Delineation of an Isodicentric Y Chromosome in a Mosaic 45,X/46,X,idic(Y)(qter-p11.3:: p11.3-qter) Fetus by SRY Sequencing, G-banding, FISH, SKY and Study of Distribution in Different Tissues (original) (raw)
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Fertility and Sterility, 2008
Objective: To determine the clinical implications of the presence of a Y chromosome in Turner's syndrome patients with karyotype abnormalities. Design: To investigate the presence of Y-chromosome sequences in different tissue samples. Setting: Endocrinology outpatient clinic of a federal university in Brazil. Patient(s): Five Turner's syndrome patients with karyotype abnormalities such as marker chromosomes, additional material, or ring chromosomes. Intervention(s): Peripheral blood, oral epithelial cells, and hair root samples were collected. Main Outcome Measure(s): The SRY gene and the DYZ3 repeat region were amplified by polymerase chain reaction followed by gel electrophoresis mobility of amplified genomic DNA, and ultraviolet visualization. Prophylactic gonadectomy was offered to the Y-positive patients.
European Journal of Obstetrics & Gynecology and Reproductive Biology, 2004
Objective: To investigate the presence of mutations in the open reading frame (ORF), as well as on the 5 0 and 3 0 , flanking regions of the SRY gene in patients with mixed gonadal dysgenesis (MGD) or with Turner syndrome (TS) and Y mosaicism. Study design: We studied 13 patients with MGD and three patients with TS and Y mosaicism. DNA was isolated from blood leukocytes for subsequent polymerase chain reaction (PCR) and direct sequencing were performed in the ORF, as well as from the 5 0 and 3 0 flanking regions of the SRY gene. Results: No mutations were present in any of the patients studied. Conclusion: The absence of mutations in these regions indicated that mutations were an unlikely cause of MGD or TS with Y mosaicism and suggested that there are others genes playing an important role in sex development.
Genetic considerations in the patient with Turner syndrome—45,X with or without mosaicism
Fertility and Sterility, 2012
Turner syndrome (TS) is a complex developmental disorder in individuals with short stature who possess a 45,X cell line, with or without mosaicism. Because the single X chromosome is maternally derived in 80% of patients, the genesis of the 45,X karyotype is due to instability of the Y chromosome leading to its loss during meiosis. Phenotypic features vary depending on the mode of ascertainment, with postnatal presentation usually generating a more severe phenotype than a prenatal one. Although patients with pure 45,X present with delayed puberty more often than those with mosaicism for 46,XX or 47,XXX cell lines, the chromosomal complement cannot reliably predict the clinical presentation. Most living TS patients are mosaics, whereas nearly all first-trimester TS fetuses have a single 45,X cell line. Exclusion of a Y cell line, the presence of which increases the risk of gonadoblastomas and subsequent gonadal germ cell tumors, is best accomplished by karyotype, fluorescence in situ hybridization, and DNA analysis if necessary. The precise genetic etiology of TS has not been elucidated, but it does appear that deletion of the short arm of the X chromosome is sufficient to result in the TS phenotype, thereby implicating haploinsufficiency of multiple genes, including SHOX.
A female patient with a structurally abnormal idic(Y) (p11.32) chromosome was studied using fluorescence in situ hybridiza-tion and PCR to define the precise position of the breakpoint. The patient had a complex mosaic karyotype with eight cell lines and at least two morphologically distinct derivatives from the Y chromosome. The rearrangement was a result of a meiosis I exchange between sister chro-matids at the pseudoautosomal region, followed by centromere misdivision at meiosis II. Due to instability of the dicentric Y chromosome, new cell lines later arose because of mitotic errors occurring during embryonic development. Physical examination revealed a normal female phenotype without genital ambiguity, a normal uterus and rudimentary gonads which were surgically removed.