Matild Dobos

Y-chromosome markers in Turner syndrome: Screening of 130 patients.

Background: The presence of Y-chromosome material in patients with Turner syndrome (TS) is a risk factor for the development of gonadoblastoma. Cytogenetic analysis detects Y-chromosome mosaicism in about 5% of Turner patients. However, if Y-chromosome sequences are present in only a few cells, they may be missed by routine analysis. The use of molecular techniques to detect the presence of Y-chromosome fragments in such patients is becoming increasingly important. Aim: The objective of our study was to analyze cryptic Y-chromosome derivatives in Hungarian TS patient population by real-time PCR (RT-PCR). Subjects and metohds: Cytogenetic and RT-PCR methods were used to examine peripheral blood DNA of 130 Hungarian patients with TS for the presence of Y-chromosome. With RT-PCR, 4 regions throughout the Y-chromosome were analyzed. Results: Initial cytogenetic karyotyping assessing 10–50 metaphases revealed 3 patients with Y-chromosome positivity. RT-PCR revealed further 6 patients with Y-chromosome, who were initially considered as Y-negatives by standard kayotyping. The consecutive cytogenetic analysis of a large number (about 100) of metaphases (in 5 patients) and/or FISH (in 6 patients) however, also confirmed the presence of the Y-chromosome in these patients. Prophylactic gonadectomy was carried out in all 9 patients and 1 of them was diagnosed as having bilateral gonadoblastoma without clinical symptoms. Conclusions: We recommend a routine molecular screening for hidden Y-chromosome sequences in Turner patients, who are negative for Y-chromosome by conventional cytogenetic analysis, in order to calculate the future risk of developing gonadoblastoma.

Donor-cell myelodysplastic syndrome developing 13 years after marrow grafting for aplastic anemia

Donor-cell-derived hematopoietic malignancy is a rare event after bone marrow transplantation. Most cases in the literature occurred within the first year. We present a rare case of a female patient who had a bone marrow transplant for severe aplastic anemia (SAA) at the age of two and a half years from her human leukocyte antigen-identical brother. She developed a myelodysplastic syndrome (refractory cytopenia with multilineage dysplasia) 12 years later. Initially, the malignant clone was of recipient origin, but within several months, progression to a clinically more aggressive refractory anemia with excess blasts (RAEB) was accompanied by the outgrowth of a new clone of donor origin. In this report we provide evidence proving that the patients final malignant clone arose in donor cells: cytogenetic analysis of the marrow showed a male karyotype and a t(3;21)(q26;q21) in all 62 metaphases analyzed. Interphase fluorescence in situ hybridization showed that all identifiable cells contained the Y chromosome. We conclude that donor-cell-derived hematopoietic malignancy after bone marrow transplantation can occur even after many years. We believe that the 13 years that elapsed between the transplant and the development of RAEB in our case represent the longest latency period in the literature.

Chromosome Mutations and Chromosome Stability in Children Treated with Different Regimes of Immunosuppressive Drugs

The chromosome mutations and the number of sister chromatid exchanges induced by different kinds of immunosuppressive treatment were investigated in children and adults with certain types of renal diseases. The aim of the study was to find among the treatment schedules those promising good therapeutic results with the least mutagenic effects. A slightly decreased chromosome stability was found in the patients treated by cyclophosphamide therapy.

Ring Chromosome 18: Clinical, Cytogenetic and Molecular Genetic Studies on Four Patients

Abstract Ring chromosomes are a rare chromosomal aberration but have meanwhile been reported for nearly all human chromosomes. We describe four de novo carriers (1 boy and 3 girls) of ring chromosome 18 (r(18)): while three patients had a non-mosaic 46,r(18) karyotype, the fourth was a mosaic: mos 46,XX, r(18)/46,XX, der(18). Phenotypically, the boy showed only minor anomalies, but the female probands presented several clinical features, among them microcephaly, a moderate to severe muscular hypotonia, psychomotoric retardation and short stature. Major malformations were heart defects, cleft lip and palate and atresia of the external auditory canal. In one girl with very short stature, we found a hypothalamic growth hormone deficiency. By investigating the children over 2,5 years it could be demonstrated that the ring chromosomes were passed regularly through mitosis. The parental origin of the ring was determined in three cases indicating a postzygotic mitotic error.

Darier's Disease Associated with Cutis Verticis Gyrata, Hyperprolactinaemia and Depressive Disorder

Cutis verticis gyrata (CVG) is a descriptive term for a thickened scalp condition in which deep furrows, cere-briform or gyriform convoluted ridges are seen (1). It has been classified into primary and secondary types (2). The secondary form has been linked to local inflammatory skin conditions and to systemic illnesses, such as amy-loidosis, myxoedema, acanthosis nigricans, acromegaly and pachydermoperiostosis. Chromosomal abnormalities such as Turner syndrome, Klinefelter syndrome, and fragile sites on chromosomes X, 12, and 9 have also been associated with CVG (3–6). Darier’s disease (DD) is an autosomal dominantly inheredited skin disorder, characterized by loss of adhesion between epidermal cells and abnormal keratinization. The disorder is caused by mutations of the

CHROMOSOME INSTABILITY DURING IMMUNSUPPRESSIVE TREATMENT

The mutagenic effect of cytostatic therapy of children suffering from non-tumorous diseases was studied. The chromosomes of cultured peripheral blood of children suffering from autoimmune diseases and membranoproliferative glomerulouephritis were analysed. 26 children treated with cyclophosphamide /3-5 mg/kg/day/ were examined. On the 4th-6th week of the treatment the number of chromosomal breaks increased to 18,6%, in contrast to the previously found 1,5%. The frequency of aberrations remained on a higher level during the therapy, afterwards it decreased, and reached again the control level 6 month later. At a smaller dose /1-2 mg/kg/day/ the frequency of chromosomal breaks was 5,5% /2 children examined only/. Chlorambucyl and 6-mercaptopurine also induced chromosomal aberrations in 12% and 13,5% respectively. The in vitro chromosome stability was examined in 5 patients during cytostatic therapy. The number of mutations induced in vitro by Lycurim was about the double that of healthy untreated children. Presumably the higher number of chromosomal mutations and the decreased chromosome stability induced both by the immunsuppressive treatment contribute to the higher frequency of malignancies in this group of patients.

Mutability in Down's syndrome

Certain conditions, such as Downs syndrome/DS/and Fanconi anaemia are associated with a higher frequency of malignancies. The number of children with DS suffering from leukaemia was investigated in Hungary. 0,76% of the leukaemic children were affected by DS, while only 0,07% in the general population. The present work aimed at demonstrating whether an increased in vitro mutability can be induced by chemicals in DS. Various concentrations of two alkylating drugs/Zitostop and Licurim/were used as mutagen. 1500 mitosis in the lymphocyte cultures of 5 children with DS were analysed after the in vitro addition of Zitostop, and a further 930 cells from other 5 DS patients were examined under the effect of Licurim. Using a given dose of either drug, a higher rate of induced chromosome mutations could be detected, as compared to controls. An increased rate of mutability can therefore be responsible for the higher incidence of malignancies in at least some of the syndromes predisposing to leukaemia and malignant tumours.