Browsing by Author "Tarelho, A."
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- 47,XY,+del(X)(q21.31)/46,XY mosaicism in prenatal diagnosis - case report of a rare eventPublication . Ferreira, C.; Tarelho, A.; Marques, B.; Serafim, S.; Pedro, S.; Ferreira, A.; Correia, H.OBJECTIVES: Aneuploidies involving the sex chromosomes are the most common anomalies in humans. In many cases these anomalies are present in mosaic and may involve either the whole chromosome or just part of it. These anomalies constitute a challenge in prenatal diagnosis because it is generally very difficult to establish a reliable genotype-phenotype correlation. Here we report a rare event of a mosaic in which one cell line carries an additional abnormal X chromosome, with a terminal deletion at q21.31 region, and a normal XY constitution in the majority of the cells. METHODS: A healthy 36-year-old G1P1 woman was referred for prenatal diagnosis at 11+5 weeks of gestation for increased nuchal translucency. Chorionic villus biopsy was performed and molecular rapid aneuploidy result indicated an anomalous situation for the X chromosome in a male fetus. As the material was not sufficient to establish a culture an amniocentesis was performed at 17+3 weeks and karyotyping and microarray were performed in order to characterize the anomalous result. RESULTS: The results obtained indicated the presence of a mosaic involving an extra X chromosome with a terminal deletion, [47,XY,+del(Xq)/46,XY.arr[GRCh37] Xp22.33q21.31(169921_89283237)x1~2], which is compatible with a Klinefelter syndrome variant. CONCLUSIONS: Pregnancies affected by X chromosome aneuploidies diagnosed prenatally are at an increased risk of adverse fetal and neonatal outcomes. High quality information is critical for informed decision-making in pregnancy following a prenatal diagnosis of sex chromosome aneuploidy. The participant shall be able to understand the importance of breakpoints definition and the impact that a mosaicism situation have in prenatal diagnosis.
- Classification of the dup 15q13.3 CNV: A National data collectionPublication . Sousa, A.; Serafim, S.; Santos, R.; Custódio, S.; Ávila, M.; Dupont, J.; Dias P, P.; Moldovan, O.; Melo, J.; Ferreira, S.; Pires, L.; Leão, M.; Sá, S.; Prior, C.; Alves, C.; Barreta, A.; Tarelho, A.; Marques, B.; Pedro, S.; Lopes, F.; Maciel, P.; Correia, H.; Dória, S.; Rendeiro, P.; Castedo, S.; Carreira, I.; Sousa, A.B.Introduction: The proximal region 15q11q14 is one of the most unstable regions in the human genome, with six recognizable break points (BP1-BP6). In 15q13.3 there is a recurrent small CNV (BP4-BP5) consisting of a 350-680 Kb duplication, encompassing the CHRNA7 gene, which encodes the alpha 7 subunit of the neuronal nicotinic acetylcholine receptor. Although microdeletions of CHRNA7 are known to cause intellectual disability and neuropsychiatric phenotypes with high penetrance, the patogenicity of CHRNA7 duplications remains unclear. Microduplication 15q13.3 seems to be associated with a phenotypic spectrum of cognitive impairment and neuropsychiatric/neurobehavioral disorders. However, the penetrance of this CNV is considered incomplete since it is present in clinically unaffected individuals in the general population and it is frequently inherited from apparently clinically normal parents. Nonetheless, some pedigree studies have found a history of neuropsychiatric problems among carrier family members. This study aimed at re-evaluating the dup 15q13.3 CNV in national laboratories. Materials and Methods: Our study collected data on 15q13.3 microduplications in eight Portuguese genetics laboratories, among subjects referred for microarray. Results: Here we present a total of seventeen cases with dup 15q13.3. The subjects had somewhat variable phenotypes, with a bias towards developmental delay and autism spectrum disorders. Inheritance was established for eight of the subjects, and the majority originated from the father. We had no access to clinical data on carrier parents. No de novo CNV was found. All laboratories involved classified this variant as of uncertain significance. Discussion/Conclusion: To better determine whether this CNV is benign or pathogenic, careful characterization of patient and control cohorts must be performed, including detailed patient phenotyping, inheritance, clinical evaluation of carrier parents, prevalence in controls, as well as genetic functional studies. We strongly support the creation of a national database for uncertain CNVs in order to clarify the relevance of these recurrent findings, allowing a definitive classification in either pathogenic or benign.
- Prenatal diagnosis of mosaic ring chromosome 16 - a rare event with uncertain prognosisPublication . Brito, F.; M. Silv, M.; Alves, C.; Ferreira, C.; Serafim, S.; Simão, L.; Marques, B.; Pedro, S.; Tarelho, A.; Furtado, J.; Lopes, P.; Silva, N.; Viegas, M.; Fernandes, A.; Teixeira, F.; Gomes, S.; Correia, H.Ring chromosomes are rare cytogenetic findings (prenatal frequency ~ 0.0075%) often associated with an abnormal phenotype, depending of the chromosomal origin, genetic content and the presence of a mosaic. Supernumerary ring chromosome 16 [r(16)] is rarely observed and mosaicism makes the genotype/phenotype correlation difficult. We report a de novo mosaic r(16) detected after prenatal diagnosis in a woman referred for advanced maternal age. Multiplex ligation-dependent probe amplification (MLPA) for aneuploidy testing of chromosomes 13, 18, 21 and X was normal. Karyotype was 47,XX,+r[10]/46,XX[15]. Chromosomal microarray analysis (CMA) on DNA obtained from long-term cultured amniocytes did not detect any alterations. MLPA with a pericentromeric probe kit on an uncultured sample showed a chromosome 16 gain, encompassing 16p11.2 and 16q11.2 regions, including TGFB1I1, AHSP, VPS35 and ORC6 genes, leading to partial characterization of the r(16). Although no phenotype has been correlated with overexpression of these genes, the 16p11.2 region is associated with neurodevelopmental disorders. Nevertheless individuals with microduplication of 16p11.2 and normal development have been described. The lack of a precise definition of genetic content of the r(16) and its mosaic form leads to uncertain prognosis of clinical outcome.