PubMed Health⌕ Search

Biomedical subjects

Helen Lawce

Publications and source records attributed to Helen Lawce.

6 recordsLinked to original sources
PubMed2005

Y chromosome heterochromatin of differing lengths in two cell populations of the same individual.

OBJECTIVE: To present a prenatal diagnosis report on a case where G-banding analysis of fetal metaphase chromosomes showed populations of cells with two different Y chromosomes; one with a short block of heterochromatin (Yqh-) and one with a longer block of heterochromatin (Yqh+). METHODS: These two populations of the Y chromosome were studied using fluorescent quinacrine banding and fluorescent in situ hybridization (FISH). A chromosome paint corresponding to the euchromatic region of the Y chromosome, and probes corresponding to the SRY, DYZ1, and DYZ3 regions were used for this study. RESULTS: Both Y chromosomes appeared to be structurally normal by these analyses. Subsequent ultrasound examination at 20 weeks' gestation revealed normal male genitalia. Follow-up with a neonatal blood sample analysis confirmed the above findings. CONCLUSIONS: This study reports a direct prenatal diagnosis case of two populations of the Y chromosome in the same individual. This apparent mosaicism may be explained by a postzygotic simple deletion or unequal crossover event between sister chromatids in the DYZ region.

Adult↗
PubMed2005

Trisomy 8 as the sole cytogenetic abnormality in a case of extraskeletal mesenchymal chondrosarcoma.

Mesenchymal chondrosarcoma is a rare malignant tumor that comprises about 3-10% of all sarcomas. Reports of cytogenetic studies of mesenchymal chondrosarcoma are limited and no consistent cytogenetic abnormality has surfaced. Some mesenchymal chondrosarcomas have a t(11;22) translocation suggesting a relationship with the PNET/Ewing tumor family. We report what to our knowledge is the first case of trisomy 8 as the sole cytogenetic abnormality in a mesenchymal chondrosarcoma.

Child↗
PubMed2004

Myxoinflammatory fibroblastic sarcoma with complex supernumerary ring chromosomes composed of chromosome 3 segments.

Myxoinflammatory fibroblastic sarcoma is a rare, recently described, and distinctive low-grade tumor of soft tissue. To our knowledge, there is only one previous report on the cytogenetics of this tumor. That case showed complex structural abnormalities, including a reciprocal translocation between chromosomes 1 and 10 [t(1;10)(p22;q24)] with loss of chromosomes 3 and 13. We describe here a second case showing supernumerary ring chromosomes, and a derivative chromosome 13, with additional material on the short arm. We conclude that the presence of chromosomal abnormalities supports the neoplastic nature of this tumor and aids in its diagnosis. Furthermore, we also postulate that the finding of ring chromosomes, which have been identified in other low-grade soft-tissue tumors, may have important prognostic implications regarding the aggressiveness of this neoplasm.

Chromosome Aberrations↗
PubMed2004

The role for preimplantation genetic diagnosis in balanced translocation carriers.

OBJECTIVE: Preimplantation genetic diagnosis is an established technique that provides an alternative to prenatal diagnosis for patients who are at risk of transmitting a serious genetic disorder to their offspring. Preimplantation genetic diagnosis has been used for couples who have been at risk for having offspring with single gene or X-linked disorders and for screening for common age-related aneuploidy and in couples who themselves carry balanced chromosomal rearrangements. The aim of this study was to summarize our experience using preimplantation genetic diagnosis after the identification of a parental balanced translocation, specifically as it relates to the number of embryos that are suitable for transfer after preimplantation genetic diagnosis for a known translocation and aneuploidy screening. STUDY DESIGN: This is a retrospective review of data from a single center that involved 6 couples that initiated the process of preimplantation genetic diagnosis for translocation and aneuploidy screening by fluorescent in situ hybridization. RESULTS: A total of 65 embryos were obtained, of which 56 embryos (86%) were suitable for fluorescent in situ hybridization analysis. After fluorescent in situ hybridization, 1 embryo was diagnosed as normal or balanced (1.7%). Forty-three embryos (76.8%) were unbalanced for the translocation; 8 embryos (14.3%) were aneuploid, and 4 embryos (7.1%) were uninformative. There were no clinical pregnancies. CONCLUSION: In our experience, there are very few embryos that are available for transfer from these patients after translocation and aneuploidy screening because of multiple unbalanced segregation products and a high rate of aneuploidy. Factors that contributed to this may be related to which parent carries the translocation, methods that were used for in vitro fertilization, and advanced maternal age. Although preimplantation genetic diagnosis for translocation carriers theoretically can enhance the pregnancy rate for a couple, there are limitations. This information should be shared with couples who are contemplating preimplantation genetic diagnosis for translocation, and the options of sperm or egg donor should be considered.

Adult↗