RESUMO
X/X translocations are quite rare in humans. The effect of this anomaly on the phenotype is variable and depends on the amount of deleted material and whether the chromosomes are joined by their long or short arms. We report an unusual case of Turner syndrome mosaicism in a 16-year-old girl, who was referred to our Institute for primary amenorrhoea associated with short stature. Endocrine evaluation revealed hypergonadotropic hypogonadism, which required a study of the karyotype. Cytogenetic analysis, performed on peripheral blood leucocytes, showed a mos 45,X/46,X,ter rea (X;X)(p22.3;p22.3) de novo karyotype. The prevalent cell line was 45,X (90% cells). A second cell line (10% cells) showed a very large marker chromosome, similar to a large metacentric chromosome. FISH (fluorescent in situ hybridisation) and molecular analysis revealed that the marker chromosome was dicentric and totally derived from the paternal X chromosome.
Assuntos
Amenorreia/genética , Aberrações Cromossômicas , Cromossomos Humanos X/genética , Período Pós-Parto/genética , Síndrome de Turner/genética , Adolescente , Feminino , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Mosaicismo , Proibitinas , Receptores AndrogênicosAssuntos
Duplicação Cromossômica , Cromossomos Artificiais Bacterianos , Hibridização Genômica Comparativa , Epilepsia/genética , Mosaicismo , Cromossomos em Anel , Adolescente , Anticonvulsivantes/uso terapêutico , Cromossomos Humanos Par 20 , Resistência a Medicamentos , Epilepsia/tratamento farmacológico , Feminino , Predisposição Genética para Doença , Humanos , Fenótipo , SíndromeRESUMO
We describe the first case of mosaic supernumerary marker iso (8p) displaying a karyotype discordance between chorionic villi (CV) and amniotic fluid (AF) cultures during prenatal cytogenetic diagnosis. In the first trimester, cytogenetic analysis after chorionic villi sampling (CVS) was normal in all metaphases in the short-term cytotrophoblast cell culture, but an undefined supernumerary marker was detected in 60% of mesenchymal cells in the long-term CV culture. Informed of the mosaicism, the couple selected amniotic fluid sampling as a second-trimester confirmatory diagnostic procedure. The supernumerary marker was absent in all of the 25 available AF cells metaphases. The prospective parents received genetic counselling and were informed that the discordance could be interpreted as a placental confined mosaicism or as a true foetal mosaicism with low percentage of affected cells. The couple opted to continue the pregnancy. In the second month of life, the child had abnormal development with severe psychomotor delay and frequent episodes of epilepsy. Postnatal cytogenetic extensive re-evaluation discovered that the previously detected supernumerary marker was indeed an isochromosome (8p) rearrangement present at low frequency in 5% of the blood lymphocytes.