Burak Durmaz

The missing “link”: an autosomal recessive short stature syndrome caused by a hypofunctional XYLT1 mutation

Proteoglycan (PG) synthesis begins with the sequential addition of a “linker chain”, made up of four sugar residues, to a specific region of a core protein. Defects in the enzymes catalyzing steps two to four of the linker chain synthesis have been shown to cause autosomal recessive human phenotypes while no mutation has yet been reported in humans for the xylosyltransferases 1 and 2 (XT1 and XT2), the initiating enzymes in the linker chain formation. Here, we present a consanguineous Turkish family with two affected individuals presenting with short stature, distinct facial features, alterations of fat distribution, and moderate intellectual disability. X-rays showed only mild skeletal changes in the form of a short femoral neck, stocky and plump long bones and thickened ribs. Using a combination of whole-exome sequencing (WES), determination of homozygous stretches by WES variants, and classical linkage analysis, we identified the homozygous missense mutation c.C1441T in XYLT1, encoding XT1, within a large homozygous stretch on chromosome 16p13.12-p12.1. The mutation co-segregated with the phenotype in the family, is not found in over 13,000 alleles in the exome variant server and is predicted to change a highly conserved arginine at position 481 (p.R481W) located in the putative catalytical domain. Immunostaining of primary patient fibroblasts showed a loss of predominance of Golgi localization in mutant cells. Moreover, western blot analysis of decorin in cell culture supernatant demonstrated glycosylation differences between patient and control cells. Our data provide evidence that functional alterations of XT1 cause an autosomal recessive short stature syndrome associated with intellectual disability.

Pontocerebellar hypoplasia type III (CLAM): Extended phenotype and novel molecular findings

Pontocerebellar hypoplasia (PCH) is a heterogeneous group of disorders characterized by abnormally small cerebellum and brainstem. Recently a rare, novel form of PCH has been reported called cerebellar atrophy with progressive microcephaly (CLAM). Here we report a second family of CLAM with additional phenotypic features and novel molecular findings. Three-year old index patient had severe developmental delay and presented with short stature and microcephaly. Her cranial magnetic resonance imaging revealed hypoplasia of the cerebellum, brainstem and cerebrum associated with hypoplasia of the corpus callosum. Brainstem auditory evoked potentials revealed hearing loss and visual evoked potentials confirmed the optic atrophy. She also had seizures with two posterior epileptic foci on electroencephalogram. Molecular analysis revealed a homozygous haplotype between the markers D7S802 and D7S630 within the originally linked region, narrowing the critical region from 20 Mb to 7 Mb. Two highly relevant candidate genes, CROT and SLC25A40 located in this region were sequenced, but no causative mutations identified. Our case provides additional clinical characteristics on the previously described features of this new entity, and reducing the critical region will now allow systematic positional cloning efforts to identify the causative gene.

Prospective Evaluation of Whole Genome MicroRNA Expression Profiling in Childhood Acute Lymphoblastic Leukemia

Dysregulation of microRNA (miRNA) expression contributes to the pathogenesis of several clinical conditions. The aim of this study is to evaluate the associations between miRNAs and childhood acute lymphoblastic leukemia (ALL) to discover their role in the course of the disease. Forty-three children with ALL and 14 age-matched healthy controls were included in the study. MicroRNA microarray expression profiling was used for peripheral blood and bone marrow samples. Aberrant miRNA expressions associated with the diagnosis and outcome were prospectively evaluated. Confirmation analysis was performed by real time RT-PCR. miR-128, miR-146a, miR-155, miR-181a, and miR-195 were significantly dysregulated in ALL patients at day 0. Following a six-month treatment period, the change in miRNA levels was determined by real time RT-PCR and expression of miR-146a, miR-155, miR-181a, and miR-195 significantly decreased. To conclude, these miRNAs not only may be used as biomarkers in diagnosis of ALL and monitoring the disease but also provide new insights into the potential roles of them in leukemogenesis.

A Severe α Thalassemia Case Compound Heterozygous for Hb Adana in α1 Gene and 20.5 kb Double Gene Deletion

We report a 6-year-old boy diagnosed as transfusion dependent chronic nonspherocytic hemolytic anemia since 40 days old. Hemoglobin H inclusions were detected with brilliant cresyl blue preparation. His parents were found to be normal on physical examination. His mother had hemoglobin level of 9.34 g/dL, accompanied by typical thalassemic changes of the red cells, and inclusion bodies were also detected with brilliant cresyl blue staining. His father had normal hemoglobin level and borderline red cell indices. Mutation analysis using strip assay capable of detecting 22 mutations within the alpha genes was performed for the proband and the parents which revealed that the case was compound heterozygous for Hb Adana in alpha1 gene and 20.5 kb double gene deletion. The father was found to be heterozygous for Hb Adana alpha1 gene whereas the mother was found to be compound heterozygous for 20.5 kb double gene deletion and 3.7 kb single gene deletion. It is well known that non deletional forms of HbH disease are more severe than the deletional forms. This case represents another example of the nondeletional mutation underlying Hb Adana, which is rarely seen in alpha1 gene, and illustrates the distinctive phenotypes of both the deletional and nondeletional forms of hemoglobin H disease within the same family.

The Association of minor congenital anomalies and childhood cancer.

Although the association of some congenital malformations and specific genetic syndromes is well understood, the association between minor anomalies and cancer is not well known. In recent years some researchers have reported studies establishing this association in different types of cancer. In this study, we aimed to investigate the prevalence and patterns of age‐independent minor anomalies in childhood cancer patients.

Long-term evaluation of chromosomal breakages after radioisotope synovectomy for treatment of target joints in patients with haemophilia

Summary.  Radioisotope synovectomy (RS) is defined as the intra‐articular injection of radioisotopic agents with the aim of fibrosis on hypertrophic synovium in the target joint. The aim of this study was to investigate genotoxic effects on lymphocytes and malign transformation induced by Yttrium90 (Y90) and Rhenium186 (Re186) in children with haemophilia undergone RS. Forty haemophilia patients were enrolled. The mean age was 16.4 ± 6.2 years (range: 8–40). Y90 was used for knees, Re186 was used for other joints. For safety, cytogenetic analysis was performed to determine potential chromosomal changes after RS procedure at three different time points as prior to procedure, 3rd day and 90th day. For the stimulation of chromosomal breakages, diepoxybutane was used (DEB test). Chromosomal breakages (CBs) were found in 23 patients (67.6%) prior to RS. We have found CBs additionally in nine of 11 patients who had no CBs prior to RS after 3 days of radioisotope exposure. At that time, the patients who had CBs were 29 (85.2%). At day 90, only 21 patients revealed (61.7%) CBs. The mean frequency of CBs slightly but not significantly increased in the 3rd day. However, there was a significant decreasing trend between 3rd and 90th days. Radioisotope synovectomy with Y90 and Re186 does not seem to induce the genotoxic effects significantly on peripheral blood lymphocytes. However, CBs even after one year in the re‐evaluation of four patients, significant decrease in the number of CBs between the 3rd and 90th days and de novo CBs after exposure may be accepted as warning signals for young population. It should also be pointed out that families and patients be informed properly related with historical and potential dangers of radioisotopic agents.

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.

Congenital supratentorial cystic hemangioblastoma Case report and review of the literature

Supratentorial hemangioblastomas are rarely encountered tumors even in the pediatric population; an extensive review of the literature has revealed approximately 118 cases. However, only five of these occurred in infants, and three occurred during the first 2 months of life. A 5-week-old boy presented with emesis, irritability, a bulging anterior fontanelle, and a head circumference that had gradually expanded since birth. His medical and family histories were uninformative in terms of cancer or inherited diseases. Magnetic resonance imaging demonstrated a large loculated cyst with a heterogeneous contrast-enhancing 3-cm nodule, first pushing the left frontal and parietal lobes and then displacing into this region. After being exposed via a left frontoparietal craniotomy, the cyst was evacuated by a soft drain, and then the mass was totally excised. The histopathological diagnosis was a reticular variant of hemangioblastoma. Given that von Hippel-Lindau (VHL) gene mutations may be associated with hemangioblastomas, sequencing analysis of the VHL gene was performed; sequencing of the three exons of the VHL gene showed no exonic mutations. Clinical and neuroimaging follow-up of the patient have revealed an improved health status during the last 23 months. The authors reviewed the literature concerning congenital supratentorial hemangioblastomas, and they discuss the clinical and histopathological characteristics and differential diagnosis associated with such lesions.

Gonadotropin-Dependent Precocious Puberty in a Patient with X-Linked Adrenal Hypoplasia Congenita Caused by a Novel DAX-1 Mutation

Background/Aims: X-linked adrenal hypoplasia congenita (AHC) is typically characterized by a DAX-1 gene mutation and hypogonadotropic hypogonadism. However, rare cases with precocious puberty or normal puberty have been reported. Currently, the mechanism of action of the DAX-1 gene on puberty is not clearly known. Case Report: We report a male who was diagnosed as having AHC in the newborn period and detected as having stop codon Q155 X mutation in the DAX-1 gene. This subject developed central precocious puberty when he was 9 months old. Results: This paper is the first case report of AHC, central precocious puberty and a mutation in the DAX-1 gene. DAX-1 gene mutations can result in various phenotypes. Conclusion: In cases with AHC, central precocious puberty can develop rather than hypogonadotropic hypogonadism, which is the most frequently observed puberty disorder related to DAX-1 gene mutations.

Interferon-γ gene and interferon-γ receptor-1 gene polymorphisms in children with tuberculosis from Turkey

Abstract Macrophage activation by interferon-γ (IFN-γ) is important in host resistance to tuberculosis (TB). In this study, the relationships of the +874 T/A polymorphism in the first intron of the IFN-γ gene and intronic (CA)n polymorphic microsatellite marker of the interferon-γ receptor 1 (IFN-γR1) gene to TB susceptibility were investigated in children. Forty children with TB and 67 age-matched controls were included. There were no significant differences between the allele frequencies and genotype frequencies of patient and control groups for the polymorphism +874 T/A in the IFN-γ gene. Differences that were not statistically significant were found between the group of children with TB and the control group for the allelic markers (170 and 180) in the IFN-γR1 gene. The incidence of the allele 170 was higher in patients (30.9%) than in controls (17.4%), whereas the allele 180 was found to be more common in controls (9% vs 1.2%). In conclusion, no significant association was observed between the +874 T/A polymorphism found in the first exon of the IFN-γ gene and TB susceptibility in Turkish children.