STRUCTURAL VARIATIONS OF CHROMOSOME 9

Partial trisomy of chromosome 9 has relatively frequently been observed in liveborn subjects. In the majority of the reported cases breaks occur in the centric segment of the long arm (q11-q13). Two characteristics of this chromosome part, i.e. 9qh+ and inv(9), have been studied. The results of a study of selected samples do not support an association between 9qh+ chromosome anomaly and reproductive failure. The frequency of inv(9) in different samples agrees with those reported by other investigators (1.11—2.32%). An excess of male carriers was found. Aneusomy of recombination has been observed in one case. Partial trisomy of chromosome seems to be the most frequently observed type of unbalanced structural aberration of autosomes in liveborn subjects. Up to now 50 cases have been reported. Three of these have been described as 9q trisomy, the others were 9p trisomies

Particularity of genetic counseling in case of a family carriers of structural aberration of chromosome 6

We discuss the case of a family carriers of structural chromosomal aberration del(6)(q24) in two generations. For the first time revealed in 2 year old girl, the aberration has become a reason for family medical and genetic examination, including prenatal cytogenetic diagnosis. The results of clinical and genetic testing of the proband were compared with published data.

Prognostic Impact Of a Newly Defined Structurally Complex Karyotype In Patients With AML and MDS After Allogeneic Stem Cell Transplantation

Background Allogeneic stem cell transplantation (SCT) is a potentially curative treatment for patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, relapsed disease is a major cause of treatment failure and death after SCT which is dependent on several pretransplantation variables, including cytogenetics. A diagnostic karyotype is a key determinant of outcome and has emerged as one of the most significant prognostic factors and provides the framework for current risk-stratified approaches. Monosomal karyotype (MK) defined by at least two autosomal monosomies, or one autosomal monosomy associated with at least one structural abnormality, is a rather new cytogenetic entity first described in AML by Breems et al., identifying a subset of patients with a dismal prognosis. A structurally complex karyotype has recently been defined as more than or equal to 3 chromosomal aberrations, including at least one structural aberration (Gohring G et al. Blood. 2010;116 (19):3766-3769). A structural aberration is defined as an altered chromosomal structure which can appear as a deletion, duplication, translocation, insertion, inversion, ring chromosome or isochromosome. Here, the presence of a structurally complex karyotype was a better predictor of a very unfavorable prognosis in children with MDS than a monosomal karyotype. Aims The objective of the present study was to determine whether a structurally complex karyotype has a similar adverse prognostic effect in the setting of allogeneic transplantation for adult patients receiving an SCT at Hannover Medical School for AML and MDS. Methods All patients with the diagnosis of AML and MDS who received an SCT from 2006-2011 at our center were retrospectively evaluated. Excluded were patients with ≥ 2 SCT, extramedullary AML as sole manifestation and haplo-identical SCT. Results 248 evaluable patients could be identified, 106 with a normal karyotype, 8 with a core-binding factor (CBF) AML and 134 with an aberrant karyotype. In these 134 patients, a structurally complex karyotype did not allow a better prognostic distinction compared to a monosomal karyotype. As expected, most patients with an aberrant karyotype were transplanted without a prior remission, and only 48 patients (36%) were transplanted in 1st or 2nd complete remission (CR). For all patients who were transplanted in CR the differentiation between a structurally complex karyotype was a better prognostic marker than a monosomal karyotype in terms of relapse and overall survival. When evaluating the subgroup of patients with an aberrant karyotype, patients with a structurally complex karyotype had a significant higher relapse rate compared to patients without a structurally complex karyotype (53% vs. 14%, p<0.01). Also, overall survival was far better without a structurally complex karyotype (29 months vs. 11 months, p<0.01). There was no significant difference in relapse incidence for patients with and without a monosomal karyotype, also OS did not reach statistical significance, though it was better in the cohort without a monosomal karyotype. However, subgroups are small and a further discrimination between a monosomal but not structurally complex karyotype and vice versa could not be performed. Conclusion Patients with a monosomal or structurally complex karyotype had a poor prognosis. Notably, a structurally complex karyotype was associated with a shorter overall survival, even for patients transplanted in complete remission. The presence of a structurally complex karyotype had a stronger prognostic impact on survival after allogeneic transplantation than a monosomal karyotype. Our data strongly suggest further studies to determine the prognostic impact of this newly defined karyotype. Disclosures: No relevant conflicts of interest to declare.

Karyotype and RAPD Analysis in Five Potato Varieties (Solanum tuberosum L.)

Two native and three high yielding potato varieties available in Bangladesh were studied cytogenetically at molecular level to get a preliminary idea about their genomes. These varieties possess 2n = 4x = 48 chromosomes. Each variety has definite centromeric formula. Presence of maximum metacentric chromosomes suggested their karyotypes as symmetric type. The range of individual chromosomal and total length of 2n chromosome complements was also distinct in five varieties. Heteromorphicity regarding centromeric position suggesting the occurrence of structural aberration in respective homologous pairs. Seven primer combinations were used for RAPD finger printing. A few common RAPD bands suggested the sharing of genomic fragments among five varieties. However, each variety showed specific characteristic RAPD bands. Therefore, each variety has characteristic karyotype and RAPD markers. DOI: http://dx.doi.org/10.3329/bjb.v41i1.11088 Bangladesh J. Bot. 41(1): 105-110, 2012 (June)

Association of MTHFR Polymorphisms and Chromosomal Abnormalities in Leukemia

Genetic variation in MTHFR gene might explain the interindividual differences in the reduction of DNA repaired and the increase of chromosome breakage and damage. Nowadays, chromosomal rearrangement is recognized as a major cause of lymphoid malignancies. In addition, the association of MTHFR polymorphisms with aneuploidy was found in several studies, making the MTHFR gene as a good candidate for leukemia etiology. Therefore, in this study, we investigated the common sequence variation, 677C>T and 1298A>C in the MTHFR gene of 350 fixed cell specimens archived after chromosome analysis. The distribution of the MTHFR polymorphisms frequency was compared in leukemic patients with structural chromosome abnormality and chromosome aneuploidy, as well as in those with no evidence of chromosome abnormalities. We observed a significant decrease in the distribution of T allele in 677C>T polymorphisms among patients with chromosomal abnormalities including both structural aberration and aneuploidy. The same significance result also found in patients with structural aberration when compare with the normal karyotype patients. Suggesting that polymorphism in the MTHFR gene was involved in chromosome abnormalities of leukemia. However, further investigation on the correlation with the specific types of chromosomal aberrations is needed.