RESUMO
A balanced whole arm translocation (1;19)(p10;q10) was found in a woman with normal phenotype ascertained through a fragile X survey. Chromosome painting with the specific libraries confirmed the cytogenetic diagnosis. Fluorescence in situ hybridization with a chromosome-1 alpha-satellite probe revealed that the breakpoint in chromosome 1 split the alpha-satellite sequences into two blocks. The review of constitutional whole arm translocations revealed a greater participation of some chromosomes with recurrence of translocations t(1;19)(1p19q;1q19p), t(18;20)(18p20q;18q20p) and t(X;17)(Xp17q;Xq17p). The alpha-satellite breakage documented in some derivatives of the recurrent translocations may be related to highly homologous subsets in the involved chromosome pairs, which belong to alpha-satellite subfamilies 1, 2 and 3 respectively. Probably this leads to abnormal chromosome pairing and thus to whole arm translocations.
Assuntos
DNA Satélite/genética , Síndrome do Cromossomo X Frágil/genética , Feminino , Humanos , Cariotipagem , Translocação GenéticaRESUMO
A boy of 16 months of age with psychomotor retardation, short stature, microbrachycephaly, triangular face, microphthalmia, palpebral fissures slanted downward, cardiopathy, simian crease on left hand, agenesis of fourth finger on the right hand and of the nail in the second finger on the right one was studied. The karyotype showed a complement of 46, XY, del(6) (q16.2q22.2). The clinical and cytogenetic analysis with other previous cases described in the literature led us to identificate other patients with ectrodactyly. Therefore as other authors we suggest the possible localization of gene(s) that could have involvement with the development of extremities in this segment.
Assuntos
Anormalidades Múltiplas/genética , Deleção Cromossômica , Cromossomos Humanos Par 6 , Deformidades Congênitas da Mão/genética , Humanos , Lactente , Cariotipagem , Masculino , SíndromeRESUMO
Balanced Y;Autosome translocations seem to be associated with male infertility whenever the Y breakpoint is located into Yq11 (where the azoospermia factor maps) or near its boundaries. By analogy with the effect on female carriers' fertility of balanced X;Autosome translocations, the band Yq11 emerges as the critical segment. This hypothesis implies that the subjacent mechanism is an impaired expression of the azoospermia factor--either through its physical disruption or via a position effect--rather than a disorder of the sex bivalent inactivation during prophase I.
Assuntos
Infertilidade Masculina/genética , Translocação Genética , Cromossomo Y/ultraestrutura , Humanos , Masculino , Modelos GenéticosRESUMO
An azoospermic male with a 46,X,t(Y;19)(q12;q13) karyotype is described. The comparison with 12 similar cases reveals that the Y breakpoints are usually on the long arm whereas the autosomal ones seem to be at random. Since a premeiotic origin is inconsistent with the arrest at diakinesis seen in those cases with meiotic studies, we postulate that a balanced t(Y;A) arises either via a chromatid exchange in the meiotic interphase or through a chromosome exchange in spermiogenesis or at the one cell stage of the zygote.
