Genetic Analysis of RASD1 as a Candidate Gene for Schizophrenia

Background: RASD1 encodes Dexamethasone-induced Ras-related protein 1 (Dexras1), a protein with a critical role in signal transduction in neurons. There is a strong suspicion that dysfunction of Dexras1 might contribute to the pathogenesis of neuropsychiatric diseases. Related to its functions in intracellular signaling pathways, Dexras1 has a potential role in the etiology of schizophrenia because of its close interaction with NOS1, NOS1AP, and NMDAR, which have previously been associated with schizophrenia. Aims: To investigate the association of RASD1 variants with schizophrenia in a selected cohort from Turkey. Study Design: A case-control study. Methods: We performed targeted sequencing for the two exons, single intron, and untranslated regions of RASD1 gene in 200 individuals with schizophrenia and 100 healthy controls of Turkish origin. Results: Two rare variants, RASD1 (NM_016084.5): c.722A>T and c*31G>A were identified in individuals with schizophrenia but not in any controls. The c.722A>T was found in a single individual with schizophrenia and is a missense heterozygous variant in the second exon of RASD1, which is extremely rare in GnomAD. The other variant, c*31G>A, which was found in another individual from this schizophrenia cohort, has not been reported previously. Seven previously identified common single nucleotide polymorphisms were also detected; however, they were not significantly associated with schizophrenia in this study cohort. Conclusion: Our findings suggest that rare variants of RASD1 might be contributing to the etiopathogenesis of schizophrenia. Further studies are needed to elucidate the underlying mechanism of this association.

Clinical and radiologic evaluation of a Turkish family with hypochondroplasia and a rare FGFR3 variant.

OBJECTIVES: Hypochondroplasia (HCH) is characterized by disproportionate short stature and regarded as a milder form of achondroplasia (ACH), which is another skeletal dysplasia, both caused by variants in fibroblast growth factor receptor 3 (FGFR3) gene. HCH diagnosis is based on the clinical features and skeletal survey findings. The most common FGFR3 variant in HCH affects the codon 540, leading to substitution of asparagine with lysine in about 70% of patients. CASE PRESENTATION: Herein, we described the clinical and radiographical manifestations of HCH in affected members of a Turkish family with very rare Asn540Thr (c.1619A>C) variant within hot spot of the gene for this condition. CONCLUSIONS: This is a very rarely reported variant in the literature and this report is the first case with this variant in Turkish population. The report also presents the phenotypic variability within a family with the same variant, which is inherent to HCH.

Phenotypic and molecular characterization of five patients with PIK3CA-related overgrowth spectrum (PROS).

Somatic and germline PI3K-AKT-mTOR pathway pathogenic variants are involved in several segmental overgrowth phenotypes such as the PIK3CA-related overgrowth spectrum (PROS), Proteus syndrome, and PTEN hamartoma tumor syndrome. In this study, we describe five patients with PROS. We identified by high-throughput sequencing four different somatic PIK3CA pathogenic variants in five individuals. The Glu726Lys variant, which was previously reported in megalencephaly-capillary malformation-polymicrogyria (MCAP) syndrome, was identified in two patients with unclassified PROS. The Cys420Arg substitution, which was previously reported in CLOVES, was found in a patient with fibroadipose hyperplasia. Additionally, relatively rare pathogenic variants, His1047Tyr and Tyr1021Cys, were detected in two patients with MCAP. Therefore, we suggest performing deep sequencing of PIK3CA in all patients with suspected PROS, instead of targeted polymerase chain reaction for hotspot pathogenic variants.

Mosaic Small Supernumerary Marker Chromosome Derived from Five Discontinuous Regions of Chromosome 8 in a Patient with Neutropenia and Oral Aphthous Ulcer.

Small supernumerary marker chromosomes (sSMCs) are characterized as additional centric chromosome fragments which are too small to be classified by cytogenetic banding alone and smaller than or equal to the size of chromosome 20 of the same metaphase spread. Here, we report a patient who presented with slight neutropenia and oral aphthous ulcers. A mosaic de novo sSMC, which originated from 5 discontinuous regions of chromosome 8, was detected in the patient. Formation of the sSMC(8) can probably be explained by a multi-step process beginning with maternal meiotic nondisjunction, followed by post-zygotic anaphase lag, and resulting in chromothripsis. Chromothripsis is a chromosomal rearrangement which occurs by breakage of one or more chromosomes leading to a fusion of surviving chromosome pieces. This case is a good example for emphasizing the importance of conventional karyotyping from PHA-induced peripheral blood lymphocytes and examining tissues other than bone marrow in patients with inconsistent genotype and phenotype.

Skin-Dominant Phenotype in a Patient with H Syndrome: Identification of a Novel Mutation in the SLC29A3 Gene.

H syndrome (OMIM 602782) is a very rare autosomal recessive genodermatosis with multisystem involvement. Hallmarks of this disorder are juvenile onset and progressive, hyperpigmented, hypertrichotic lesions with histiocytic infiltration. Associated systemic manifestations form a long list, and there is high variability between patients. In some patients, dysmorphic and other systemic features may be so subtle that the disorder may readily be mistaken as an acquired skin disease and treated as such. Herein, we report a novel homozygous c.1339G>A (p.Glu447Lys) mutation in the SLC29A3 gene in a patient with skin-dominant presentation of H syndrome. Additionally, due to the present case, double superior vena cava can be added to the list of possible cardiovascular manifestations of H syndrome.

Association Between N363S and BclI Polymorphisms of the Glucocorticoid Receptor Gene (NR3C1) and Glucocorticoid Side Effects During Childhood Acute Lymphoblastic Leukemia Treatment.

OBJECTIVE: Glucocorticoids (GCs) are the key drugs for the treatment of pediatric acute lymphoblastic leukemia (ALL). Herein, investigation of the relationship between the N363S and BclI polymorphisms of the GC receptor gene (NR3C1) and the side effects of GCs during pediatric ALL therapy was aimed. MATERIALS AND METHODS: N363S and BclI polymorphisms were analyzed in 49 patients with ALL treated between 2000 and 2012. The control group consisted of 46 patients with benign disorders. The side effects of GCs noted during the induction and reinduction periods were evaluated retrospectively according to the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0. RESULTS: The BclI allele and genotype frequencies were found similar in the two groups. No N363S polymorphism was detected in either of the groups. During induction, dyspepsia was found more frequently in the CG than in the CC (wild-type) genotype (36.4% vs. 5.3%, p=0.018) and depression symptoms more frequent in patients with the G allele (CG+GG) than the CC genotype (39.3% vs. 10.5%, p=0.031). During reinduction, Cushingoid changes, dyspepsia, and depression symptoms were more frequent in patients with the G allele (CG+GG) than in patients with the CC genotype (48.1% vs. 17.6%, p=0.041; 29.6% vs. 0.0%, p=0.016; 40.7% vs. 11.8%, p=0.040, respectively). CONCLUSION: In our study, patients with the BclI polymorphism were found to have developed more frequent side effects. We think that the BclI polymorphism should be considered while designing individualized therapies in childhood ALL.

Investigation of androgen receptor gene mutations in a series of 21 patients with 46,XY disorders of sex development.

AIM: Androgen receptor (AR) gene mutations are the leading cause of 46,XY disorders of sex development (DSD) and are associated with varying degrees of androgen insensitivity. The aim of this study is to investigate AR gene mutations in 46,XY DSD patients with normal testosterone secretion, either normal or high testosterone/dihydrotestosterone (T/DHT) ratio and normal SRD5A2 gene analysis, collectively, suggestive of androgen insensitivity syndrome (AIS). METHODS: We direct sequenced all eight exons of the AR gene in 21 index patients with varying degrees of undervirilization. RESULTS: We detected AR gene alterations in five patients. In patients with complete AIS we found p.Val30Met in exon 1 and p.Gly689* in exon 4. One patient with partial AIS had p.Gln712Glu in exon 4. In two patients with partial phenotype, we found common p.Glu213Glu (c.639G>A) SNP, and an additional p.Ile817Ile (c.2451T>C) mutation was found in one of these two patients. DISCUSSION: Despite the fact that T/DHT ratio is frequently used in diagnosis of AIS, lack of precisely determined cutoffs compromises correct diagnosis. Hence, depending on clinical and biochemical findings solely may delay correct diagnosis. Direct sequence analysis of the AR is essential for precise diagnosis of AIS.

Molecular spectrum of PIK3CA gene mutations in patients with nonsmall-cell lung cancer in Turkey.

AIMS: The aim of the present study was to obtain the first data for the phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA) mutation frequency among nonsmall-cell lung cancer (NSCLC) patients in Turkey. All exons of the PIK3CA gene were investigated by sequence analysis in 40 NSCLC tumor tissue samples. RESULTS: The 1634A>C mutation, which has previously been identified in many cancers including NSCLC, was identified in three tumor tissue samples in the present study. Interestingly, a second mutation (1658_1659delGTinsC) was also identified in these patients. The concurrence of these two mutations has been reported as the Cowden syndrome, which is known to be a cancer predisposition syndrome. This finding is important since it may be an indicator of the underlying cancer predisposition syndrome in NSCLC patients. Moreover, four novel mutations were identified in the present study. However, in vitro studies are required to evaluate the effects of these mutations on kinase activation. CONCLUSIONS: The high frequency of PIK3CA mutations exerts important clinical implications for targeted therapy. This finding indicates that therapeutic agents targeting the phosphatidylinositol 3-kinase (PI3K) would be beneficial in the NSCLC subpopulation.

Axenfeld-Rieger syndrome associated with truncus arteriosus: a case report.

The aim of this presentation was to report a case with Axenfeld-Rieger syndrome (ARS) associated with truncus arteriosus (TA). We present a 14-year-old boy with ARS in whom the diagnosis was confirmed by ophthalmologic examination and developmental defects of the teeth and facial bones. Echocardiography revealed TA. With this case demonstrating the association between ARS and TA, the range of reported cardiac malformations is enlarged and the importance of cardiologic evaluation is emphasized in patients with ARS.

The role of genetic counseling on decisions of pregnant women aged 35 years or over regarding amniocentesis in Turkey.

We investigated the effects of genetic counseling given before amniocentesis that is given based on maternal serum screening (using the cut-off value of 1/250) and genetic sonogram results (+/- abnormal ultrasound marker) on pregnant women who are 35 years and older age. Their attitudes towards amniocentesis after genetic counseling were evaluated. Among 340 women, 223 (65.6%) were in the high-risk group and 117 (34.4%) were in the low-risk group according to non-invasive test results. After counseling, 216 pregnant women (167 cases have high-risk, 49 cases who had low-risk) decided to have amniocentesis while 124 women (56 with high-risk and 68 with low-risk) declined it. Fourteen abnormal karyotypes were detected. All pregnant women who had fetuses with chromosomal aberrations were in high-risk group. Our study shows that screening by non-invasive prenatal diagnostic tool has an effect on families' choice of amniocentesis. The use of these test results during counseling decreased the number of amniocentesis in a ratio of 36.5%.

The genotoxic effects of hepatitis B virus to host DNA.

Chronic viral hepatitis is the main cause of chronic liver disease, cirrhosis and hepatocellular carcinoma throughout the world. Hepatitis B virus (HBV) has mutagenic effects on somatic cells. HBV may be showing these mutagenic effects through its viral proteins or through integrating into host DNA. The aim of this study was to determine whether HBV has a genotoxic effect on host DNA or not. Peripheral blood lymphocytes of 31 chronic HBV patients and 20 chronic HBV carriers were cultured in order to make cytogenetic evaluation by observing chromosome breakage and cytological evaluation by the micronucleus (MN) test. Their results were compared with 20 healthy controls. For each individual, 100 metaphase chromosome spreads were analysed. Around 190-1091 binucleated cells were observed and MN were scored for each individual. Our results showed significantly higher frequencies of chromosome breaks in chronic HBV patients and in HBV carriers than in the control group. There was no difference in MN scores among HBV patients, HBV carriers and healthy carriers. Based on our data, we conclude that chronic HBV patients and carriers have chromosomal instability and that HBV carriers are as affected as patients because of their same chromosome breakage levels.