1/23. Variable pathogenicity of exon 43del (FAA) in four Fanconi anaemia patients within a consanguineous family.Four Fanconi anaemia group A (FAA) patients within two related consanguineous families are presented: the propositus (male, 13 years, transplanted at age 10), and his three cousins (one male, 8 years, and two female newborns). Assignment of the patients to FAA was based on the functional complementation analysis by somatic cell hybridization and confirmed by mutation screening showing a homozygous deletion of exon 43 (4267-4404del) in the FAA gene to be present in all four patients. The newborn patients had been diagnosed prenatally by DNA analysis. In spite of identical molecular pathology and close familial relationship the clinical phenotypes of the four patients were not concordant. Discordant symptoms included birthweight, pigmentation abnormalities, skeletal, renal and genital abnormalities, whereas microcephaly and possibly the haematological course were concordant. Differences in environmental conditions and/or genetic make-up along with chance effects during development may explain discordant phenotypes despite identical molecular pathology in these patients. However, our results do not rule out the possibility that the exon 43del mutation may have prognostic value for the haematological course of the disease.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/23. Paternal sex chromosome aneuploidy as a possible origin of turner syndrome in monozygotic twins: case report.The meiotic or mitotic origin of most cases of turner syndrome remains unknown, due to the difficulty in detecting hidden mosaicisms and to the lack of meiotic segregation studies. We have had the opportunity to study one pair of monozygotic twins concordant for turner syndrome of paternal origin. The paternal origin of the single x chromosome was determined by polymerase chain reaction (PCR) amplification. No mosaicism was detected for the X or y chromosome. In this case, a meiotic error during gametogenesis would be a likely origin of X monosomy. To determine if meiotic errors are more frequent in the father of these monozygotic twins concordant for turner syndrome of paternal origin, molecular studies in spermatozoa were conducted to analyse sex chromosome numerical abnormalities. A total of 12520 sperm nuclei from the twins' father and 85338 sperm nuclei from eight normal donors were analysed using three-colour fluorescent in-situ hybridization. There were significant differences between the twins' father and control donors for XY disomy (0.22 versus 0.11%, P < 0.001) and total sex chromosome disomy (0.38 versus 0.21%, P < 0.001). These results could indicate an increased tendency to meiotic sex chromosome non-disjunction in the father of the Turner twins.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/23. Analysis of a de novo complex chromosome rearrangement involving chromosomes 4, 11, 12 and 13 and eight breakpoints by conventional cytogenetic, fluorescence in situ hybridization and spectral karyotyping.A complex chromosome rearrangement (CCR) with eight breakpoints resulting in four derivative chromosomes (4, 11, 12 and 13) was detected prenatally in a male fetus of a twin pregnancy. The karyotype of the female second fetus was normal. The apparently balanced de novo CCR was identified by classical cytogenetic methods and fluorescence in situ hybridization (FISH). We compared these findings with results from spectral karyotyping (SKY).- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
4/23. Molecular tracking of leukemogenesis in a triplet pregnancy.The occurrence of childhood acute lymphoblastic leukemia (ALL) in 2 of 3 triplets provided a unique opportunity for the investigation of leukemogenesis and the natural history of ALL. The 2 leukemic triplets were monozygotic twins and shared an identical, acquired TEL-AML1 genomic fusion sequence indicative of a single-cell origin in utero in one fetus followed by dissemination of clonal progeny to the comonozygotic twin by intraplacental transfer. In accord with this interpretation, clonotypic TEL-AML1 fusion sequences could be amplified from the archived neonatal blood spots of the leukemic twins. The blood spot of the third, healthy, dizygotic triplet was also fusion gene positive in a single segment, though at age 3 years, his blood was found negative by sensitive polymerase chain reaction (PCR) screening for the genomic sequence and by reverse transcription-PCR. Leukemic cells in both twins had, in addition to TEL-AML1 fusion, a deletion of the normal, nonrearranged TEL allele. However, this genetic change was found by fluorescence in situ hybridization to be subclonal in both twins. Furthermore, mapping of the genomic boundaries of TEL deletions using microsatellite markers indicated that they were individually distinct in the twins and therefore must have arisen as independent and secondary events, probably after birth. These data support a multihit temporal model for the pathogenesis of the common form of childhood leukemia.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/23. Selective termination of aneuploidy utilizing rapid fluorescence in situ hybridization detection techniques.Twin pregnancy following assisted reproductive technology with a euploid fetus and a coexisting aneuploid co-twin constitutes a conflicting situation; therefore, it is important for the genetic constitution of each co-twin to be diagnosed accurately and promptly for parental genetic counseling and subsequent aggressive management. A 35-year-old woman, gravida 1, with a 2-year history of infertility, presented bilateral fallopian tubal obstruction at her infertility workups, for which she received in vitro fertilization; subsequently she conceived a twin pregnancy. She underwent genetic amniocentesis at 16 weeks' gestation, as indicated by an advanced maternal age. Presented with the diagnosis of twin pregnancy with discordancy for trisomy 21, a rapid fluorescence in situ hybridization (FISH) technique for aneuploidy mapping was applied for subsequent abdominal selective fetal reduction. The FISH technique facilitates the rapid analysis of uncultured amniocytes. Normal (disomic) and trisomic samples can be distinguished clearly and rapidly for subsequent selective fetocide. The FISH technique is an important tool in prenatal diagnosis and clinical applications.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
6/23. Secondary acute myeloid leukaemia with monosomy 7 in identical adult twins.We report the development of secondary acute myeloid leukaemia (AML) with monosomy 7 in identical twins, both at the age of 52 years. In the first twin, induction therapy resulted in complete remission (CR). At relapse 9 months later monosomy 7 was found. The patient died of sepsis 11 months after diagnosis. The other twin presented with leucopenia and thrombocytopenia and refractory anaemia (RA) was diagnosed. During follow-up, fluorescence in situ hybridization analysis demonstrated a monosomy 7 in 11% of the cells. Twenty-eight months following diagnosis the patient progressed to RA with excess blasts in transformation and induction chemotherapy was initiated without achieving CR. Three months later an allogeneic stem cell transplantation from a niece was performed, resulting in CR of the secondary AML.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
7/23. Monozygotic twins with discordant sexual phenotypes due to different ratios of mosaicism of 47,X,idic(Y),idic(Y)/46,X, idic(Y)/45,X.We report monozygotic twins of different sexual phenotypes. One of the twins had complete female external genitalia except for a mild clitoromegaly. She had bilateral gonads consisting of the wavy stroma and scant dysgenetic seminiferous tubules. No androgen secretion was induced by gonadotrophin stimulation. The other twin had hypospadiac male genitalia. His gonads were located intrascrotally and he had good androgenic response to a stimulation test. Conventional and fluorescence in situ hybridization chromosome analysis disclosed that both twins had a 47,X,idic(Y),idic(Y)/46,X,idic(Y)/45,X and 47,X, mar x 2.ish idic(Y)(q11.2)(DYZ3 x 2)/46,X, mar.ish idic(Y)(q11.2)(DZY3 )/45,X. These twins were clinically monochorionic and allelotype analysis in these twins and their parents with microsatellite markers showed the affirmative probability of 0.999999994 for monozygosity. The ratio of mosaicism, gonadal histology, and testosterone productivity were reasonably correlated to the genital virilization in these monozygotic twins, showing discordant sexual phenotypes.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
8/23. Prenatal chromosomal diversification of leukemia in monozygotic twins.Previous studies on concordant acute lymphoblastic leukemia (ALL) in identical twins have identified the leukemia as monoclonal with MLL or ETV6-RUNX1 gene fusion as early or initiating events in utero. In the latter case, postnatal latency is associated with secondary genetic events such as ETV6 deletion. We describe here a pair of infant twins with concordant acute monoblastic leukemia (AML). They are a unique pair in that their leukemia blasts display extensive intraclonal chromosomal diversity. Comparison of the leukemic cells between the two twins by karyotype and fluorescence in situ hybridization identifies a common or shared stem line and extensive subclonal diversity for which the twins' leukemic populations are divergent. This case of leukemia illustrates in utero initiation with early imposition of chromosomal instability, the progressively divergent evolution of which can be mapped in the twins into pre- and postnatal periods.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
9/23. Idiopathic hypertrophic cardiomyopathy in identical twins. Morphological heterogeneity of the left ventricle.We report a pair of identical twins with HC with varying extent of left ventricular hypertrophy and some degree of left ventricular outflow tract obstruction. The diagnosis of identical twins was based on the same sex, blood typings, HLA typings and hybridization patterns to four hypervariable dna probes. Identical twins are derived from a single zygote and are genetically homogeneous human beings. The present report suggests that heterogeneity in the morphologic expression of HC may not be solely attributed to genetic factors. Environmental factors also may play an important role.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
10/23. Differential clinical manifestations of congenital cytomegalovirus infection between dizygotic twins: a case report.To understand a mechanism for the difference in clinical manifestations of congenital cytomegalovirus (CMV) infection between dizygotic twins, the placentas of the dizygotic twins were evaluated for the number of the cells infected with CMV by immunohistochemical and in situ hybridization studies. A Japanese woman with dizygotic twin pregnancy had immunoglobulin m antibodies to CMV at 15 weeks gestation. Intrauterine growth retardation was noted only in the first twin. At birth, CMV was isolated from urine culture in both twins. Clinical manifestations for CMV, such as petechiae, jaundice, hepatosplenomegaly, and deafness were more pronounced in the first twin than in the second twin. Immunohistochemical and in situ hybridization studies showed CMV-positive cells two or three times more densely distributed in the placenta of the first twin compared with the second twin. These data suggest the severity of CMV manifestations of dizygotic twins may be in accord with the number of CMV-positive cells in the placenta.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |
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