1/19. Meiotic origin of trisomy in neoplasms: evidence in a case of erythroleukaemia.Trisomic cells in neoplasms may represent abnormal clones originated from a tissue-confined mosaicism, and arise therefore by a meiotic error. We report on a 16-month-old child with erythroleukaemia (AML-M6), whose marrow karyotype at onset was 48,XX,del(13)(q12q14),del(14)(q22q32), 21, 21. The parental origin of the supernumerary chromosomes 21 was investigated by comparing 10 polymorphic loci scattered along the whole chromosome on the patient's marrow and her parents' leukocytes. Three loci were informative for the presence of three alleles, two of which were of maternal origin; two further loci showed a maternal allele of higher intensity. lymphocytes and skin fibroblasts showed a normal karyotype, and molecular analysis on leukocytes at remission, buccal smear and urinary sediment cells consistently showed only one maternal allele, whereas neonatal blood from Guthrie spot showed two maternal alleles as in the marrow. An accurate clinical re-evaluation confirmed a normal phenotype. Our results indicate that tetrasomy 21 arose from a marrow clone with trisomy 21 of meiotic origin. To the best of our knowledge, this is the first evidence that supernumerary chromosomes in neoplastic clones may in fact be present due to a meiotic error. This demonstrates that a tissue-confined constitutional mosaicism for a trisomy may indeed represent the first event in multistep carcinogenesis.- - - - - - - - - - ranking = 1keywords = trisomy (Clic here for more details about this article) |
2/19. Constitutional trisomy 8 mosaicism due to meiosis II non-disjunction in a phenotypically normal woman with hematologic abnormalities.Constitutional trisomy 8 mosaicism (CT8M) in liveborns is typically caused by mitotic non-disjunction and exhibits wide phenotypic variability. By contrast, CT8M due to meiotic errors usually results in miscarriage. We describe a case of CT8M due to a paternal meiosis II non-disjunction error. The patient, a 32-year-old woman, was phenotypically normal except for a history of recurrent aphthous ulcers since childhood and a 4-year history of macrocytosis. The ulcers were refractory to steroids, but responded well to thalidomide. To the best of our knowledge, this is the first report of CT8M due to meiotic non-disjunction in a phenotypically normal individual.- - - - - - - - - - ranking = 0.83333333333333keywords = trisomy (Clic here for more details about this article) |
3/19. Recurrent trisomy 21: four cases in three generations.Recurrent trisomy 21: four cases in three generations.While gonadal mosaicism can lead to recurrence of trisomy 21 (T21) for a single couple, the recurrence of free T21 in multiple members of a single pedigree has rarely been reported. We present an unusual pedigree with four cases of down syndrome (DS) with free T21 were born to four separate women related through three generations of one family. The mothers were aged 18, 21, 29, and approximately 30 years at the time of the births. Using microsatellite markers, we excluded most of chromosome 21, excepting two small regions within 21q11.1 and 21q22.3, as being shared among the mothers of the DS children. However, two members of the pedigree, including one DS mother with a normal G-banded karyotype, carried supernumerary alleles at markers 2503J9TG, D21S369, and D21S215, which span the region from 21pter to 21q11.1. fluorescence in situ hybridization using a centromeric probe hybridizing to chromosomes 13 and 21 did not reveal a novel location, ruling out a cryptic centromeric translocation between chromosome 21 and any chromosome other than chromosome 13. The level of meiotic recombination on chromosome 21 was unusually high in this family as well. We hypothesize that a cryptic rearrangement within the highly repetitive region of 21q11.1 is present in this family, disrupting pairing and leading to an increased risk of non-disjunction of chromosome 21 in this family.- - - - - - - - - - ranking = 1keywords = trisomy (Clic here for more details about this article) |
4/19. The unbalanced offspring of the male carriers of the 11q;22q translocation: nondisjunction at meiosis II in a balanced spermatocyte.Carriers of the standard translocation t(11;22) (q23.3;q11.2) produce only one type of unbalanced offspring, a tertiary trisomy resulting into the karyotype 47,XX or XY, der(22)t(11;22)(q23.3;q11.2), usually derived from the mother. The exception is one single patient 47,XY,t(11;22)(q23.3;q11.2), der(22)t(11;22) (q23.3;q11.2)pat. We report a second case with the same karyotype, also of paternal origin. Thus, the rare unbalanced offspring of a carrier father (only 5 cases known) may receive a supernumerary der(22), as a consequence of tertiary trisomy, but also as a consequence of nondisjunction at meiosis II of a balanced spermatocyte.- - - - - - - - - - ranking = 0.33333333333333keywords = trisomy (Clic here for more details about this article) |
5/19. Free proximal trisomy 21 in the mother and malformation syndrome in the son.We report on a new case of duplication of the proximal part of the long arm of chromosome 21. The proposita presents normal mental development, no trisomy 21 manifestations; on the contrary, she had a few monosomy 21-like stigmata. She gave birth to a severely malformed infant with a pattern of malformations suggesting a partial 21-monosomy syndrome, but with a 46,XY normal karyotype in his peripheral blood lymphocytes. The findings are explained in the following way: the infant probably had originally a 47,XY, 21q- karyotype like his mother. Post zygotic nondisjunctional events produced a prevalent 46,XY,21q- line responsible for the severe malformations and the normal 46,XY line found in his blood lymphocytes.- - - - - - - - - - ranking = 0.83333333333333keywords = trisomy (Clic here for more details about this article) |
6/19. Nucleolar organizer region heteromorphism associated with trisomy-21: a risk factor for non-disjunction?An unusual nucleolar organizer region (double NOR) on chromosome 13 was observed in a down syndrome child [47, XY, 21, dNOR(13)]. The variant chromosome was inherited from the mother [46, XX, dNOR(13)]. The extra chromosome 21 in the proband was maternal origin. The frequency of NOR chromosome association showed relatively high frequency in the mother and proband as compared to the controls. The result suggest that chromosome variants involving extra copies of NOR may indeed be involved in the meiotic nondisjunction of chromosome-21.- - - - - - - - - - ranking = 0.66666666666667keywords = trisomy (Clic here for more details about this article) |
7/19. Cytogenetic and molecular studies of trisomy 13.Chromosome heteromorphisms, restriction fragment length polymorphisms, or both were used to study the parental origin of 33 cases of simple trisomy 13 and eight cases of translocation trisomy 13. The most common origin for the simple trisomies was non-disjunction at maternal meiosis I, while for the translocations an equal number of paternally and maternally derived cases was observed. In seven of the simple trisomies, information was obtained from both the cytogenetic and molecular markers, making it possible to study recombination between the two non-disjoined chromosomes. Five of the seven cases involved errors at meiosis I, with crossing over being detected in two of three cases of maternal origin and in one of two cases of paternal origin. This indicates that absence of recombination because of pairing failure is unlikely to be of major importance in the genesis of trisomy 13.- - - - - - - - - - ranking = 1.1666666666667keywords = trisomy (Clic here for more details about this article) |
8/19. Evidence for the repeated primary non-disjunction of chromosome 21 as a result of premature centromere division (PCD).A clinically normal 28-year-old woman had three conceptuses with trisomy 21 and one normal child. She showed minimal cytogenetic evidence of mosaicism: 4% of her blood cells and 6% of skin fibroblasts had trisomy 21. Also, 7% of her blood cells showed aneuploidy of the x chromosome which was associated with premature centromere division (PCD,X); 6% of fibroblasts showed trisomy 18, 10% of fibroblasts showed PCD,21, and 1% PCD,18. It is unlikely that this woman is a constitutional mosaic for trisomies X, 18, and 21, all at low levels. We suggest that she has a predisposition to irregular centromere separation and that chromosomes X, 18, and 21 are most susceptible to its action.- - - - - - - - - - ranking = 0.5keywords = trisomy (Clic here for more details about this article) |
9/19. Full trisomy 22 in a newborn infant.karyotype 47,XY, 22 was found in a newborn infant with primitive and low-set ears, bilateral preauricular pit, broad nasal bridge, antimongoloid palpebral fissures, macroglossia, enlarged sublingual glands, cleft palate, micrognathia, clinodactyly of the fifth fingers, hypoplastic finger nails, hypoplastic genitalia, short lower limbs, bilateral sandal gap and deep plantar furrows. The child developed signs of congenital heart disease and died at the age of 10 weeks. Non-disjunction studies showed maternal origin (meiosis I) of the extrachromosome.- - - - - - - - - - ranking = 0.66666666666667keywords = trisomy (Clic here for more details about this article) |
10/19. Duplication 8q24.2qter and 15q14 pter resulting from a 3:1 meiotic segregation of a maternal reciprocal translocation. We report on a 16-year-old female with duplication 8q24.2 qter and 15q14 pter resulting from a 3:1 segregation of a maternal balanced reciprocal translocation. This mode of unbalanced segregation could be predicted from Pachytene-diagram drawing. Most of her clinical manifestations can be related to the proximal 15q trisomy. To our knowledge there is only one previous report of a similar chromosome constitution.- - - - - - - - - - ranking = 0.16666666666667keywords = trisomy (Clic here for more details about this article) |
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