Ajlan Tükün

Biology of stem cells in human umbilical cord stroma: in situ and in vitro surveys.

Cells in the umbilical cord stroma have gained attention in recent years; however, differentiation to certain lineages in humans has been demonstrated in few studies. Unlike bone marrow MSCs, human umbilical cord stroma cells (HUCSCs) are far from being well characterized. This study attempts to describe proliferation, structural, and differentiation properties of these cells to account for their exceptional nature in many aspects. Cellular dynamics, cellular structure, and the degree of transformations during expansion and differentiation into mesenchymal and neuronal lineages were examined in vitro over a 10‐month period. Comparisons with human bone marrow MSCs regarding differentiation were performed. HUCSCs in culture revealed two distinct cell populations, type 1 and type 2 cells, that possessed differential vimentin and cytokeratin filaments. Corresponding cells were encountered in cord sections displaying region‐specific localization. α‐Smooth muscle actin and desmin filaments, which were evident in cord sections, diminished through passages. No difference was noted regarding type 1 and type 2 cells in differentiation to chondrogenic, adipogenic, and osteogenic lineages, whereas a preferential differentiation was noted in neuronal lineage. Relative success was achieved by production of chondrocytic spheres and osteogenic monolayers, whereas adipocytes were immature compared with bone marrow MSCs. The presence of neuronal markers suggests that they transform into a certain state of maturity under neurogenic induction. Conclusively, HUCSCs retain their original phenotype in culture without spontaneous differentiation, have a limited lifespan, and bear multipotent stem cell characteristics. Given these characteristics, they may be generally considered progenitor cells if manipulated under appropriate conditions and deserve further study to be potentially used in cell‐based therapies.

Molecular alterations in the TP53 gene of peripheral blood cells of patients with chronic myeloid leukemia

The TP53 gene has been extensively studied in patients with chronic myeloid leukemia (CML), both in chronic phase and in blast crisis. Mutations in the gene were found in up to 30% of the patients, especially among those in blast crisis. We report the results of an analysis of 29 blood samples from CML patients: 8 samples from chronic phase patients, 8 from patients in the accelerated phase, and 13 from patients in blast crisis. By using genomic DNA, we sequenced PCR products of the coding exons and most introns of the TP53 gene, finding genetic changes in 30% of the blast crisis samples and 12% in chronic phase. All mutations were found in introns and were previously unreported. Immunocytochemical studies revealed accumulation of TP53 in blood cells of samples both from chronic phase and blast crisis patients. Since these samples had no TP53 mutations, we believe that wild type TP53 accumulates in blood cells of CML patients. Our results, therefore, indicate that molecular changes in coding regions of the TP53 gene are rare. The significance of the abundance of intronic changes should be investigated further. Accumulation of wild type TP53 in CML cells may indicate an additional mechanism involving this gene in the pathogenesis of this disease. Genes Chromosomes Cancer 21:2–7, 1998.

Identification of frequency and distribution of the nine most frequent mutations among patients with 21-hydroxylase deficiency in Turkey.

UNLABELLED Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders mainly due to defects in the steroid 21-hydroxylase (CYP21A2) gene. METHODS To determine the mutational spectrum in the Turkish population, the CYP21A2 active gene was analyzed in 100 unrelated patients with the classical form of 21-hydroxylase deficiency using PCR and RFLP. RESULTS Mutations were detected in 78 patients: 64 patients were homozygous for one mutation, seven patients were compound heterozygous with different mutations on each chromosome, two patients were homozygous for two different mutations, five patients were heterozygous, and 22 patients harbored none of the tested mutations. The most frequent mutation was IVS2-13A/C (28.5%), followed by large gene deletion (17%), Q318X (11.5%), I172N (4%), V281L (3.5%), R356W (3.5%), 8-bp (3%), complex alleles (2%), P30L (1%) and E6 cluster (1%). CONCLUSION The distribution of mutation frequencies in our study was slightly different from those previously reported in Turkey and in other parts of the world.

Gonadal dysgenesis and the Mayer-Rokitansky-Kuster-Hauser syndrome in a girl with 46,X,del(X)(pter-->q22:).

Abstract The association of mullerien duct with gonadal dysgenesis is extremely rare. We report such a case in a 19 year-old white woman with a 46,X,del(X)(pter→q22:) karyotype.

The Frequency of A1298C and C677T Polymorphisms of the Methylentetrahydrofolate Gene in Turkish Patients with Rheumatoid Arthritis: Relationship with Methotrexate Toxicity.

The C677T and A1298C polymorphisms of methylenetatrahydrofolate reductase (MTHFR) gene are reported to have a relationship to methotrexate (MTX) metabolism, with conflicting results. The aim of this study was to determine the frequency of MTHFR C677 T and A1298C gene polymorphisms in a group of Turkish RA patients and evaluate its association with MTX toxicity. Sixty-four patients with RA and 31 control subjects with a mean age of 48.7 ±12.5 and 46.2 ± 13.4 years, were enrolled to the study. Demographic characteristics were obtained and MTX-related adverse effects were recorded in the patient group. The A1298C and C677T polymorphisms of the MTHFR gene were analyzed and the distribution of genotypes according side effects, were determined. The frequency of MTHFR C677T and A1298C polymorphisms were similar in the patient and control groups. Folic acid supplementation with a mean dose of 5mg folic acid/week, was present in all patients. Thirty-six of the 64 patients showed adverse effects to MTX treatment, and MTX had been discontinued in 12 (18.8%) patients due to side effects and/or inefficacy. MTHFR C677T and A1298C gene polymorphisms were found to be similar in patients with and without MTX-related adverse events. In conclusion, A1298C and C677T polymorphisms in the MTHFR gene, were not related with MTX-related toxicity in RA patients receiving folate supplementation. Further studies are needed to illuminate the polymorphisms in other enzymes that might be responsible from the MTX toxicity in patients suffering from RA.

Common fragile sites associated with the breakpoints of chromosomal aberrations in hematologic neoplasms.

Fragile sites are specific regions of chromosomes prone to breakage when cells are cultured under specific conditions. These sites are divided into two classes: common and rare. Common fragile sites are expressed in all individuals at different frequencies, whereas rare ones are found only in certain individuals. Common and rare fragile sites have been shown to display a number of characteristics of instability being preferential sites for chromosomal deletions, duplications, and rearrangements. Moreover, a majority of mapped oncogenes are located at or near these fragile sites. These observations have led to the suggestion that both classes of fragile sites may play a significant role in chromosomal rearrangements involved in oncogene activation or tumor supressor gene inactivation. For these reasons, involvement of common and rare fragile sites and their relevance to specific chromosome breakpoints in cancer have received much attention. In this study, which reports on the cytogenetic findings obtained from 256 patients with chronic myelocytic leukemia, 103 with acute myelocytic leukemia, 40 with acute lymphocytic leukemia, 33 with myelodysplastic syndrome, we documented the fragile sites involved in chromosomal aberrations involving oncogenes, tumor supressor genes, and other known genes important in cell cycle regulation localized at these sites.

The clinical and genetic heterogeneity of mixed gonadal dysgenesis: does “disorders of sexual development (DSD)” classification based on new Chicago consensus cover all sex chromosome DSD?

Clinical findings illustrate the wide spectrum of the phenotypic manifestations of 45,X/46,XY mosaicism in the sex chromosome disorders of sex differentiation (DSD). The objective of study is to evaluate the characteristics of 45,X/46,XY patients and questioning of their place within the DSD categorization. The clinical findings of 11 patients with 45,X/46,XY mosaicism are described including the presentation, gonadal morphology, genital anatomy, and the hormone levels among 285 patients with DSD evaluated. Sixty-seven patients were diagnosed with sex chromosome DSD (50 Turner, three Klinefelter, ten 45,X/46,XY gonadal disgenesis, one 45X/46,XY ovotesticular DSD, one 47,XYY ovotesticular DSD, and two 46,XX/46,XY ovotesticular DSD). The type and the percentage of patients with 45,X/46,XY mosaicism were as follows: Four cases of mix gonadal dysgenesis, four cases of partial gonadal dysgenesis, two cases of complete gonadal dysgenesis, one case of ovotesticular DSD. On the other hand, another patient that has 45,X/46,XX mosaicism was diagnosed with MGD with the presence of the streak gonad on the right side and the testis on the other side. Conclusion: We suggest that sex chromosome DSD categorization can include 45,X/46,XY PGD and 45,X/46,XY CGD. Mixed gonadal dysgenesis may be also placed among the disorders of testicular differentiation of 46,XY DSD subdivision.

Hemophagocytosis associated with leukemia: a striking association with juvenile myelomonocytic leukemia

The aim of this study was to describe the characteristics and outcome in a group of pediatric patients with hematological malignancies who developed hemophagocytosis at diagnosis or during the disease course. Eight patients with hematological malignancy and associated hemophagocytosis were included. The initial diagnosis was juvenile myelomonocytic leukemia (JMML) in five, nonlymphoblastic leukemia (ANLL) in two, and T-cell lymphoma associated with myeloproliferative syndrome in one patient. Hemophagocytosis was concomitantly present at the time of diagnosis of the primary disease in four of the five patients with JMML and in the two patients with ANLL. Three had abnormalities related to chromosome 8 [(trisomy 8, monosomy 8, and t (8;13) (p11; p12)], and one had inversion 16. Multiple chromosomal losses were present in one patient, including both chromosomes 8 and 16. Bone marrow karyotyping revealed 46, XX; 47, XXX mosaicism in one patient. Two patients had PTPN11 mutation and one patient k-RAS mutation. The patients with JMML and neurofibromatosis (n = 2), the patient with lymphoma and t (8;13) positive AML, and a fourth patient with PTPN11 mutation did not remit and had unfavorable outcomes.

Disorders of sexual development: an overview of 18 years experience in the pediatric Endocrinology Department of Ankara University.

ABSTRACT Introduction: Disorders of sexual development (DSD) occur when the appearance of the internal and/or external genitalia is at variance with normal development for either sex. We reviewed the characteristics of patients with DSD. Patients: Two hundred and eight children aged from newborn to 19 years with DSD from 1990 to 2008. Results: 46,XY DSD (52.4%) was more common than 46,XX DSD (34.6%) and gonadal differentiation disorders (12.99%). Thirty-six (33.02%) patients were diagnosed with androgen resistance syndrome, 41 (37.61%) had 5α-reductase deficiency, 23 (21.10%) had testosterone synthesis disorders. Congenital adrenal hyperplasia was the most frequent underlying cause of 46,XX DSD. Conclusion: There are many difficult aspects in the diagnosis and management of DSD. Gender assessment teams of endocrine centers need a multidisciplinary approach for the diagnosis, medical and surgical treatment, genetic counseling, and psychosocial support of these patients.

Clinical Review of 95 Patients with 46,XX Disorders of Sex Development Based on the New Chicago Classification

STUDY OBJECTIVE The aim of our study was to determine the etiologic distribution of 46,XX disorder of sexual development (DSD) according to the new DSD classification system and to evaluate the clinical features of this DSD subgroup in our patient cohort. PARTICIPANTS The evaluation criteria and clinical findings of 95 46,XX patients were described by clinical presentation, gonadal morphology, genital anatomy, associated dysmorphic features, presence during prenatal period with/without postnatal virilization, hormonal characteristics, and presence or absence of steroidogenic defects among 319 patients with DSD. RESULTS Types and ratios of each presentation of our 95 patients with 46,XX DSD were as follows: 82 had androgen excess (86.3%): (74 had classical congenital adrenal hyperplasia, 2 had CAH variant possibility of P450-oxidoreductase gene defect), 6 had disorders of ovarian development (6.3%): (1 patient had gonadal dysgenesis with virilization at birth with bilateral streak gonad, 4 patients had complete gonadal dysgenesis, and 1 patient had ovotesticular DSD) and 7 had other 46,XX DSD. Two sisters, who had 46,XX complete gonadal dysgenesis,were diagnosed with Perrault Syndrome with ovarian failure due to streak gonads and associated with sensorineural deafness. CONCLUSION 46,XX DSD are usually derived from intrauterine virilization and CAH is the most common cause of 46,XX DSD due to fetal androgen exposure.