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Biomedical subjects

J Horst

Publications and source records attributed to J Horst.

At least 19 recordsLinked to original sources
PubMed2005

Complete cystic fibrosis transmembrane conductance regulator gene sequencing in patients with idiopathic chronic pancreatitis and controls.

BACKGROUND: Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene-many of which cause cystic fibrosis-have also been reported in patients with chronic pancreatitis. The authors examine whether mild or severe CFTR mutations, homozygous or compound heterozygous CFTR mutations, or even simple cystic fibrosis carrier status alone increases the risk of developing pancreatitis. METHODS: After exclusion of patients with trypsinogen (PRSS1) mutations, cystic fibrosis, or pulmonary disease, and with known risk factors for pancreatitis 67 patients with idiopathic chronic pancreatitis (ICP) from northwest Germany and 60 geographically and ethnically matched controls were recruited. The entire coding region of the CFTR gene was sequenced in all patients and controls. ICP patients were also analysed for serine protease inhibitor Kazal type 1 (SPINK1) gene mutations. RESULTS: Abnormal CFTR alleles were found to be twice as frequent in ICP patients as in controls (25/134 v 11/120; p<0.05). Three of four severe CFTR mutations detected in patients were compound heterozygous with another abnormal CFTR allele, whereas among controls three severe CFTR mutations were found in heterozygous cystic fibrosis carriers. In ICP patients 19 uncommon/mild mutations, including combinations of the 5T allele with 12TG repeats, were identified compared with only five in controls (p = 0.012). Heterozygous SPINK1 mutations were detected in eight ICP patients (15% v 1% in controls) but only one also carried an additional mild CFTR mutation. CONCLUSIONS: These data show that not only compound heterozygosity, but also cystic fibrosis carrier status for different types of CFTR mutations, including uncommon/mild mutations, significantly increase the risk of developing pancreatitis. Although 45% of the study's ICP patients carried predisposing genetic risk factors (for example, mutations in CFTR or SPINK1), the authors found no evidence that the risk conveyed by CFTR mutations depends on co-inherited SPINK1 mutations.

Adolescent↗
PubMed2001

Homologues to the first gene for autosomal dominant polycystic kidney disease are pseudogenes.

PKD1 is the first gene identified to be causative for the condition of autosomal dominant polycystic kidney disease. There are several genes homologous to PKD1 that are located proximal to the master gene on the same chromosome. Two of these genes have been recently covered in a large sequencing work on chromosome 16, and their structure has been broadly analyzed. However, the major question whether homologous genes (HG) code for functionally active polypeptides has not been resolved so far. The current study identifies and partially characterizes four more homologues of PKD1, different from the previously published sequence, two of which were found by screening of a BAC library and the other two contained in available databases. Analysis of HG transcripts shows that they are not translated in the model cell line T98G. Taken together, these findings suggest that homologues to PKD1 form a family of pseudogenes.

Base Sequence↗
PubMed2001

Spectrum of beta-thalassemia in Jordan: identification of two novel mutations.

Two hundred and forty-four beta-thalassemia alleles were identified from 135 unrelated occasionally and periodically transfusion dependent beta- and S/beta-thalassemia patients from all regions of Jordan. Allele identification was achieved by PCR amplification of beta-globin genes, dot-blotting the amplified DNA, hybridization with allele specific synthetic probes, and direct sequencing of amplified genomic DNA. A total of 19 different mutations were detected, eight of them constituted about 86% of the Jordanian thalassemic chromosomes. These mutations were IVS1-110 (G>A) (25%), IVS2-1 (G>A) (15%), IVS2-745 (C>G) (14.2%), IVS1-1 (G>A) (10%), IVS1-6 (T>C) (8.3%), codon 37 (G>A) (6.3%), codon 39 (C>T) (4.6%), and codon 5 (-C) (3.8%). The remaining eleven mutations were rare, presented with frequencies ranging between 0.4% and 1.6%. These included two novel mutations and four others detected in Jordan for the first time. The novel mutations were the frame shift (-C) at codon 49 and the substitution (A>C) at position -29 in the TATA box. Four alleles (1.6%) remained unidentified; having no abnormalities in their beta-globin gene sequences and therefore, constituted additional defects causing beta-thalassemia in the Jordanian population. These unknown alleles are expected to be candidates for upstream or downstream mutations affecting the expression of beta-globin gene. The results provided the essential foundation for planning a national preventive program for thalassemia in Jordan and will help improving the medical services for the patients and their families by helping their clinicians and genetic counselors in evaluating their variants and designing their treatment regimens.

Alleles↗
PubMed2001

Seven novel and four recurrent point mutations in the factor VIII (F8C) gene.

Haemophilia A is a X-linked bleeding disorder, caused by deficiency in the activity of coagulation factor VIII due to mutations in the corresponding gene. The most common defect in patients is an inversion of the factor VIII gene that accounts for nearly 45% of individuals with severe hemophilia A. Point mutations and small deletions/insertions are responsible for the majority of cases with moderate to mild clinical course and for half of the severe hemophilia A occurrences. The majority of these mutations are "private", because of the high mutation rate for this particular gene. We report on eleven pathological changes in the factor VIII sequence detected in male patients with haemophilia A or in female obligate carriers. Seven of these mutations are novel [E204N, E265X, M320T, F436C, S535C, N2129M and R2307P] and four have been previously identified [V162M, R527W, R1966X, and R2159C]. Genotype-phenotype correlations and computer prediction analysis on the effect of missense mutations on the secondary structure of the factor VIII protein are performed and the relationships evaluated.

DNA↗
PubMed2001

Spectral karyotyping and fluorescence in situ hybridization detect novel chromosomal aberrations, a recurring involvement of chromosome 21 and amplification of the MYC oncogene in acute myeloid leukaemia M2.

Recurring chromosomal aberrations are of aetiological, diagnostic, prognostic and therapeutic importance in acute myeloid leukaemia (AML). However, aberrations are detected in only two thirds of AML cases at diagnosis and recurrent balanced translocations in only 50%. Spectral karyotyping (SKY) enables simultaneous visualization of all human chromosomes in different colours, facilitating the comprehensive evaluation of chromosomal abnormalities. Therefore, SKY was used to characterize 37 cases of newly diagnosed AML-M2, previously analysed using G-banding. In 15/23 patients it was possible to obtain metaphases from viably frozen cells; in 22 additional cases, fixed-cell suspensions were used. Of the 70 chromosomal aberrations identified by SKY, 30 aberrations were detected for the first time, 18 aberrations were redefined and 22 were confirmed. SKY detected two reciprocal translocations, t(X;3) and t(11;19). In five cases, eight structural aberrations resulted in partial gains of chromosome 21, six of which were undetected by G-banding. In 4/5 cases, these resulted in copy number increases for AML1. Amplification of MYC was detected in three cases. Using SKY and FISH, clonal aberrations were identified in 5/18 cases with a presumed normal karyotype; 3/5 aberrations were of known unfavourable prognostic significance. Karyotypes were entered into a custom-designed SKY database, which will be integrated with other cytogenetic and genomic databases.

Chromosome Aberrations↗
PubMed2001

Low-level sex chromosome mosaicism in female partners of couples undergoing ICSI therapy does not significantly affect treatment outcome.

BACKGROUND: There is an increased rate of chromosomal anomalies, in particular low-level sex chromosome mosaicism, in the female partners of couples undergoing intracytoplasmic sperm injection (ICSI). METHODS: Among 811 consecutive couples presenting for pre-ICSI chromosome analysis, chromosomal abnormalities were detected in 54 individuals, of which 26 were low-level sex chromosome mosaicism in the females. Attention was focused on the treatment course and outcome of ICSI in 20 couples with low-level sex chromosome mosaicism in the females actually embarking on ICSI treatment (group I, n = 38 ICSI treatment cycles). Applying a case-control design, each of the 20 couples was matched according to female age and source of spermatozoa to couples without a chromosomal abnormality in either of the partners (group II, n = 38 ICSI treatment cycles). RESULTS: No significant differences were found between the groups in ovarian response, fertilization rate and number of embryos transferred. Pregnancy rates, as well as implantation and abortion rates did not differ significantly between the groups. CONCLUSIONS: The data suggest that low-level sex chromosome mosaicism in females has no major effect on the course and outcome of ICSI.

Abortion, Spontaneous↗
PubMed2001

Angiotensin-converting enzyme activity and the ACE Alu polymorphism in autosomal dominant polycystic kidney disease.

BACKGROUND: Previous studies concerning Alu I/D polymorphism in the ACE gene and ADPKD severity have used the Alu genotypes as a representative of the true biological variable, namely ACE activity. However, wide individual and ethnic differences in the proportion of variance in ACE activity explained by the I/D genotype may have confounded these studies. This investigation examines the association between ADPKD severity and ACE in terms of plasma enzyme activity and I/D genotypes in individuals from three different countries. METHODS: Blood samples were collected from 307 ADPKD patients (116 Australian, 124 Bulgarian and 67 Polish) for determination of ACE activity levels and I/D genotypes. Chronic renal failure (CRF) was present in 117 patients and end-stage renal failure (ESRF) in 68 patients. RESULTS: ACE activity was related to the I/D genotype, showing a dosage effect of the D allele (P=0.006). The proportion of variance due to the Alu polymorphism was 14%. No difference in ACE activity and I/D genotype distribution was found between patients with CRF versus normal renal function (P=0.494; P=0.576) or between those with ESRF versus those without ESRF (P=0.872; P=0.825). No effect of the I/D genotype on age at development and progression to renal failure (CRF; ESRF) was detected in the overall group, and in subgroups based on ethnic origin, linkage status and sex. CONCLUSION: ACE is not likely to play a role as a determinant of ADPKD phenotype severity.

Adolescent↗
PubMed2000

The practical importance of pedigree analysis in women considering invasive prenatal diagnosis for advanced maternal age or abnormal serum screening tests.

Genetic counselling prior to prenatal diagnosis subserves several functions, one of them to put the planned prenatal test into the wider context of the personal and familial medical history. Even though considered a pivotal part of counselling, little is known about the informational yield and practical relevance of a comprehensive pre-test pedigree analysis. This is particularly true for patients who do not consider prenatal diagnosis for a specific heritable disorder with a high recurrence risk in the ongoing pregnancy, but for a moderate risk for conditions such as Down syndrome that mostly arise de novo. We analysed the informational yield of pedigree analysis for such patients through a retrospective analysis of 1356 consecutive genetic counselling sessions. All cases were referred for advanced maternal age or an abnormal result upon triple serum marker screening. 148 cases (10.9%) were classified as having a significant and previously unknown genetic or teratologic risk factor for the fetus that was uncovered through pedigree analysis. Of these cases, 55% could be recommended a specific prenatal test covering the previously unknown genetic risk factor.

Abnormalities, Drug-Induced↗
PubMed2000

Screening the 3' region of the polycystic kidney disease 1 (PKD1) gene in 41 Bulgarian and Australian kindreds reveals a prevalence of protein truncating mutations.

Screening for disease-causing mutations in the unique region of the polycystic kidney disease 1 (PKD1) gene was performed in 41 unrelated individuals with autosomal dominant polycystic kidney disease. Exons 34-41 and 43-46 were assayed using PCR amplification and SSCP analysis followed by direct sequencing of amplicons presenting variant SSCP patterns. We have identified seven disease-causing mutations of which five are novel [c.10634-10656del; c.11587delG; IVS37-10C>A; c.11669-11674del; c.13069-13070ins39] and two have been reported previously [Q4010X; Q4041X]. Defects in this part of the gene thus account for 17% of our group of patients. Five of the seven sequence alterations detected are protein-truncating which is in agreement with mutation screening data for this part of the gene by other groups. The two other mutations are in-frame deletions or insertions which could destroy important functional properties of polycystin 1. These findings suggest that the first step toward cyst formation in PKD1 patients is the loss of one functional copy of polycystin 1, which indirectly supports the "two-hit" model of cystogenesis where a second somatic mutation inactivating the normal allele is necessary to occur for development of the disease condition.

3' Untranslated Regions↗
PubMed2000

Screening for mutations in the peripheral myelin genes PMP22, MPZ and Cx32 (GJB1) in russian charcot-marie-tooth neuropathy patients; irina V. Mersiyanova, sookhrat M. Ismailov, alexandr V. Polyakov, elena L. Dadali, valeriy P. Fedotov, eva nelis, ann Lofgren, vincent timmerman, christine van broeckhoven, and oleg V. Evgrafov (Article was originally published in human mutation 15:340-347, 2000)

The authors wish to correct a mistake which occurred in the reporting of one of the mutations. The mutation in Cx32 Met34Lys is wrongly described as 100A>G. The correct description of the mutation should be 101T>A (Met34Lys).

Journal Article↗
PubMed2000

Diagnosis of haploidy and triploidy based on measurement of gene copy number by real-time PCR.

We report the development of a method for diagnosis of heterozygous deletions or duplications based on measurement of gene copy number. The method involves amplifications of a test locus with unknown copy number and a reference locus with known copy number using real-time PCR. Progress of the PCR reactions is monitored using fluorigenic probes and a real-time fluorescence detection system. For each reaction, the number of cycles is measured at which a defined threshold fluorescence emission is reached. Using standard curves, the copy number of the test DNA relative to a common standard DNA is determined for each locus. From the ratio of the relative copy numbers, the genomic copy number of the test locus is determined. In order to demonstrate the accuracy and reliability of the method for genetic testing, we analyzed 43 patients with hereditary neuropathy with liability to pressure palsies (HNPP), containing a heterozygous deletion of a 1.5 Mb region on chromosome 17p11.2-p12, eight patients with Charcot-Marie-Tooth disease, containing a heterozygous duplication of the same genomic region, and 50 normal control individuals. As a test locus we analyzed the PMP22 gene located within the 1.5 Mb region. The genomic copy number of the test locus was precisely measured, and the presence or absence of the genomic deletion or duplication was unambiguously diagnosed in all individuals.

Charcot-Marie-Tooth Disease↗
PubMed2000

Seminal plasma characteristics as indicators of cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations in men with obstructive azoospermia.

OBJECTIVE: To determine the prognostic value of seminal plasma volume, pH, fructose, and alpha-glucosidase for the detection of cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations. DESIGN: Retrospective data analysis. SETTING: University infertility clinic (referral center). PATIENT(S): Fifty-nine men with obstructive azoospermia. INTERVENTION(S): Semen analysis including seminal plasma volume, pH, fructose, alpha-glucosidase, molecular genetic diagnosis of CFTR mutations and FSH measurement. MAIN OUTCOME MEASURE(S): Sensitivity and specificity of seminal plasma markers for the detection of CFTR mutations. RESULT(S): A CFTR mutation was detected in 26 of 59 patients with obstructive azoospermia. Patients carrying a mutation had significantly lower seminal plasma volume (mean +/- SEM: 1.5 +/- 1.4 mL vs. 2.8 +/- 2.2 mL), lower pH levels (25th percentile, median, 75th percentile: 6.5, 6.8, 7.5 vs. 7.7, 7. 9, 7.9) and lower fructose content (1.0, 1.1, 3.7 vs. 5.8, 20.0, 83. 0 micromol/ejaculate) than those without mutations. Diagnostic efficacy for detection of mutations was best (pH 81.4%, fructose 81. 8%) at a cutoff level for pH of 7.4 and fructose of 2 micromol/ejaculate. CONCLUSION(S): Seminal plasma markers provide an effective, noninvasive method to predict CFTR mutations in men with obstructive azoospermia.

Adolescent↗
PubMed2000

Clinical presentation and mutation identification in the NBS1 gene in a boy with Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder which belongs to the group of inherited chromosomal instability syndromes. The clinical characteristics include severe microcephaly, a dysmorphic facies, and immunodeficiency with predisposition to malignancies. While the cellular characteristics of ataxia teleangiectasia (AT) and NBS are similar, the clinical findings are quite distinct. NBS patients show characteristic microcephaly, which is rare in association with AT and they do not develop ataxia and teleangiectasia. Recently, the gene mutated in NBS has been identified. Here we report a 5-year-old Bosnian boy with severe microcephaly. Because of multiple structural aberrations involving chromosomes 7 and 14 typical for AT (MIM 208900) and NBS (MIM 251260), AT was diagnosed. We suggested the diagnosis of NBS because of the boy's remarkable microcephaly, his facial appearance, and the absence of ataxia and teleangiectasia. DNA analysis was performed and revealed that the boy is homozygous for the major mutation (657de15) in the NBS1 gene. This finding confirms the diagnosis of NBS in our patient and offers the possibility to perform a most reliable prenatal diagnosis in a further pregnancy.

Adult↗
PubMed2000

Clustering of male infertility in the families of couples treated with intracytoplasmic sperm injection.

Intracytoplasmic sperm injection (ICSI) is an effective treatment modality for male factor infertility, but it could promote the transgenerational transmission of genetic defects causing gametogenic failure. Cytogenetic and molecular techniques permit the diagnosis of some infertility-causing genetic aberrations, but many more probably evade detection with currently available technology. The analysis of the recurrence pattern of infertility in infertile couples' families could define the importance of heritable factors in the pathogenesis of human infertility. We have subjected 621 consecutive infertile couples treated with ICSI in a single institution to a comprehensive genetic workup including documentation of the family history, karyotyping and various DNA tests. In all, 1302 fertile couples served as controls. Of the infertile couples 6.4% were shown to have a fertility problem with a definite genetic basis. Male, but not female fertility problems displayed a distinct pattern of familial aggregation. In addition, the infertile couples had fewer siblings than the fertile controls, a finding compatible with suboptimal fertility already among the infertile couples' parents. In summary, our data indicate that male factor infertility should be considered a potentially heritable condition. The recurrence risk for infertility in the offspring of couples treated with ICSI might be substantial.

Adult↗
PubMed2000

Non-reproductive heritable disorders in infertile couples and their first degree relatives.

The genetic safety of intracytoplasmic sperm injection (ICSI) remains a matter of continuing debate. One source of concern is the limited knowledge about the general genetic constitution and background of patients who need sophisticated reproductive technology to procreate. It has been postulated that such individuals could be carriers of genetic lesions that might result in an increased prevalence of heritable disorders among their offspring. To investigate this issue, we determined the frequency of potentially heritable non-reproductive diseases in 621 infertile couples and their first degree relatives. A total of 1302 fertile couples who underwent genetic counselling prior to prenatal diagnosis served as controls. The infertile patients had a slightly higher prevalence of potentially heritable non-reproductive disorders ('significant genetic risk factors') than the controls (1. 9 versus 0.9%; P = 0.015). In contrast, such diseases were less prevalent in their families than in the fertile couples' families. Our data do not support the hypothesis that their familial genetic background predisposes children born after ICSI to malformations or other non-reproductive genetic diseases.

Adult↗
PubMed2000

No evidence for uniparental disomy of the sex chromosomes in idiopathic male infertility.

Uniparental disomy (UPD) is a rare genetic aberration characterized by the uni- rather than biparental inheritance of a pair of homologous chromosomes. Among the various adverse clinical effects that UPD can have in humans, abnormalities of the male reproductive system have been described in UPD of the chromosomes 7, 11, 14 and 15. Given the considerable rate of sex chromosomal aneuploidy in human gametes and zygotes, we postulated that paternal uniparental disomy of the sex chromosomes might be a cause of otherwise unexplained male infertility. With a set of highly polymorphic DNA markers the parental origin of the X chromosome in 41 men with severe idiopathic infertility was determined. In all patients the X chromosome was derived from the mother, indicating regular biparental inheritance of the sex chromosomes. We thus obtained no evidence that paternal uniparental disomy of the X and Y chromosomes is a mechanism underlying idiopathic male infertility.

Chromosome Aberrations↗