Emin Karaca

Functional consequences and structural interpretation of mutations of human choline acetyltransferase.

Choline acetyltransferase (ChAT; EC 2.3.1.6) catalyzes synthesis of acetylcholine from acetyl‐CoA (AcCoA) and choline in cholinergic neurons. Mutations in CHAT cause potentially lethal congenital myasthenic syndromes associated with episodic apnea (ChAT‐CMS). Here, we analyze the functional consequences of 12 missense and one nonsense mutations of CHAT in 11 patients. Nine of the mutations are novel. We examine expression of the recombinant missense mutants in Bosc 23 cells, determine their kinetic properties and thermal stability, and interpret the functional effects of 11 mutations in the context of the atomic structural model of human ChAT. Five mutations (p.Trp421Ser, p.Ser498Pro, p.Thr553Asn, p.Ala557Thr, and p.Ser572Trp) reduce enzyme expression to less than 50% of wild‐type. Mutations with severe kinetic effects are located in the active‐site tunnel (p.Met202Arg, p.Thr553Asn, and p.Ala557Thr) or adjacent to the substrate binding site (p.Ser572Trp), or exert their effect allosterically (p.Trp421Ser and p.Ile689Ser). Two mutations with milder kinetic effects (p.Val136Met and p.Ala235Thr) are also predicted to act allosterically. One mutation (p.Thr608Asn) below the nucleotide binding site of CoA enhances dissociation of AcCoA from the enzyme–substrate complex. Two mutations introducing a proline residue into an α‐helix (p.Ser498Pro and p.Ser704Pro) impair the thermal stability of ChAT. Hum Mutat 32:1259–1267, 2011. ©2011 Wiley Periodicals, Inc.

The phenotypic and molecular genetic spectrum of Alström syndrome in 44 Turkish kindreds and a literature review of Alström syndrome in Turkey.

Correction to: Journal of Human Genetics (2015) 60, 1–9; doi:10.1038/jhg.2014.85; published online 9 October 2014 Since the advance online publication of this article, the authors of the above paper have noticed errors in the list of authors and affiliations. Article with correct authors informationnow appears in this issue.

Evaluation of telomerase mRNA (hTERT) in childhood acute leukemia

Human telomerase reverse transcriptase (hTERT) is the catalytic component of telomerase enzyme and has been shown to be associated with telomerase activity (TA). Although many studies in adult leukemia have established the importance of TA, very few have been reported in the children. In this study hTERT levels in childhood leukemia was evaluated and compared with the prognostic factors described before. The LightCycler instrument was used (online real-time PCR) for the quantification of hTERT in peripheral blood and bone marrow in 23 cases with acute lymphoblastic leukemia (ALL) and in 8 cases with acute myeloblastic leukemia (AML). Ten cases with normal peripheral blood (PB) and bone marrow (BM) were selected as control group. Cytogenetic analyses were available in 21 patients with leukemia. In all cases with acute leukemia and in control group, peripheral blood (PB) hTERT levels correlated significantly with bone marrow (BM) hTERT levels. Before treatment, patients with ALL had significantly higher hTERT levels than that of AML patients and control cases. Among patients with ALL, higher hTERT levels were observed in patients with pre-B leukemia, followed by B cell and T cell leukemia patients. Initially increased hTERT levels decreased to the nearly normal levels during remission in cases with ALL. No correlation was observed between the initial hTERT levels and the known prognostic factors except cytogenetic findings. Higher hTERT levels were detected in patients having karyotypic abnormalities which indicate poor prognosis. hTERT levels are significantly high in childhood ALL with the highest level of pre-B cell leukemia before treatment. Those high levels of hTERT decrease to almost normal levels in remission. hTERT levels might be useful in monitoring of leukemia in children.

Prenatally Diagnosed Turner Syndrome and Cystic Hygroma: Incidence and Reasons for Referrals

Objective: The objective of this study was to evaluate the incidence and reasons for referrals for prenatally detected Turner syndrome and cystic hygroma cases among prenatal cases performed between 1998 and 2007. Methods: In this study 3,595 amniocentesis, chorionic villus and cordocenthesis materials obtained between 1998 and 2007 were evaluated. Among prenatal cases, 23 Turner syndrome cases were also evaluated according to their referral reasons. Among the indications of prenatal cases, cystic hygroma was evaluated according to karyotype results. Results: Twenty-three cases were Turner Syndrome in which 7 cases were detected to have mosaic pattern. The indications for prenatal diagnosis for the cases were cystic hygroma in 11 cases, missed abortion in 6 cases, advanced maternal age in 5 cases and positive screening test results in 1 case. Among 18 cases having cystic hygroma detected by ultrasonography, 8 cases (44.4%) were found to have a 45,X karyotype, 3 cases were found to be mosaic Turner syndrome (16.7%), 5 cases (27.7%) had normal karyotype, 1 case (5.6%) 47,XX,+13 and 1 case (5.6%) 47,XX,+21. Conclusion: The present study indicates the importance of cystic hygroma in prenatal diagnosis of Turner Syndrome and other aneuploidies.

Diverse phenotypic and genotypic presentation of RAG1 mutations in two cases with SCID.

Severe combined immunodeficiencies (SCID) comprise a spectrum of genetic defects that involve both humoral and cellular immunities. Defects in recombinating activating gene 1 (RAG1), RAG2, Artemis, or LIG4 can disrupt V(D)J recombination. Defective V(D)J recombination of the T and B cell receptors is responsible for T−B−NK+SCID. Amorphic mutations in RAG1 and RAG2 cause T−B−NK+SCID, whereas hypomorphic mutations cause an immunodeficency characterized by oligoclonal expansion of TCRγδ T cells, severe CMV infection and autoimmunity. First patient is a typical T−B−NK+SCID with clinical and immunologic findings while the second is atypical with normal immunoglobulin levels, CD4 lymphopenia, elevated TCRγδ T cells, persistent CMV infection, and autoimmune hemolytic anemia. These cases are presented to emphasize that mutations in RAG1 gene may lead to a diverse spectrum of clinical and immunologic findings while hypomorphic mutations may be related with autoimmunity and refractory CMV infection during infancy.

MicroRNA expression profiling in children with different asthma phenotypes

An improved understanding of the molecular mechanisms in asthma through exploring the role of microRNAs may offer promise to reveal new approaches for primary prevention and identification of new therapeutic targets in childhood asthma. The primary goal of this study is to identify the microRNAs that play a role in the pathogenesis of asthma in pediatric age group. The secondary goal is to analyze these microRNAs according to the asthma phenotype, atopic status, and severity of the disease exacerbation. To our knowledge, this is the first research project in the literature which studies the relationship between microRNA expression and the severity of childhood asthma. One hundred children between 6 and 18 years old with a diagnosis of asthma, and 100 age‐matched healthy children were enrolled in this study, and the analyses of microRNA expression profiles were performed in the Medical Genetics Laboratories of Ege University between November 2009 and June 2010. The expression of 10 microRNAs were shown to be higher in patients with more severe asthma, and the expression of these microRNAs were also found to be higher in patients who present with more severe acute asthma exacerbation symptoms (P < 0.001). Also, five microRNAs were found to be expressed more than twofold in allergic patients when compared to non‐allergic participants (P <0.001). Asthma is one of the best examples of complex genetic diseases, and further studies, which will investigate the relationship between these microRNAs and their target genes, are needed to learn more about the specific roles of microRNAs in respiratory diseases. Pediatr Pulmonol. 2016;51:582–587.

A novel mutation in two families with pycnodysostosis

Pediatric Genetics, Faculty of Medicine,Ege University, Izmir, TurkeyCorrespondence to Taha R. Ozdemir, MD, Department of Medical Genetics,Faculty of Medicine, Ege University, Bornova 35100, Izmir, Turkey;Tel: +90 232 3904917; fax: +90 232 3903971;e-mail: dr.tahaoz@gmail.comReceived 13 July 2012 Accepted 25 March 2013

Evolution of Genetic Techniques: Past, Present, and Beyond

Genetics is the study of heredity, which means the study of genes and factors related to all aspects of genes. The scientific history of genetics began with the works of Gregor Mendel in the mid-19th century. Prior to Mendel, genetics was primarily theoretical whilst, after Mendel, the science of genetics was broadened to include experimental genetics. Developments in all fields of genetics and genetic technology in the first half of the 20th century provided a basis for the later developments. In the second half of the 20th century, the molecular background of genetics has become more understandable. Rapid technological advancements, followed by the completion of Human Genome Project, have contributed a great deal to the knowledge of genetic factors and their impact on human life and diseases. Currently, more than 1800 disease genes have been identified, more than 2000 genetic tests have become available, and in conjunction with this at least 350 biotechnology-based products have been released onto the market. Novel technologies, particularly next generation sequencing, have dramatically accelerated the pace of biological research, while at the same time increasing expectations. In this paper, a brief summary of genetic history with short explanations of most popular genetic techniques is given.

Effects of Manisa propolis on telomerase activity in leukemia cells obtained from the bone marrow of leukemia patients

Propolis is a resinous material collected by honeybees and obtained from beehives that has anticancer effects by inducing apoptosis. The aim of this study is to investigate the effect of propolis on human telomerase reverse transcriptase (hTERT) in the leukemia cells obtained from leukemia patients. Four different bone marrow cell cultures from each of four leukemia cases were prepared. The 60 ng/ml, 30 ng/ml and 15 ng/ml working concentrations of propolis were administered to three cultures of each patient, while one culture contained only culture medium. hTERT mRNA expression levels of cells were detected at 24 h, 48 h and 72 h using the LightCycler 2.0 instrument. A significant decrease in hTERT expression levels was observed in the 60 ng/ml concentration of propolis. In conclusion,Manisa propolis may also have a potential effect on the expression of hTERT in leukemia—particularly owing to its constituent chrysin.

Association between bronchopulmonary dysplasia and MBL2 and IL1-RN polymorphisms.

The imbalance between pro‐inflammatory and anti‐inflammatory cytokines may play a role in the development of bronchopulmonary dysplasia (BPD) in preterm infants. Mannose binding lectin (MBL) codon 54 and interleukin 1 receptor antagonist gene (IL1‐RN) polymorphisms cause genetic predisposition to increased risk of infection and inflammation, therefore may increase the risk of BPD. The aim of this study was to investigate the relationship between MBL, IL1‐RN gene polymorphisms and BPD development in preterm infants.