The effect of parental age on NF1 patients in Turkey.

Neurofibromatosis type 1 (NF1) is the most common neurogenetic disorder worldwide, and its clinical presentations are highly variable. NF1 is caused by mutations in the NF1 gene, and 50% of NF1 cases are sporadic, which occur in the absence of a family history of the disease and usually result from a new mutation in the germline of a parent. Advanced paternal age may increase the risk for germinal NF1 mutations; however, some dominant conditions, including neurofibromatosis, have shown a lesser association with paternal age, although there are conflicting reports in the literature. We investigated the effects of paternal and maternal age in 241 NF1 patients (121 sporadic and 120 familial cases) who were seen in Hacettepe hospital, a reference center for genetic diseases in Turkey. For statistical analysis, Spearman's and Chi-square tests were used. In this study, we evaluated paternal and maternal age at birth in sporadic and familial cases of NF1. We also compared the effect of parental age on the appearance and coexistence of various NF1 symptoms. There were no significant statistical differences between paternal age and coexistence of the NF1 symptoms. However, a slightly negative correlation was observed between paternal age and the coexistence of NF1 symptoms in familial cases (p < 0.05). We did not find strong evidence for the effect of parental age on the clinical severity of NF1.

Reproductive decisions after prenatal diagnosis in neurofibromatosis type 1: importance of genetic counseling.

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders affecting approximately 1/3500 individuals in all ethnic groups. It is characterized by cutaneous and plexiform neurofibromas, café-au-lait spots, Lisch nodules, freckling in axillary and inguinal regions, optic gliomas and an increased risk of malignancy. The mutation rate of NF1 is one of the highest known for human disorders: approximately 50% of all affected individuals carry de novo mutations. Detection of disease causing mutations in the NF1 gene allows presymptomatic and prenatal diagnosis, but is complex and time-consuming due to the large size of the gene, the existence of pseudogenes, the lack of clustering of the mutations in a particular region of the gene, and the variability of clinical findings. Because the time for investigations in prenatal diagnosis is restricted, detection of disease-associated NF1 alleles is more rapid and useful especially for familial cases. Therefore, genetic diagnosis of NF1 is frequently performed by linkage analysis. In our laboratory, 37 families were characterized with this method, of which two requested prenatal diagnosis. One fetus was found to be under NF1 risk. However, parents elected to continue pregnancy: the child is now 2.5 years old and has NF1 features. The phenotypic variability and the absence of genotype-phenotype correlation create difficulties in reproductive decisions for NF1 families, underlining the importance of appropriate counseling and detailed discussion of possible outcomes before genetic testing of the fetus.

DNA diagnostic tests in Xp21 dystrophy families for prenatal diagnosis.

Duchenne and Becker muscular dystrophies are X-linked genetic disorders characterized by dystrophin gene defects. We have studied 250 families with Duchenne and Becker muscular dystrophies (D/BMD) by molecular genetic methods since 1992. Nineteen exons of the dystrophin gene were analyzed for deletion. In families with no deletion, linkage analysis was performed to follow the inheritance of mutant alleles in the affected families. Twenty of these families requested prenatal diagnosis. Six mothers were found to be non-carriers (99% accuracy), thus fetuses were examined in the remaining 14. Two fetuses were affected and terminated. We report our experience and our current clinical practice in providing prenatal studies for D/BMD.

Molecular deletion patterns in Turkish Duchenne and Becker muscular dystrophy patients.

The dystrophin gene deletion patterns of Duchenne/Becker dystrophy were investigated in 57 DMD, 7 BMD and 1 DMD-BMD intermediate muscular dystrophy patients. Deletions, analyzed by multiplex amplification of selected exons, were observed in 58% (38 cases) of the patients. It was found that exon 48 was the most frequently affected, while exon 44 was the least frequently affected. The number of deleted exons was variable, but single exon deletions were more frequent (41%) than larger deletions in our population and the great majority of deletions began distal to exon 44. The application of PCR to deletion analysis in D/BMD was found to be very useful in delineating the extent of the deletion in most of the cases (82%). It was seen that the frequency of deletion breakpoints in distal part of the dystrophin gene (exons 42-52) was detected in 64% of our cases. In our group, the frequency of deletion breakpoints in the same area of the dystrophin gene was between that of the French and the Finnish patients. The distribution of deletion breakpoints within the dystrophin gene of the Turkish population seems to have some differences from other populations. Deletion breakpoints were found to be clustered mainly in three separate regions covering introns 44, 45 and 50 within the central region of the dystrophin gene. Intron 44 was mostly 5' breakpoints but it was found not to be involved as 3' breakpoints. The correlation between phenotype and type of deletion agreed with the reading frame theory except for one DMD case.

Allele frequencies of Mp6D-9 and GATT markers in 32 Turkish cystic fibrosis families.

The allele frequency of GATT and Mp6D-9 markers was investigated in 32 cystic fibrosis (CF) families. The GATT6 allele was found to be significantly associated with the delta F508 mutation. The Mp6D-9 allele 2/GATT6 haplotype was the major haplotype of the mutant alleles. Further analysis of CF alleles for population-specific mutations is underway so that a more direct approach can be taken, especially for families seeking prenatal diagnosis.

Analysis of delta F508 mutation in cystic fibrosis pathology specimens.

Incidence of delta F508, a severe mutation of the CFTR gene is found to be 36.3% in paraffin block cystic fibrosis liver tissues. Samples are histologically grouped according to severity of pancreatic involvement. Two families where delta F508 was detected postmortem and who have no living children, will have the chance for a prenatal diagnosis in the future pregnancies.

An unusual case of Duchenne muscular dystrophy.

A 10-year-old boy with Duchenne muscular dystrophy (DMD), with quite unusual clinical data, is presented. He was unable to walk until age 6, walked only for 9 months and then became wheel-chair bound. No dystrophin was present on muscle biopsy sections and a large deletion was found in the dystrophin gene. The deletion encompassed the central high frequency deletion region of the gene. Early developmental milestones may be delayed in DMD, but patients usually start to walk around 2-3 years of age. A delay of the extent in this case is very unusual.

Mutation analysis in Turkish phenylketonuria patients.

Forty-four classical PKU patients have been screened for various mutations. The newly identified IVS 10 splicing mutation was found in 32% of the mutant alleles and comprises 74.5% of the mutations that could be typed: 261arg-gln (6.8%), 158arg-gly (2.3%), 252arg-trp (1.1%), 280glu-lys (-), and 272gly-stop (-) were the other mutations that were screened.

Deletion analysis of Duchenne muscular dystrophy.

DNA of 15 patients with Duchenne muscular dystrophy (DMD) were analyzed for deletions within the DMD gene by using recombinant DNA technology. Deletion frequency was 47 percent and six of the deletions occurred in the region of probe 7 + 8. Only one of the deletions was observed in the region of probe 9-7, and no deletions were found in the region of probe 30-1, 30-2 and 47-4 (5b + 6). The frequency of deletions found in the Turkish DMD patients corresponds to frequencies reported for other populations.

Frequency of the IVS-10nt546 mutation in 44 Turkish phenylketonuria patients.

The newly identified point mutation in intron 10 of the phenylalanine hydroxylase gene activates a cryptic splice site and results in an in-frame insertion of nine nucleotides between exons 10 and 11 of the processed transcript. This mutation is observed in association with haplotype 6 of phenylketonuria chromosomes. Since in Turkey, haplotype 6 is observed in 40 percent of mutant phenylketonuria alleles, the aim of this study was to establish the incidence of this particular mutation. Forty-four classical phenylketonuria patients were studied and the frequency of the intron 10 splicing mutation was determined to be 31 percent.

Prenatal diagnosis of cystic fibrosis in a Turkish family.

Prenatal diagnosis of cystic fibrosis (CF) was made in a Turkish family whose first born child was diagnosed at necropsy as having CF. Two consecutive pregnancies followed. The fetus of the second pregnancy was diagnosed as having CF by the microvillar enzyme assay and was aborted. The diagnosis was verified by the DNA polymerase chain reaction analysis using chorionic villi from the abortus. In the third pregnancy, amniocentesis was performed in the 17th week, and KM19 polymorphism linked to CF was used to assess the status of the fetus. Since the fetus was determined to be a carrier, the family was advised to continue with the pregnancy.

[Determination of the csf lactate concentration by LDH enzymes for the diagnosis of bacterial and viral meningitis]. / Bos laktik asit düzeyinin LDH enzimi ile saptanmasi ve sonuçlarin viral ve bakteriyel menenjit ayirimi için degerlendirilmesi.

Rapid and accurate diagnosis of bacterial infections is one of the aims of clinical microbiology. This especially true in bacterial meningitis, when delay in proper treatment can be harmful or even fatal. Because the currently used techniques such as Gram stain, culture and immunoelectrophoresis have serious limitations. We previously evaluated cerebrospinal fluid (CSF) lactate levels by analytic way. In this study, we evaluated the diagnostic utility of CSF lactate concentrations which are determined by the enzyme LDH.

[Synthetic peptide antigens for medical cell biology]. / Sentetikik peptidlerin antijen olarak kullanilmasi.

The research in cell biology and medical sciences have been advanced through the use of antibodies specifically reactive with cellular proteins. In addition to conventional polyclonal and monoclonal antibodies, a third type of antibodies has come wide spread use within the past five years. Synthetic peptide antigens have been shown to elicit antibodies that can react with full length protein containing that peptide. Such antibodies are directed against a specific region of the protein chosen in advance by the investigator and so have a predetermined specificity. In basic research, these antibodies are usefull in identifying the protein product to particular cells or subcellular organelles and purifying the protein by immunoaffinity chromatography techniques. In medicine, such antibodies may provide reagents for passive vaccination, antitoxin therapy and targetted immunotherapy of neoplasia.