No abstract

Mosaicism for trisomy 17 in amniocyte cultures is a rare finding, whilst postnatal cases are exceptional. In order to gain insight into the possible effects of the distribution of the trisomic line and of uniparental disomy (UPD) on embryofoetal development, we have performed follow-up clinical, cytogenetic and molecular investigations into three newly detected prenatal cases of trisomy 17 mosaicism identified in cultured amniotic fluid. In the first case, the pregnancy ended normally with the birth of a healthy girl, and analysis of newborn lymphocytes and of multiple extra-embryonic tissues was indicative of confined placental mosaicism. The second case was also associated with a normal pregnancy outcome and postnatal development, and only euploid cells were found in peripheral blood after birth. However, maternal isodisomy 17 consequent to a meiosis II error and loss of a chromosome 17 homologue was detected in peripheral lymphocytes postnatally. In the third case, pathological examination after termination of pregnancy showed growth retardation and minor dysmorphisms, and the trisomic line was detected in foetal skin fibroblasts. In addition, biparental derivation of chromosome 17 was demonstrated in the euploid lineage. These results, together with previously reported data, indicate that true amniotic trisomy 17 mosaicism is more commonly of extra-embryonic origin and associated with normal foetal development. Phenotypic consequences may arise when the trisomic line is present in foetal tissues. Case 2 also represents the first observation of maternal UPD involving chromosome 17; the absence of phenotypic anomalies in the child suggests that chromosome 17 is not likely to be subject to imprinting in maternal gametes.

We report cytogenetic and molecular investigations performed in two cases of mosaic trisomy 8 combined with mosaic sex chromosome aneuploidy. In a 35-year-old female, presenting with short stature, gonadal dysgenesis, and a multiple congenital anomalies/mental retardation syndrome typical of trisomy 8, chromosome analysis from peripheral lymphocytes showed the presence of three cell lines, whose karyotypes were 45,X (59.2%), 46,X,+8 (1.2%), and 47,XX,+8 (39.6%), respectively. The same cell lines were found in a skin fibroblast culture, though in different proportions. The second patient, a 9-month-old male with multiple skeletal abnormalities, showed a 47,XY,+8 and a 47,XXY cell line in both peripheral lymphocytes (61.7% and 38.3%, respectively) and skin fibroblasts (92.8% and 7.2%, respectively). To determine the events underlying the origin of these complex karyotypes we performed Southern blot and polymerase chain reaction (PCR) analysis using polymorphic DNA markers from the X chromosome and from chromosome 8. Both supernumerary chromosomes 8, and, in case 2, the two X chromosomes, appeared to be identical, lacking detectable recombination events. We conclude that, in both cases, the most likely mechanism underlying the origin of the mosaic cell lines was formation of a normal zygote, followed by mitotic errors during early divisions.

A patient with mental retardation and clinical manifestations suggestive of Noonan syndrome was found to have in her peripheral lymphocytes multiple small accessory marker chromosomes, varying in number from one to five per cell and in size from about half the size of the q arm of a G group chromosome to less than a centromere. Occasionally, in the more elongated markers, a G-positive or a C-positive band could be identified, or the marker had the appearance of a ring. The origin and significance of these marker chromosomes are discussed.

Recent reports indicated the clinical feasibility and biological therapeutic potentiality of epigenetic treatments with VPA + ATRA or ATRA alone and suggested the capability of these agents in rendering neoplastic cells more sensitive to chemotherapy. Therefore, we designed treatments consisting of LoDAC preceded by the sequential administration of VPA+/LoATRA or LoATRA alone, according to the clinical condition of patients, to treat AML patients not eligible for intensive therapy. Aims of this study were to evaluate: the efficacy of these approaches in term of response rate and toxicity; the biological changes occurring in the leukemic clone in relation to the clinical response, by a multiparametric in vivo translational experimental approach.From September 2006 to June 2007, 5 patients (pts) with de novo and 5 with relapsed AMLs were enrolled. The median age was 66 years (range: 46–81 yrs), the mean percentage of BM leukemic infiltration was 60% (range 30–81%);as cytogenetics 5 pts showed complex karyotype. Four patients (1= de novo; 3=relapsed) received an induction treatment with VPA+LoATRA+LoDAC (VPA):VPA at the initial dose of 10 mg/kg/die orally escalated, to reach the therapeutic VPA plasma levels (>50μg/ml),days 1–55, LoATRA 25 mg/m2/die orally, days 7–55 and LoDAC 40 mg/sc at day (d)10 and 45 for 7 d. In responders, therapy was repeated up to a maximum of 3 cycles with a 20 days rest period. Six patients (4 = de novo; 2 = relapsed), received LoATRA alone (days 1–55) because of coexisting co-morbidities , followed by LoDAC as described. Peripheral blood (Pb) and BM samples for biological studies were collected at d 0,7,14,21,35,55. Responses were evaluated after the first cycle of therapy according to the IWC criteria. A complete remission (CR) was observed in 4 cases (2 relapsed = VPA; 2 de novo= LoATRA), while 2 de novo pts (LoATRA) showed a major response (MR).In the 6 responders PB recovery (Hb>9g/dl; PMN>1000/m 3and PLTS>50.000/m3), was observed within a median time of 42 d (range: 35–50 d), while the median time of BM blast clearance was 35 d (range 25–50 d). Of the remaining 4 pts, 1 died during induction, at 45 d for cardiac failure, 3 maintained a stable disease and died 7, 5 and 3 months(mo) later. As to July 2007, 2 pts (Lo ATRA) persisted in CR at 2 and 4 mo, while 2 pts (VPA) relapsed at 3 and 4 mo from CR. Five pts are still alive at 4+, 5+, 5+, 5+, and 9+ mo.Biological assays showed that in mononuclear samples from the 4 CR patients, phenotypic changes including: the increased percentage of cells in S phase; cytochemical changes (myelo-monocytic differentiation); decreased expression of early myeloid/progenitor immunophenotypic markers (HLA-DR, CD34, CD117), which paralleled the increase of late myeloid differentiation markers (CD11b, CD15 or CD14), started to be measurable before LoDAC administration. In conclusion, the sequential therapy with VPA and/or LoATRA + LoDAC are well tolerated out-patient therapies that enabled a CR in a sizeable portion of our cases. In addition, these treatments induce AML blast phenotypical changes that may increase their sensitivity to LoDAC, whose molecular basis is currently under investigation.