DETAE Genetics

ÖZET Amaç: Atriyal izomerizm, kalp gibi normalde asimetrik olan organlardaki lateralizasyon defektleriyle karakterize olan doğumsal bir anomalidir. Atriyal izomerizmin, erken gelişim sırasındaki moleküler defektler nedeniyle oluştuğu düşünülmektedir. NKX2-5, kardiyogenezi başlatan ve kardiyogenezin sonraki transkripsiyonel olaylarını düzenleyen kalbe özgü bir transkripsiyon faktörüdür. HAND1 ise kalpte ekspres olan, asimetrik ekspresyon paterni ile karakterize başka bir transkripsiyon faktörüdür. Çalışmamızda, NKX2-5 ve HAND1 genlerindeki mutasyonların atriyal izomerizm etiyolojisinde rol oynayıp oynamadığını anlamak için, atriyal izomerizm hastalarında bu iki geni incelemeyi amaçladık. Yöntemler: Bu vaka-kontrol çalışması atriyal izomerizm tanısı alan veya atriyal izomerizm nedeniyle cerrahi tedavi gören 70 hasta ve HAND1 için 80, NKX2-5 için, 40 sağlıklı kontrolden oluşturulmuştur. NKX2-5 ve HAND1 genlerinin tüm ekzonları ve ekzon-intron sınırları SSCP ile analiz edilmiş, şüpheli örnekler mutasyon analizi için dizilenmiştir. Bilinen polimorfizmler ve mutasyonlar için uygun restriksiyon enzimi ile enzim kesimi uygulanmıştır. Hasta ve kontrol grupları arasındaki allel ve genotip sıklıklarını Ki-kare ve Fisher testleri kullanılarak karşılaştırıldı. Bulgular: Kontrol ve hastalarda, HAND1 geninin intronik bölgesinde bir C>G dönüşümü tanımladık. Mutant allelin hasta grubundaki sıklığı (%11.42) kontrol grubundakinden (%2.5) daha yüksek bulundu (p=0.046). Mutant allel taşıyan genotipler ile atriyal izomerizm arasındaki bağlantı sınırda anlamlı bulundu (p=0.054). NKX2-5 geninde, bir hastada heterozigot durumda Q170X (Gln170ter) mutasyonu tanımladık. Tanımlanan dizi farklılıkları ile hastaların klinik özellikleri arasında herhangi bir ilişki bulunmadı. Sonuç: Sonuçlarımız, HAND1 veya NKX2-5 genlerindeki mutasyon veya dizi farklılıklarının, atriyal izomerizm etiyolojisi veya patogenezinde rol oynayabileceğini akla getirmektedir. (Anadolu Kardiyol Derg 2011; 11: 319-28) Anahtar kelimeler: İzomerizm, NKX2-5, HAND1, mutasyon ABSTRACT Objective: Atrial isomerism is a congenital disorder, which is characterized by lateralization defects in normally asymmetrical developing organs like the heart. Atrial isomerism is supposed to be caused by molecular defects during early development. The NKX2-5 is a cardiac specific transcription factor, which initiates and regulates downstream transcriptional cascades of cardiogenesis. The HAND1 is another transcription factor expressed in the heart, and it is characterized by an asymmetrical pattern of expression. In this study, we aimed to test whether mutations in NKX2-5 and HAND1 genes play a role in the etiology of atrial isomerism. Methods: This case-control study consisted of 70 patients who underwent surgical treatment for congenital heart defects including atrial isomerism, 80 healthy subjects (HAND1 gene) and 40 healthy subjects (NKX2-5 gene). All exons and exon-intron boundaries of NKX2-5 and HAND1 genes were analyzed by SSCP, and suspected samples were sequenced for mutation analysis. Digestion with appropriate restriction enzymes was performed for analysis of known mutations and polymorphisms. The frequencies of the alleles and the genotypes were compared among patient and control groups using the Chi-square and the Fisher tests when appropriate. Results: In intronic region of HAND1 gene, we identified a C>G substitution both in patients and controls. Frequency of mutant allele (11, 42%) was found higher (p=0.046) in patient group than that of the control group (2.5%). Association between atrial isomerism and genotypes with mutant allele was found borderline significant (p=0.054). In NKX2-5 gene, we identified heterozygous Q170X (Gln170ter) mutation in one patient. We did not found any correlation between defined sequence variations and clinical properties of the patients. Conclusion: Our results suggest that mutations or sequence variations in HAND1 or NKX2-5 genes may play role in etiology or pathogenesis of atrial isomerism. (Anadolu Kardiyol Derg 2011; 11: 319-28)

There is preliminary evidence that the local renin-angiotensin system (RAS) could affect neoplastic hematopoiesis. The aim of this study is to search messenger RNA (mRNA) expressions of the essential RAS elements in myeloid and lymphoid hematological neoplastic disorders. Forty-six patients with newly diagnosed myeloid (AML, biphenotypic leukemia, CML) or lymphoid (CLL, NHL, B-ALL, T-ALL) hematological disorders were included in the study. In the lymphoid group, the median expression values of RENIN, ACE1, ACE2 and ANGIOTENSINOGEN (ANGTS) mRNAs were 1.96%, 0.42%, 0.00% and 0.00%, respectively; in the myeloid group, 0.73%, 1.55%, 0.04% and 0.006%, respectively. In the lymphoid group, RENIN levels were significantly higher (p = 0.001), whereas ACE1 and ACE2 levels were significantly higher in the myeloid group (p values were 0.013 and 0.010, respectively). ANGTS levels were similar in both groups. In patients with non-ALL lymphoid malignancies, RENIN expressions were significantly higher when compared to ALL patients (p = 0.004). All patients with active disease had significantly higher RENIN mRNA expression levels than patients without active disease (2.03% vs 0.30%) (p = 0.034). The result of our present study indicates that the activities of local RAS may differ in distinct disease states such as leukemia and lymphomas.

The current treatment of chronic phase chronic myeloid leukemia (CML) consists of oral tyrosine kinase inhibitors (TKIs). However, high-risk CML may present with an aggressive course which may result in blastic crisis or a "difficult-to-manage" state with available treatments. The aim of this paper is to report a patient with complicated CML resistant to treatment and progressed despite the administration of bosutinib, imatinib mesylate, nilotinib, dasatinib, interferon alpha 2a, cytotoxic chemotherapy, and allogeneic hematopoietic stem cell transplantation. The striking point of this case story is that no Abl kinase domain mutation against TKIs has been detected during this very complicated disease course of CML. Meanwhile, challenging cases will always be present despite the hope and progress in CML in the TKI era.

Mesial temporal sclerosis (MTS) is the most frequent cause of drug resistant symptomatic partial epilepsy. The mechanism and genetic background of this unique pathology are not well understood. Aquaporins (AQP) are regulators of water homeostasis in the brain and are expressed in the human hippocampus. We explored the role of AQP genes in the pathogenetic mechanisms of MTS through an evaluation of gene expression in surgically removed human brain tissue. We analyzed AQP1 and 4 mRNA levels by quantitative real-time polymerase chain reaction and normalized to ABL and cyclophilin genes, followed by immunohistochemistry for AQP4. Relative expressions were calculated according to the delta Ct method and the results were compared using the Mann-Whitney U test. Brain specimens of 23 patients with epilepsy who had undergone surgery for MTS and seven control autopsy specimens were investigated. Clinical findings were concordant with previous studies and 61% of the patients were seizure-free in the postoperative period. AQP1 and 4 gene expression levels did not differ between MTS patients and control groups. Immunofluorescence analysis of AQP4 supported the expression results, showing no difference. Previous studies have reported contradictory results about the expression levels of AQP in MTS. To our knowledge, only one study has suggested upregulation whereas the other indicated downregulation of perivascular AQP4. Our study did not support these findings and may rule out the involvement of AQP in human MTS.

B-lineage acute lymphoblastic leukemia (B-ALL) is a common subtype of acute leukemia in children. PAX5 plays a central role in B-cell development and differentiation. In this study, we analyzed PAX5 expression levels, transactivation domain mutations/ ...

Background/aim: The canonical Wingless-type (WNT) pathway is involved in normal hematopoietic cell development and deregulated WNT signaling is implicated in the development of hematological malignancies. Dickkopf 1 (DKK1) acts as a modulator of the β-catenin regulated canonical pathway. Activation of DKK1 leads to apoptosis and growth suppression, whereas silencing by promoter hypermethylation results in abnormal WNT activation. The secreted inhibitor Dickkopf can antagonize WNT signaling by competitively binding to low density lipoprotein receptors (LRPs) 5 and 6. Materials and methods: We studied DKK1 gene promoter methylation and investigated DKK1, β-catenin, LRP5, and LRP6 mRNA levels in B-cell acute lymphoblastic leukemia (B-ALL) patients (n = 90). Methylation-specific PCR and bisulfite sequencing were used for methylation profiling and quantitative real-time PCR was used for mRNA detection. Results: The DKK1 gene was examined for its promoter methylation and only 33% of patients were found methylated. On the other hand, BALL cases showed high expression of DKK1 (P = 0.01), LRP5 (P = 0.04), and LRP6 (P = 0.02) compared to normal bone marrow cells. Conclusion: DKK1 methylation exists in some of cases but is not sufficient for WNT pathway activation alone in pediatric BALL .

Wingless Type (WNT) signaling pathway is an evolutionarily conserved pathway that is crucial for the cell fate determination, survival and expansion of lymphocyte progenitors. It has been demonstrated that deregulated WNT signaling is one of the participating mechanism underlying lymphoid leukemogenesis. Inactivating mutations and methylation in Adenomatous Polyposis Coli (APC) gene, a negative regulator of WNT pathway, can cause ligand independent WNT pathway simulation. In this study, promoter methylation and expression of the APC gene is evaluated in childhood lymphoid and myeloid acute leukemia patients (n= 118) and representative cell lines by using methylation specific PCR (MS-PCR) and real time quantitative PCR (QRT-PCR). APC gene promoter found hypermethylated in the 56% of childhood acute leukemia patients [49.2% of B-cell acute lymphoblastic leukemia (B-ALL), 62.5% of T-cell acute lymphoblastic leukemia (T-ALL) and 64.1% of Acute myeloid leukemia (AML)]. To evaluate the reflection of promoter methylation, APC mRNA levels were examined and found that all acute lymphoblastic leukemia subgroups have statistically lower APC expression levels compared to controls. Although there was no association with clinical parameters, promoter hypermethylation of APC gene seems to be a common epigenetic event in acute leukemia and leading to differential expression levels among different acute leukemia phenotypes.

Human nude SCID is a rare autosomal recessive inborn error of immunity (IEI) characterized by congenital athymia, alopecia, and nail dystrophy. Few cases have been reported to date. However, the recent introduction of newborn screening for IEIs and high-throughput sequencing has led to the identification of novel and atypical cases. Moreover, immunological alterations have been recently described in patients carrying heterozygous mutations. The aim of this paper is to describe the extended phenotype associated with FOXN1 homozygous, compound heterozygous, or heterozygous mutations. We collected clinical and laboratory information of a cohort of 11 homozygous, 2 compound heterozygous, and 5 heterozygous patients with recurrent severe infections. All, except one heterozygous patient, had signs of CID or SCID. Nail dystrophy and alopecia, that represent the hallmarks of the syndrome, were not always present, while almost 50% of the patients developed Omenn syndrome. One patient with hy...

Mesial temporal sclerosis (MTS) is the most frequent cause of drug resistant symptomatic partial epilepsy. The mechanism and genetic background of this unique pathology are not well understood. Aquaporins (AQP) are regulators of water homeostasis in the brain and are expressed in the human hippocampus. We explored the role of AQP genes in the pathogenetic mechanisms of MTS through an evaluation of gene expression in surgically removed human brain tissue. We analyzed AQP1 and 4 mRNA levels by quantitative real-time polymerase chain reaction and normalized to ABL and cyclophilin genes, followed by immunohistochemistry for AQP4. Relative expressions were calculated according to the delta Ct method and the results were compared using the Mann-Whitney U test. Brain specimens of 23 patients with epilepsy who had undergone surgery for MTS and seven control autopsy specimens were investigated. Clinical findings were concordant with previous studies and 61% of the patients were seizure-free in the postoperative period. AQP1 and 4 gene expression levels did not differ between MTS patients and control groups. Immunofluorescence analysis of AQP4 supported the expression results, showing no difference. Previous studies have reported contradictory results about the expression levels of AQP in MTS. To our knowledge, only one study has suggested upregulation whereas the other indicated downregulation of perivascular AQP4. Our study did not support these findings and may rule out the involvement of AQP in human MTS.