Türker Duman

Frequency of mtDNA A1555G and A7445G mutations among children with prelingual deafness in Turkey

Considerable differences on the frequencies of the mitochondrial 12S rRNA A1555G and tRNASer(UCN) A7445G mutations have been reported in different populations. Our screening of 168 patients coming from independent Turkish families with prelingual sensorineural non-syndromic deafness revealed three deaf children with A1555G (1.8%) but no examples of A7445G. One proband with the mitochondrial A1555G mutation has also evidence for right parietal infarct on a brain imaging study, for which common thrombotic mutations were found to be negative. Conclusion: This study shows that the mitochondrial A1555G mutation is among the significant causes of prelingual non-syndromic deafness in the Turkish population.

A multistep process for the dispersal of a Y chromosomal lineage in the Mediterranean area

In this work we focus on a microsatellite-defined Y-chromosomal lineage (network 1.2) identified by us and reported in previous studies, whose geographic distribution and antiquity appear to be compatible with the Neolithic spread of farmers. Here, we set network 1.2 in the Y-chromosomal phylogenetic tree, date it with respect to other lineages associated with the same movements by other authors, examine its diversity by means of tri- and tetranucleotide loci and discuss the implications in reconstructing the spread of this group of chromosomes in the Mediterranean area. Our results define a tripartite phylogeny within HG 9 (Rosser et al. 2000), with the deepest branching defined by alleles T (Haplogroup Eu10) or G (Haplogroup Eu9) at M172 (Semino et al. 2000), and a subsequent branching within Eu9 defined by network 1.2. Population distributions of HG 9 and network 1.2 show that their occurrence in the surveyed area is not due to the spread of people from a single parental population but, rather, to a process punctuated by at least two phases. Our data identify the wide area of the Balkans, Aegean and Anatolia as the possible homeland harbouring the largest variation within network 1.2. The use of recently proposed tests based on the stepwise mutation model suggests that its spread was associated to a population expansion, with a high rate of male gene flow in the Turkish-Greek area.

Mutations of the 5alpha-steroid reductase type 2 gene in six Turkish patients from unrelated families and a large pedigree of an isolated Turkish village.

We describe six Turkish patients with 5alpha-steroid reductase type 2 deficiency from unrelated Turkish families and a large pedigree of one of these patients who reside north-west of Anatolia. Patients NA, KS, BD and SY presented for evaluation of bilateral inguinal masses with female phenotypes. Patient ABE had penoscrotal hypospadias with male phenotype. Homozygous mutation of the 5alphaSR2 gene was identified in five of these patients by genomic DNA analysis. These mutations were Leu55Gln in exon 1 (in patients FG, BD and ABE), deltaMet157 in exon 3 (in patient NA), and splice junction abnormality in intron 1 (in patient SY). One individual (patient KS) was found to be a compound heterozygous carrier of two different mutations, Leu55Gln in exon 1 and Arg171Ser in exon 3. Patient FG had a large pedigree with the Leu55Gln mutation in exon 1. The pedigree of this family with marital consanguinity is remarkable, and possibly due to the isolation of this family because of economic and social problems. A further 85 individuals belonging to this family were analyzed for exon 1 Leu55Gln mutations in the 5alphaSR2 gene. Forty-two of these 85 individuals (49.41%) had this alteration; 11 were homozygous (8 genetic male, 3 genetic female) and 31 heterozygous (18 genetic male, genetic female) for this mutation. It was interesting to see asymptomatic homozygous female carriers. In conclusion, according to our results and those of other Turkish patients reported by different investigators, 5aSR2 gene mutation analysis, especially for Leu55Gln in exon 1 and deltaMet157 in exon 3, must be carried out in Turkish patients with male pseudohermaphroditism. Homozygous asymptomatic female carriers must be taken into consideration in this clinical entity, especially in a closed population, because of the risk of transmitting the disease to their offspring.

Cytotoxic T lymphocyte-associated antigen-4 polymorphism in patients with rheumatic heart disease

Acute rheumatic fever (ARF) is a systemic inflammatory disease occurring as a consequence of an exaggerated immune response to group A, beta haemolytic streptococcal pharyngitis. The molecular mimicry between human target organs/tissues and specific components of the infectious organism leads to the development of autoimmune reactions and cardiac tissue damage in rheumatic heart disease (RHD). Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is a negative regulator of T cell activation and proliferation during the immune response. CTLA-4 gene polymorphism has been shown to affect the inhibitory function of CTLA-4. We aimed to analyze the association of CTLA-4 gene locus at position 49 of exon 1 with susceptibility to ARF/RHD. This study included a total of 98 patients with RHD as a sequela of ARF, who fulfilled the revised classification criteria of Jones and 154 healthy unrelated controls. CTLA-4 +49 A/G polymorphism was genotyped by using PCR-RLFP technique. Data was analyzed by binary logistic regression models. The frequencies of GG, GA and AA genotypes were found to be 14%, 47% and 39%, respectively, in patients and 6%, 45% and 49%, respectively, in controls. The GG genotype was found to be significantly different between patients and controls (OR: 3.11; P = 0.016). GA and AA genotypes did not statistically differ between patients and controls. Our data showed a significant association of +49G /G polymorphism in a small patient group with RHD.

The lack of genetic association of the Toll-like receptor 2 (TLR2) Arg753Gln and Arg677Trp polymorphisms with rheumatic heart disease.

Acute rheumatic fever (ARF) is a non-suppurative inflammatory disease after group A, β haemolytic streptococcal pharyngitis. Certain individuals can develop ARF. This finding implies variability in host predisposition to ARF. A variety of studies have linked specific genetic markers with ARF or rheumatic heart disease (RHD) as a sequelea of ARF. For this purpose, we aimed to search the role of polymorphisms in Toll-like receptor-2 and -4 (TLR2 and TLR4) gene in Turkish patients with RHD. This study included a total 84 patients with RHD, ages ranging between 18 and 65, 25 male and 59 female, fulfilling the revised classification criteria of Jones. One hundred forty healthy unrelated persons were selected as a control group. Genotype analysis: DNA was extracted from whole blood. TLR4 gene (Asp 299Gly and Thr399Ile) and TLR2 gene (Arg753Gln and Arg677Trp) polymorphisms were genotyped by the previously reported method. Statistical analysis: binary logistic regression models were used. Results were expressed as odds ratios (OR) with corresponding 95% confidence intervals (95% CI). Significant level was predefined at 0.05. There was a significant difference for carrying Ile allele in the 399 position in the patients compared to healthy controls (OR = 5.26, 95% CI, 1.40–19.73, p = 0.014). In the TLR4 gene, Asp 299Gly polymorphism did not reach to a statistically significant value (OR = 3.02). We found no Arg753Gln polymorphism of the TLR2 gene in the patient group. There were three heterozygote samples in the healthy group. We did not detect Arg677Trp polymorphism of the TLR2 gene in both patient and control groups.

Screening the SLC26A4 gene in probands with deafness and goiter (Pendred syndrome) ascertained from a large group of students of the schools for the deaf in Turkey

To the Editor: Pendred syndrome (PS) (OMIM no. 274600), initially described as deafness and goiter, has been reported as the most common form of syndromic hearing loss, with a prevalence of 4–10% among deaf probands (1). Mutations in the SLC26A4 gene, encoding for a chloride-iodide transporter protein, pendrin, are responsible for the syndrome (2, 3), as well as non-syndromic deafness associated with enlarged vestibular aqueduct (EVA) or Mondini dysplasia (4–6). Although two previous reports included two Turkish families with PS (7, 8), a systematic search for the frequency of this syndrome or mutation analysis in the Turkish population has not been reported before. The study was approved by the Ethics Committee at the Ankara University School of Medicine in 2001. We have visited residential schools in cities of Ankara, Amasya, Afyon, Denizli and Isparta; evaluated students for the presence of environmental causes of their hearing loss or syndromic forms of deafness using a standard questionnaire and physical examination form. Pedigrees of all students were also drawn and blood samples were obtained after informed consent forms were signed by parents. A total of 333 probands with pre-lingual-onset severe to profound sensorineural hearing loss (193 males and 140 females; ages ranging from 7 to 25 years), coming from reportedly independent 293 families, were included in the study after exclusion of students where unequivocal evidence was present for an environmental etiology. A palpable goiter was noted in 11 probands (3.3%) coming from eight independent families (3%). None of these students had been diagnosed with PS before. DNA was extracted from peripheral blood using the phenol-chloroform method. Co-segregation of the phenotype with microsatellite markers (D7S496, D7S2459, D7S3074, D7S2456) flanking the SLC26A4 gene within a 0.8-cM region was evaluated with denaturing polyacrylamide gel electrophoresis followed by silver staining. Mutation screening was performed for 21 exons and intron/exon boundaries using SSCP at 4 C followed by silver staining. Previously described primer pairs were used for PCR amplifications (9, 10). Samples with band changes were directly sequenced after cycle sequencing reactions using an automated sequencer (Beckman Coulter CEQ 2000). All samples were also screened and found to be negative for mutations in the GJB2 gene and for the A1555G mutation in the mtDNA with previously described protocols (11, 12). Characteristics of probands included in the screening are summarized in Table 1. In one family (A137), four sibs and a cousin had deafness and goiter (Fig. 1). All four affected siblings in this kindred had short stature, dry skin and hair, and coarse facies, which suggested early onset hypothyroidism. Two older brothers (A137-101 and 102) in this family were students of the school for the deaf and were on thyroid hormone replacement therapy because of hypothyroidism. Two younger siblings (A137103 and 104), however, were diagnosed as having hypothyroidism only after our screening. In the same small village where this family lives, two other families with non-syndromic hearing loss were identified. Questioning for the goiter or the clinical findings of hypothyroidism in other people of this village was negative. Microsatellite analyzes were suggestive of cosegregation of SLC26A4 with the phenotype in family A137 (Fig. 1). Although homozygosity for most of the markers was evident in other probands with parental consanguinity, there Clin Genet 2003: 64: 371–374 Copyright # Blackwell Munksgaard 2003 Printed inDenmark. All rights reserved CLINICALGENETICS ISSN 0009-9163

The α2 Gene Alleles of the Platelet Collagen Receptor Integrin α2β1 in Turkish Children with Cerebral Infarct

The possible role of point mutations in the platelet integrin α2β1 gene in Turkish children with ischemic stroke was evaluated in this study. The case-control study included 44 pediatric patients with cerebral infarct (age range, 10 months to 18 years) and 96 healthy unrelated individuals. Genotyping was performed according to previously described methods. Distribution of the three haplotypes were 36.4%, 45.3%, 10.4% and 31.8%, 50.0%, 13.6% for the controls and the patients, respectively. A new fourth haplotype was found which was 7.8% and 4.5% respectively. Our data indicated that these haplotypes are not risk factors in pediatric stroke group.

Kidney Transplantation in Immunologically High-Risk Patients

An increased number of sensitized patients await kidney transplantation (KTx). Sensitization has a major impact on patient mortality and morbidity due to prolonged waiting time and may preclude live donor transplantation. However, recent reports have shown that KTx can be performed successfully using novel immunosuppressive protocols. This study presents our experience with patients displaying donor-specific antibody (DSA) (+). We enrolled 5 lymphocyte cross-match (LCM) negative (complement-dependent cytotoxicity) and panel-reactive antibody (PRA) plus DSA-positive patients mean fluorescein intensity [MFI] > 1000) who underwent living kidney donor procedures. All subjects were females and their mean age was 36.7 years. In our protocol, we started mycophenolate mofetil (2 g/d), tacrolimus (0.01 mg/kg) and prednisolone (0.5 mg/kg) on day -6. We performed 2 sessions of total plasma exchange (TPE) with albumin replacement and administered 2 doses of IVIG (5 g/d). On day -1, we added rituximab (200 mg). On the operation day and on day +4, the patients received doses of basiliximab. Serum samples were taken on days -6, 0, and 30 as well as at 1 year after transplantation. All patients displayed immediate graft function. Mean basal DSA titer was 5624 MFI. After desensitization, the MFI titers decreased at the time of transplantation to 2753 MFI, and were 2564 MFI at the 1st month and 802 MFI at 1st year. Three patients experienced acute rejection episodes (60%). After treatment for rejection, the average follow-up was 17 months and last creatinine levels were 0.6-0.8 mg/dL (minimum-maximum). In conclusion, KTx can be succesfully performed in sensitized patients displaying DSA. However, there seems to be a greater acute rejection risk. There is no consensus regarding adequate doses of IVIG or plasmapheresis treatments; furthermore, more studies are needed to clarify the safe MFI titer of the DSA.

Serum interleukin-37 level and interleukin-37 gene polymorphism in patients with Behçet disease

Behçet’s disease (BD) is a chronic inflammatory disease. The etiopathogenesis of BD is not well understood and several cytokines and genetic factors have been investigated. Interleukin (IL)-37, which a member of IL-1 family is an anti-inflammatory cytokine. The aim of the study was to analyze serum IL-37 level and IL-37 gene polymorphisms to assess its possible role in BD. Two hundred twenty-three patients with BD and 80 healthy controls (HC) were enrolled. Serum IL-37 level was measured using an enzyme-linked immunosorbent assay (ELISA). Deoksiribo Nucleic acids (DNA) were extracted using a genomic DNA isolation kit. Single nucleotide polymorphism (SNP) of IL-37 gene (rs3811047) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) methods. Serum IL-37 level was not significantly different in BD and HC (p > 0.05). Serum IL-37 level was not associated with the disease activity (p > 0.05). However, its level was higher in mucocutaneous involvement compared with systemic involvement (p = 0.002) and HC (p = 0.005). IL-37 gene polymorphisms were similar in BD and HC (p > 0.05). IL-37 may play a role in the etiopathogenesis of BD by contributing to manifestation with more moderate clinical symptoms.