Browsing by Author "Lamar Segura, Elizabeth"

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Multi-institutional experience of genetic diagnosis in Ecuador: national registry of chromosome alterations and polymorphisms
(2020) Paz y miño Cepeda, Cesar Antonio; Yumiceba Corral, Veronica Patricia; Moreta Duque, Germania de los Ángeles; Paredes Borja, Rosario; Llamos Paneque, Arianne; Ochoa Pérez, Angela Catalina; Ruiz Cabezas, Juan Carlos; Alvarez Vidal, Jenny Monserrat; Jiménez Torres, Idarmis; Vargas Vera, Ramón Miguel; Guapi N, Víctor Hugo; Montalvan, Martha; Menéses Alvarez, Sara; Garzón Castro, Maribel; Lamar Segura, Elizabeth
Background: Detection of chromosomal abnormalities is crucial in various medical areas; to diagnose birth defects, genetic disorders, and infertility, among other complex phenotypes, in individuals across a wide range of ages. Hence, the present study wants to contribute to the knowledge of type and frequency of chromosomal alterations and polymorphisms in Ecuador. Methods: Cytogenetic registers from different Ecuadorian provinces have been merged and analyzed to construct an open-access national registry of chromosome alterations and polymorphisms. Results: Of 28,806 karyotypes analyzed, 6,008 (20.9%) exhibited alterations. Down syndrome was the most frequent autosome alteration (88.28%), followed by Turner syndrome (60.50%), a gonosome aneuploidy. A recurrent high percentage of Down syndrome mosaicism (7.45%) reported here, as well as by previous Ecuadorian preliminary registries, could be associated with geographic location and admixed ancestral composition. Translocations (2.46%) and polymorphisms (7.84%) were not as numerous as autosomopathies (64.33%) and gonosomopathies (25.37%). Complementary to conventional cytogenetics tests, molecular tools have allowed identification of submicroscopic alterations regions or candidate genes which can be possibly implicated in patients' symptoms and phenotypes. Conclusion: The Ecuadorian National Registry of Chromosome Alterations and Polymorphisms provides a baseline to better understand chromosomal abnormalities in Ecuador and therefore their clinical management and awareness. This data will guide public policy makers to promote and financially support cytogenetic and genetic testing.
Turner syndrome associated with Down syndrome: about a case
(2022) Llamos Paneque, Arianne; Pozo Palacios, Juan Carlos; Sacan Jalca, Byron; Garzon Castro, Maribel de los Angeles; Lamar Segura, Elizabeth; Ñacato Pachacama, Karen Lizbeth
The coexistence of double aneuploidy of Down and Turner syndromes is rare; most cases have been due to double mitotic errors. The objective of the study was to report a case with monosomy of the X chromosome and trisomy of chromosome 21, in mosaic variety, highlighting the phenotypic effect that the presence of different chromosomal abnormalities can produce and compare with those reported in the literature. A 10-year-old Ecuadorian female, born to a multipregnant mother with 46 years at conception, is seen in consultation with a predominant clinical phenotype of Down syndrome, associated with menarche, presence of pubic and axillary villu, where a karyotype is verified 45 X[7]/47XX+ 21 [3]/46, X, der (X)(: p11.1-> q11.1)[1]/46,XX [1]. The present case is a double Turner-Down aneuploidy, with predominantly X monosomy cell line, who shows important mental retardation and some signs of puberal development not usually in Turner syndrome. These features highlight the clinical importance of doing a karyotype in mental retardation cases and searching low mosaics of another aneuploidies in atypical cases. Its complex chromosomal formula and support with molecular cytogenetics allowed diagnostic confirmation and genetic counseling.