Duygu DURSUN, SAFİYE AKTAŞ, AYŞE PINAR ERÇETİN, ZEKİYE SULTAN ALTUN, Kamer MUTAFOĞLU, Nur OLGUN

Nörofibromatozis Tip 1 olgularında DNA tamir genlerinin ekspresyonunun klinik önemi,

Amaç: Nörofibromatozis Tip 1 (NF1), çeşitli fenotiplere sahip, sık görülen otozomal dominant genetik bir hastalıktır. NF1 hastalarının klinik çeşitliliğinin genetik nedeni sorgulanmaktadır. DNA onarım genleri DNA’daki hataların onarımından sorumludur. Bu çalışmada DNA onarım genlerinin ekspresyonunu ve onların NF1 hastalarındaki klinik önemini nörofibrom, hamartomatöz lezyon, diğer tümörler ya da ailesel NF1 varlığı ile karşılaştırarak analiz etmek ve gen ekspresyonları ile klinik bulgular arasında ilişki olup olmadığını belirlemek amaçlandı. Yöntemler: NF1’li hastalar ve NF1 ile birlikte malignitesi olan hastalar çalışmaya alındı. Kontrol grubu olarak da benzer yaş grubundaki her hangi bir hastalığı olmayan çocuklar ve NF1 ile ilgisi olmayan maligniteli olgular oluşturdu. Çalışma toplam 46 olgu içermekteydi: 36 NF1 hastası (30 çocuk; 6 ebeveyn), hiç bir hastalığı olmayan 8 kontrol olgusu, rabdomiyosarkomlu NF1 olmayan 2 kontrol olgusu çalışmaya alındı. Her bir hasta ve kontrol grubundan periferik kandan mononükleer hücre izolasyonu yapıldı. RNA izolasyonu ve cDNA dönüşümünden sonra, her bir olguda Real-Time PCR ile DNA onarımı ile ilişkili 84 genin ekspresyonu (standart array, SABiosciences) belirlendi. Ekspresyonların kontrol grubuna göre kat değişiklikleri ve T test ile p değeri karşılaştırmalı gruplarda değerlendirildi. Bulgular: Araştırma grubunu 36 NF1 hastası, kontrol grubunu ise 8 sağlam çocuk ve 2 adet de NF1 ile ilişkisi olmayan maligniteli olgu (rabdomiyosarkom) oluşturmaktadır. 8 kontrol olgusunun yaş ortalaması 17 ± 7,03 (10-30 yaş) (ortanca 13 yaş) idi. NF1 olgularının 17’si kadın 19’u erkekti. NF1’li olgularımız için tanı anındaki yaş ortalaması 10,08 ± 8,86 (9 ay- 38 yaş) (ortanca 8 yaş) iken hastalarımızın çalışmaya alınan ebeveynlerinin yaş ortalaması 40,50 ± 1,22 (39-42 yaş) (ortanca 40 yaş) idi. 36 hastanın, 17’si nörofibromlu, 17’si hamartomatöz lezyonluydu. 1 hastada rabdomiyosarkom (RMS) gözlenmiş, 1 hasta meme kanseri ve 4 hasta da optik gliomluydu. NF1 olgularında, PNKP, RAD18, XAB2, XRCC3, XRCC4 ve XRCC5 genlerinin ekspresyonu kontrol grup ile karşılaştırıldığında azaldı (p

Clinical significance of dna repair genes expressions in neurofibromatosis Type 1 cases

Objective: Neurofibromatosis Type 1 (NF1) is a a common autosomal dominant genetic disorder that has a variable phenotype. The genetical causes of clinical variability of NF1 patients is questioned. DNA repair genes are responsible for proofreading the missing in the DNA. We aimed to analyze expression of DNA repair genes and their clinical significance in NF1 patients; comparing exsistance of neurofibroma or hamartomatous lesions or other tumours or existance of NF1 in the family. The other aim of this study was to determine whether any relationship between gene expressions and clinical findings. Methods: NF1 patients and malignancy with NF1 pateints were included in this study. In the control gruop children that they are in the similar age group and they have no disease and no malignacy group were included. This study included total 46 cases. 36 NF1 patients (30 children; 6 parents), 8 control cases without any disease, two control cases with rhabdomyosarcoma without NF1 were included in this study. The mean age of control group was 17 ± 7.03 (10-30 age) (median 13 age). In the NF1 pateints gruop 17 of them are female, and 19 are male. The mean age at diagnosis is 10.08 ± 8.86 (9 months- 38 age)(median age 8) for children and 40.50 ± 1.22 (39-42 age) (median age 40) for parents. Among 36 patients, 17 had neurofibromas, 17 had hamartomatous lesions. Rhabdomyosarcoma (RMS) was observed in one patient, breast cancer in one patient and four patients suffered optic glioma. Peripheral blood was obtained from each cases and mononuclear cells were separated. After RNA isolation and cDNA converting, expressions of 84 genes related with DNA Repair in standard array (SABiosciences) were determined by Real-Time PCR for each case. Fold changes and p values compared with control groups and fold changes evaluated with T test and p value in the comperative groups. Results: 36 NF1 patients, 8 healthy children as a control and 2 cases no NF1 relationship with malignancy (rhabdomyosarcoma) were included in the study group. In NF1 cases PNKP, RAD18, XAB2, XRCC3, XRCC4 and XRCC5 genes were down- regulated compared with control group. In NF1 cases having neurofibromas, POLB was over expressed; while ERCC3, LIG1, MGMT, MRE11A, MPG, MSH6, PARP2, PRKDC, RAD51B, RAD52, RPA3, SMUG1, TREX1, UNG were downregulated compared with the NF1 cases without neurofibromas (p<0.05, T test). RAD18 is the downregulated and statistical significant gene for existence of NF1 in the family. There are gene expression fold change differences determined when malign tumor cases with/without NF1 were compared. DDB2, MGMT, MLH1, POLB UNG, XPA are increased. Conclusion: Our results may point toward a role of gene expression changes of DNA repair system to be predictive for clinical manifestations in NF1 cases.

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