hungarian and Oriental races and the relatively short distance between Hungarian and other European populations suggested in earlier reports [Czeizel A, Benkmann H-G, Goedde HW, editors. 1991: Genetics of the Hungarian population. Budapest: Akadémiai Kiadó. p 82-334].

Cefetamet pivoxil treatment causes loss of carnitine reserves that can be prevented by exogenous carnitine administration

Two groups of pediatric patients receiving cefetamet pivoxil treatment (3 x 500 mg daily) for 7 days were studied. In the first group (Group A) the drug was administered alone; in the second group (Group B) the drug was given in combination with a molar excess of carnitine (3 x 1 g). Medication with cefetamet pivoxil alone was associated with a large urinary excretion of pivaloylcarnitine: Approximately 71% of the daily pivalate intake could be eliminated as carnitine ester in the urine. In this group, the plasma level and the urinary output of free carnitine decreased. By contrast, in Group B, the administration of molar excess of carnitine aided stochiometric elimination of pivalate as carnitine ester, and the plasma levels and carnitine-free urinary output were unchanged. The data show that medication of cefetamet pivoxil results in the formation of pivaloylcarnitine in children; the sustained loss of carnitine esters can ultimately lead to carnitine deficiency. Molar excess of exogenous carnitine aids in the elimination of pivalate derived from cefetamet pivoxil therapy and helps to maintain the carnitine reserves.

Muscle carnitine acetyltransferase and carnitine deficiency in a case of mitochondrial encephalomyopathy

Profound decrease of the carnitine acetyltransferase activity (0.08 U/g wet weight; 1.67% of control) and carnitine deficiency (total carnitine was 230 nmol/g wet weight in the patient vs 2730 in the controls) was detected in the skeletal muscle of a female paediatric patient. She died of her illness, which included cerebellar symptoms and slight muscle spasticity affecting mainly the lower extremities, at 1 year of age. Histological examination of the autopsy specimens revealed a selective Purkinje cell degeneration in the cerebellum: the cells had abnormal position, were shrunken and decreased in number, and displayed abnormal dendritic trees and fragmented, disorganized axons. Electron microscopy revealed mitochondrial abnormalities in skeletal and cardiac muscle and also in the Purkinje cells. Deletions of the mitochondrial DNA were detected in the muscle in heteroplasmic form (up to 7%). Mainly the ND4-ND4L region was affected, as evidenced by the PCR; however, other regions of the mitochondrial genome also showed deletions of varying size and extent, suggesting multiple deletions of the mitochondrial DNA.

Labeled trimethyllysine load depletes unlabeled carnitine in premature infants without evidence of incorporation

6-N-Trimethyl-[d9]-L-lysine (dTML), the labeled form of a mammalian carnitine precursor, was administered to two groups of premature infants. Although the urinary output of dTML significantly increased in the low-dose-treated group (100 micromol/day), this amount did not affect the urinary output or plasma levels of carnitine and carnitine esters. In the second group of infants, after administration of 500 micromol dTML the plasma-free carnitine concentration increased (from 9.95 +/- 0.63 to 12.9 +/- 0.87 nmol/ml, p > 0.05) with a significant increase in the urinary excretion of free carnitine on the day of dTML administration and on the posttreatment day (from 4.79 +/- 1.36 to 9.85 +/- 1.18 and to 17.5 +/- 2.31 micromol/day, respectively). Analysis of urine using fast atom bombardment mass spectrometry (FAB-MS) revealed only the presence of the dTML in the urine of the newborns; no change was detected in the relative abundance of any other carnitine precursor. Surprisingly, in the second group, which received the higher dose of dTML supplement, only the signal intensity of the unlabeled carnitine increased after dTML administration; no new peak appeared in the urine that would correspond to the de novo synthesized carnitine containing the stable isotope-labeled trimethyl group of dTML. Thus, the FAB-MS analysis clearly demonstrated that contrary to the likely prediction, the 270% extra free carnitine output was a consequence of a dose-dependent dTML-induced depletion of the free carnitine reserves from the newborns. The absence of the incorporation of the label from dTML into carnitine strongly suggests that circulating TML is not the precursor of carnitine in premature infants.

[Molecular biologic screening test (PCR) for fragile X syndrome]

Fragile X syndrome is the most common inherited from of familial mental retardation. It is caused by an expanded CGG repeat in the first exon of the fragile X mental retardation gene. A polymerase chain reaction based technique was used for the identification of full mutations among men. According to our conditions full mutations failed to amplify. An internal control was used at a CG rich region 147 bp upstream of the polymorphic region. The bands were visualised on silver stained polyacrylamide gels. From the 57 individuals studied molecular analysis was performed on 38 males and 16 females. From the 26 males with suspected fragile X syndrome 9 males resulted in no amplification of the 500 kb product, all having a positive cytogenetic result for fragile X syndrome. One cytogeneticly positive male had normal results by molecular studies suggesting a different mutation. All control males had normal results. The results on the 16 females studied were inconclusive. We suggest that our method is highly sensitive and specific for screening males for fragile X syndrome.

Phosphofructokinase interacts with molecular chaperonins GroEL and GroES

For studying the possible interaction between the chaperonins and phosphofructokinase (PFK), bacterial chaperonins GroEL, GroES, and the PFK were co-purified from chaperonin over-expressing, heat treated E. coli strains. GroEL interacted with PFK in the presence of Mg2+, leading to a gradual decrease in the activity of the enzyme. This type of GroEL-PFK interaction was overcame by the GroES. On the effect of the addition of ATP to the GroEL-PFK complex, the decreased activity of the enzyme was recovered suggesting release of the GroEL-bound enzyme. Contrary to this, in a complete refolding system containing GroEL, GroES, ATP and Mg2+, activity of heat treated bacterial PFK gradually increased showing, that GroEL and GroES together play a role in the folding and/or assembly of PFK. Similar effect of refolding system was also observed on rabbit muscle PFK. The data show that PFK can interact with GroEL, which results in binding of the enzyme; by contrast, GroEL and GroES together has a folding effect leading ultimately to increase of the activity of the enzyme.

[Diagnosis of Prader-Willi syndrome by reverse transcriptase polymerase chain reaction]

To approve Prader-Willi syndrome by molecular diagnostic assay, polymerase chain reaction of reverse-transcribed RNA was introduced by which indirect information can be gained on all known forms of the mutation. In this pilot study, 4 patients and 16 healthy control individuals were examined. Although the different mutation forms can not directly by identified by this approach, it is a useful and reliable test to confirm the clinical diagnosis of the Prader-Willi syndrome, and to screen for the syndrome in patients who present with only a few typical features.

[Incidence of factor V G1681A (Leiden) mutation in samplings from the Hungarian population]

Thromboembolic disorders affect 0.1% of the adult population. Two main groups of the underlying predisposition factors can be identified: environmental factors (e.g. dietary habits, physical activity, surgical interventions, pregnancy etc.) and several genetic predispositions (e.g. inherited anticoagulant defects). After the discovery of the genetic mutation of factor V, called Leiden mutation, it turned out, that this mutation is responsible for the development of resistance to activated protein C in majority of the cases. The importance of the Leiden mutation is further emphasised by population based investigations, which makes it the most frequent thrombosis risk factor known today. In our study we have identified 43 heterozygotes and 3 homozygotes with Leiden mutation in total of 665 samples. The 6.47% heterozigocy is in the range of earlier reports from Europe. The homozygote/heterozygote distribution deviated from the value predicted by the Hardy-Weinberg law.

[Mutation analysis in the CTG-base multiplication in a family with myotonic dystrophy in three generations]

A PCR-based method with a novel silver staining detection was developed for the determination of CTG repeat number in the 3' untranslated region of the MD-PK gene responsible for myotonic dystrophy. Through the investigation of a family with affected members in three generations the application of the method is presented. According to the results, healthy individuals were verified easily, and the repeat number in patients with mild features or with premutation could be determined accurately. In severe clinical forms, e.g. congenital myopathy, the expansion can be deduced only from the lack of amplification, however, this is also helpful if the segregation of familial alleles is known.

Autoantibodies against subunits of pyruvate dehydrogenase and citrate synthase in a case of paediatric biliary cirrhosis

In a newborn girl with a history of connatal liver damage, histological examination of a liver biopsy sample taken during the seventh week of life revealed incipient destruction of bile ducts. Very high titres of antimitochondrial antibodies were later detected in the plasma. As the hepatic injury tended towards fibrosis, the histological diagnosis became primary biliary cirrhosis. Autoantibodies against E1 alpha, E2, and E3 subunits and protein X component of pyruvate dehydrogenase complex, and against citrate synthase were detected on western immunoblotting in a 1 in 1000 dilution of the patient's serum. The patient died of her illness at 11 years of age. In liver specimens obtained at autopsy human immunoglobulin deposition was detected on the surface of almost all hepatic cells by immunohistology. As there is a physical and functional interaction between pyruvate dehydrogenase and citrate synthase within the mitochondria, the presence of autoantibodies against certain proteins in the patient suggests that in this form of the disease the molecular recognition and then the autoimmunisation process could be directed against a mitochondrial enzyme cluster containing both pyruvate dehydrogenase and citrate synthase.

[Androgen receptor gene (CAG)n of spinal and bulbar muscular atrophy found in the normal child population in Hungary]

A simple and accurate molecular biology method was developed for the diagnosis of the spinal and bulbar muscular atrophy. With this method DNA isolated from peripheral blood of 40 unaffected, apparently healthy children was assayed for the CAG repeat polymorphism responsible for the disease. The results were compared with population genetic studies of international references, and the data showed no differences between the Hungarian repeat length and findings of others. Our experience shows, that this method can be used for the differential diagnosis of muscular atrophies and praenatal diagnostics in affected families.

[Study of the Leiden mutation (factor VQ 506), the most frequent cause of thrombophilia, in 116 thrombosis patients]

The incidence of Leiden mutation was examined by PCR method in 116 thrombophilic patients in random fashion. Mean age at the first thrombotic episode was 30.97 years. 90 patients had positive family history for thrombosis, 67 had more than one thrombotic episodes. APC resistance with laboratory test was found in 51 cases (44%). F V Leiden mutation was proven in 44 patients (38%). 10 being homozygous and 34 heterozygous out of them.

Valproate treatment induces lipid globule accumulation with ultrastructural abnormalities of mitochondria in skeletal muscle

In skeletal muscle of seven children treated with valproic acid (VPA) microvesicular (0.05-2 microns) lipid droplets were observed between the myofibrils predominantly adjacent to the mitochondria. Most of the mitochondria showed ultrastructural abnormalities: several mitochondria were deformed and in several mitochondria abnormal configuration of cristae was observed. The size of some organelles reached the 10-20 microns length with normal diameter. The elongated mitochondria were located either in the long axis of the fibers or in the transverse direction near to the Z discs. In rats receiving valproic acid intraperitoneally for 14 days in daily dose of 100 mg/kg, steatosis developed in the liver, and focal lipid droplets could also be found in the skeletal muscle. The mitochondria of the rat liver appeared as normal, but in muscle the structure and organization of the cristae were disoriented. These observations show that treatment with valproate causes a kind of drug-induced mitochondrial cytopathy with microvesicular lipid deposition in the muscle. The lipid deposits are likely a result of the inhibited mitochondrial fatty acid oxidation. The formation of the abnormal mitochondrial structure could serve as background for the visible consequences of affected lipid metabolism.

Carnitine administration ameliorates the changes in energy metabolism caused by short-term pivampicillin medication

Ten children receiving pivampicillin for 8 days were studied. On the first 4 days the drug was given alone (4 x 500 mg/day), and on the last 4 days in combination with carnitine (4 x 1 g/day). Pivampicillin treatment was associated with formation and urinary excretion of pivaloylcarnitine and administration of carnitine aided the elimination of pivalate as its carnitine ester. The resting respiratory quotient increased from 0.86 +/- 0.01 to 0.96 +/- 0.01 on the 4th day of pivampicillin treatment. A shift was observed in the metabolic fuel consumption: a significant decrease was found in the amount of fats oxidized (0.31 +/- 0.17 vs 1.27 +/- 0.17 g x kg[-1] x 24 h[-1]). while the utilization of carbohydrates increased (6.20 +/- 0.51 vs 4.00 +/- 0.50 g kg[-1] x 24 h[-1]). Administration of carnitine decreased the respiratory quotient to 0.90 +/- 0.01 on the 8th day of treatment, consumption of fats increased, and the oxidation of carbohydrates decreased. The resting energy expenditure was not affected by the treatment.

CONCLUSION

Pivampicillin treatment results in inhibited oxidation of fats as metabolic fuel. This drug effect was partially reversed by carnitine which promotes the elimination of the pivaloyl moiety from the body.

[Molecular biologic study and the factor VIII gene in hemophilia A]

Results of inversion in the intron 22 region of the VIII factor gene studied by Southern blot are presented. Inversion was found in 20 of 46 patients. In 14 cases (70%) distal and in 6 cases (30%) proximal type of inversion was detected. The significance of the positive result in genetic counseling and in presymptomatic diagnosis of Haemophilia A is emphasized.

[Delta-F508 screening of infants at the Perinatal Intensive Care Center of the city if Pécs]

Cystic fibrosis (CF) is one of the most frequent (1:2500), potentially lethal autosomal recessive diseases among Caucasians. Molecular genetic examination has become the most valuable method used for diagnosis or population screening. 300 newborns treated in the Perinatal Intensive Care Unit were examined for the mutation delta F508. The results showed that the frequency of affected deltaF508 homozygotes was 1:100, which is significantly higher than found in the general population, but the frequency of carriers (1:33) is similar to the overall value.

Multiple mitochondrial DNA deletions and persistent hyperthermia in a patient with Brachmann-de Lange phenotype

In a newborn boy with characteristics of Brachmann-de Lange syndrome (BDLS) high temperatures were observed on the second day after birth and recurred 2-6 times daily during the 7 months of the patient's life. After transient hypertonia hypotonia developed. In muscle biopsy specimen taken on the 51st day of life, serious and progressive distortion of mitochondria was observed. In several mitochondria the cristae structure was broken, other mitochondria were shrunken and the damage progressed towards further deterioration in other organelles. At several points between the myofibrils amorphous material was seen possible debris of destroyed mitochondria. Most myofibrils seemed to be intact; however, in some areas myolytic signs were present. Analysis of the mitochondrial DNA (mtDNA) showed multiple deletions in skeletal and heart muscles, liver, lung and kidney. Since the mtDNA encodes several proteins of the respiratory complexes, the deleted mtDNA certainly affected the integrity of the mitochondrial oxidative phosphorylation process by synthesis of abnormal proteins. In the present case the hyperthermia may have been a result of the mtDNA damage.

Urinary glycosaminoglycan excretion in healthy and stone-forming children

Both in vivo and in vitro studies suggest that macromolecules excreted in the urine, e.g. glycosaminoglycans (GAGs) may be inhibitors of kidney stone formation. We evaluated urinary GAG excretion in 22 children with calcium oxalate stones [8 with absorptive hypercalciuria, 6 with renal hypercalciuria (RH), 8 with normocalciuria], and in 20 age-matched controls. There was no significant difference between the two groups in the total urinary GAG level. In terms of the various GAG fractions, patients with RH excreted considerably less keratan sulphate and considerably more dermatan sulphate than the other patients and healthy controls. There was no difference between the two groups in condroitin sulphate, heparan sulphate and hyaluronic acid excretion. We conclude that there is no significant correlation between the formation of calcium oxalate stones and urinary GAG excretion.

Vertebral anomalies in Larsen's syndrome

The case of two sisters with Larsen's syndrome is presented. In addition to typical features of the syndrome, "multiple coronal cleft vertebrae" of the lumbar vertebral bodies were seen in both sibs. The extremities were conspicuously short.

Generation of hydroxytrimethyllysine from trimethyllysine limits the carnitine biosynthesis in premature infants

epsilon-N-Trimethyl-L-lysine (TML) was given orally for 1 day to two groups of premature infants. There was no change in the output or plasma levels of carnitine at a dose of 100 mumol/day; however, the urinary TML increased 17-fold. In the second group, administration of 1 mmol TML increased the plasma levels and urinary output of carnitine; the output of TML increased 62-fold. During a search of the metabolites of carnitine biosynthesis by 1H NMR analysis of urine, only one new resonance (corresponding to the TML) could be identified in both groups. Fast atom bombardment mass spectrometry (FAB-MS) analysis of urine samples indicated an increase in TML in the treated patients; no changes were found in the relative abundance of any other precursors. These data show that a significant limitation of the conversion of hydroxy-TML to carnitine is not likely; rather, the conversion of TML to hydroxy-TML is regulatory in neonatal carnitine biosynthesis.

[Mitochondrial DNA deletion in hereditary cardio-encephalo-myopathy]

The case of a female patient with cardio-encephalo-myopathy who died of her illness at one year of age, similarly to her three sisters, is reported. In autopsy samples, like muscle, heart, liver and cerebellum activities of several mitochondrial enzymes were determined. In the skeletal muscle serious decrease of carnitine acetyltransferase was observed (from the normal 4.8 U/g to 0.08 U/g wet weight), while in other tissues this activity was normal. In the muscle activities of several other mitochondrial enzymes were also decreased (cytochrome oxidase, NADH cytochrome C oxidoreductase, citrate synthase), while in other tissues there were no similar changes. Serious distortion was observed in the structure of the majority of mitochondria of muscle and heart by electronmicroscopy. The number of the Purkinje-cells in the cerebellum decreased, and the cells were shrunken, their axons were fragmented and disoriented. Also the structure of the mitochondria was abnormal in the Purkinje-cells, while it was normal in other areas of the cerebrum. In te tissues of the patient normal and deleted mitochondrial DNA coexisted as which could explain the genetic background of this disease at molecular level.