Investigating the effects of PTEN mutations on cGAS-STING pathway in glioblastoma tumours.

BACKGROUND: PTEN is a tumour suppressor gene and well-known for being frequently mutated in several cancer types. Loss of immunogenicity can also be attributed to PTEN loss, because of its role in establishing the tumour microenvironment. Therefore, this study aimed to represent the link between PTEN and cGAS-STING activity, a key mediator of inflammation, in tumour samples of glioblastoma patients. METHODS: Tumour samples of 36 glioblastoma patients were collected. After DNA isolation, all coding regions of PTEN were sequenced and analysed. PTEN expression status was also evaluated by qRT-PCR, western blot, and immunohistochemical methods. Interferon-stimulated gene expressions, cGAMP activity, CD8 infiltration, and Granzyme B expression levels were determined especially for the evaluation of cGAS-STING activity and immunogenicity. RESULTS: Mutant PTEN patients had significantly lower PTEN expression, both at mRNA and protein levels. Decreased STING, IRF3, NF-KB1, and RELA mRNA expressions were also found in patients with mutant PTEN. Immunohistochemistry staining of PTEN displayed expressional loss in 38.1% of the patients. Besides, patients with PTEN loss had considerably lower amounts of IFNB and IFIT2 mRNA expressions. Furthermore, CD8 infiltration, cGAMP, and Granzyme B levels were reduced in the PTEN loss group. CONCLUSION: This study reveals the immunosuppressive effects of PTEN loss in glioblastoma tumours via the cGAS-STING pathway. Therefore, determining the PTEN status in tumours is of great importance, like in situations when considering the treatment of glioblastoma patients with immunotherapeutic agents.

20-year experience on prenatal diagnosis in a reference university medical genetics center in Turkey

Background/aim: Although cutting edge procedures such as cell-free fetal DNA isolation from maternal blood are now available, invasive prenatal tests are still being used extensively for prenatal diagnosis. The study aims to evaluate the demographic data, indications, and cytogenetic results of 9297 results of patients who underwent prenatal invasive testing for genetic analysis that were referred for the last 20 years in a University Medical Genetics Center. Materials and methods: The records of 8363 amniocenteses, 626 chorionic villus, and 308 cordocenteses samples were retrospectively evaluated and analyzed regarding referral reasons, indications and their cytogenetic results. The total numbers and the percentages of each group were recorded; Chi-square and logistic regression analyses were performed to give the statistical likelihood of different events. Results: The number of referrals decreased significantly after 2009. Risk of having trisomy 21 as well as trisomy 13 and 18 significantly increased in parallel with advanced maternal age. When the 21­25 age group was compared to the older age groups in terms of having a trisomy 21 pregnancy, the risk doubled in the 36­40, 5 times higher in 41­45 and 10-fold in 46­50 age groups. No significant linear correlation between maternal serum screening test results and trisomy 21 was found, however the difference between the pregnancies whom cut-off value above and below 1/250 in maternal serum screening test were significant. Conclusion: These data have provided useful information on the frequency of referrals to the reference genetics department, and the feasibility of genetic services. By reviewing the indications and their corresponding results, we can offer invaluable insights that will be useful in genetic counseling and also in the development of more effective genetic strategies.

Clinical and molecular aspects of PTEN mutations in 10 pediatric patients.

INTRODUCTION: PTEN gene mutations are responsible for the PTEN hamartoma tumor syndrome (PHTS). In this study, clinical and molecular findings of patients carrying PTEN mutations are presented. Our aim is to contribute to genotype-phenotype correlation and define the most common findings of the syndrome in pediatric patients. METHODS AND MATERIALS: Ten molecularly confirmed PHTS patients from seven families were included in the study. All patients were examined by a clinical geneticist. Laboratory test results were obtained from hospital records. Sequencing of PTEN gene was performed. Variant interpretation was done in accordance with 2015 recommendations from the American College of Medical Genetics. RESULTS: Macrocephaly was the most common clinical finding, involving all patients. This was followed by skin lesions, neurodevelopmental delay, and pathologic cranial magnetic resonance imaging findings. Seven different heterozygous PTEN gene variants were found in seven families. Four of these were located in exon 5, which has been described as a hot spot area for the PTEN gene. Four mutations were novel. A wide range of phenotypic and genotypic spectra was found in our study group. CONCLUSION: Screening of PTEN mutations in patients with macrocephaly is recommended due to an increased risk of cancer. Further cases are needed to make a phenotype-genotype correlation in PHTS.

A Neurofibromatosis Noonan Syndrome Patient Presenting with Abnormal External Genitalia

Neurofibromatosis Noonan syndrome (NFNS) is a rare RASopathy syndrome, resulting from NF1 gene mutations. NFNS is characterized by phenotypic features of both neurofibromatosis type 1 (NF1) and Noonan syndrome. Plexiform neurofibromas (PNFs) are an unusual finding in NFNS. A seven year-old girl with typical clinical features of NF1 was referred to our clinic due to short stature and abnormal genital appearance. Due to dysmorphic features, a clinical diagnosis of NFNS was considered in the patient and, following molecular analysis, revealed a novel heterozygous c.3052_3056delTTAGT (p.L1018X) variant in the NF1 gene. Although evaluation for genital virilization, including karyotype and hormonal studies were normal, imaging studies revealed a diffuse genital PNF. Although PNFs are seen rarely in NFNS, this should be considered in the differential diagnosis of genital virilization in these patients to prevent unnecessary testing.

The genetics of recurrent hydatidiform moles: new insights and lessons from a comprehensive analysis of 113 patients.

Hydatidiform mole is an aberrant human pregnancy characterized by early embryonic arrest and excessive trophoblastic proliferation. Recurrent hydatidiform moles are defined by the occurrence of at least two hydatidiform moles in the same patient. Fifty to eighty percent of patients with recurrent hydatidiform moles have biallelic pathogenic variants in NLRP7 or KHDC3L. However, in the remaining patients, the genotypic types of the moles are unknown. We characterized 80 new hydatidiform mole tissues, 57 of which were from patients with no mutations in the known genes, and we reviewed the genotypes of a total of 123 molar tissues. We also reviewed mutation analysis in 113 patients with recurrent hydatidiform moles. While all hydatidiform moles from patients with biallelic NLRP7 or KHDC3L mutations are diploid biparental, we demonstrate that those from patients without mutations are highly heterogeneous and only a small minority of them are diploid biparental (8%). The other mechanisms that were found to recur in patients without mutations are diploid androgenetic monospermic (24%) and triploid dispermic (32%); the remaining hydatidiform moles were misdiagnosed as moles due to errors in the analyses and/or their unusual mechanisms. We compared three parameters of genetic susceptibility in patients with and without mutations and show that patients without mutations are mostly from non-familial cases, have fewer reproductive losses, and more live births. Our data demonstrate that patients with recurrent hydatidiform moles and no mutations in the known genes are, in general, different from those with mutations; they have a milder genetic susceptibility and/or a multifactorial etiology underlying their recurrent hydatidiform moles. Categorizing these patients according to the genotypic types of their recurrent hydatidiform moles may facilitate the identification of novel genes for this entity.

Von Hippel-Lindau Disease: The Importance of Retinal Hemangioblastomas in Diagnosis.

Von Hippel-Lindau (VHL) disease is a familial cancer syndrome characterized by benign or malignant tumors which may involve more than one system. Retinal hemangioblastomas are usually the initial manifestation of VHL disease and can cause vision loss. A 32-year-old man presented to our clinic with vision loss in the left eye for 2 months. He had a history of cerebral hemangioblastoma operation. Family history showed that his mother had unilateral vision loss and died because of renal cell carcinoma. Ophthalmologic examination revealed multiple retinal hemangioblastomas in both eyes. VHL gene sequencing was performed and heterozygous p.R161X mutation was detected. His sister and daughter were also found to have the same variant. A treatment and follow-up plan was initiated for the patient and affected family members. Considering VHL disease in the differential diagnosis of retinal hemangioblastomas has a very important role in the early detection of life-threatening tumors in these patients.

Rapid Molecular Genetic Diagnosis with Next-Generation Sequencing in 46,XY Disorders of Sex Development Cases: Efficiency and Cost Assessment.

BACKGROUND/AIM: The aim of this study was to use targeted next-generation sequencing (TNGS) including all known genes associated with 46,XY disorders of sex development (DSD) for a fast molecular genetic diagnosis. METHODS: Twenty pediatric patients were recruited, and 56 genes related to 46,XY DSD were sequenced using TNGS. The time elapsed between initial appointment and final diagnosis as well as the mean expenditure was determined. RESULTS: A total of 9 (45%) mutations in 4 different genes were identified. Mutations in the HSD17B3 gene were observed in 6 (30%) patients. A heterozygous mutation in WT1 gene and a hemizygous mutation in SRY gene were detected in patients with gonadal dysgenesis. One patient had a homozygous mutation in LHCGR gene. Prior to the molecular diagnosis, the mean number of clinical visits, time elapsed until diagnosis, and expenditure were 27.4 ± 14.6 visits, 5.9 ± 4.1 years per patient, and USD 2,142 ± 1,038, respectively. With TNGS, time elapsed until diagnosis was significantly reduced (3 days), and expenditure per patient was only one third of the conventional approach (USD 761). CONCLUSIONS: TNGS is an efficient, rapid, and cost-effective technique for mutation detection in 46,XY DSD.

Molecular spectrum of α-globin gene mutations in the Aegean region of Turkey: first observation of three α-globin gene mutations in the Turkish population.

Molecular test results of 231 individuals referred to our molecular genetics laboratory for analysis of α-globin gene mutations between the years 2007 and 2013 were evaluated. Analysis of α-thalassemia gene mutations was performed using reverse dot-blot hybridisation, which includes 21 common mutations. Twelve distinct α-thalassemia mutations and 23 different genotypes have been detected in the Aegean region of Turkey. The most frequent mutations were -α3.7 (52.28 %), -(α)20.5 (14.74 %), --MED (10.53 %), and αPA-1α (8.77 %). Three α-thalassemia mutations (αcd142α, --SEA, and αICα), which are more prevalent in Southeast Asia, are identified for the first time in Turkey in this study. We find that a broad spectrum of α-thalassemia mutations is present in the Aegean region of Turkey. The results obtained in this study may help inform decisions in the design and implementation of prevention strategies and diagnostic approaches.