Trisomy 15 mosaicism: Challenges in prenatal diagnosis

Silva, Marisa; Alves, Cristina; Pedro, Sónia; Marques, Bárbara; Ferreira, Cristina; Furtado, José; Martins, Ana Teresa; Fernandes, Rosário; Correia, Joaquim; Correia, Hildeberto

http://hdl.handle.net/10400.18/3355

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
1f2657ce171d606ce7f73f0770ce3f7a6961cf9103f761c0d9bf5bc136b82186.pdf	Silva M et all_Trisomy 15 mosaicism: Challenges in prenatal diagnosis	423.66 KB	Adobe PDF	Download

Send Feedback

Authors

Abstract(s)

Trisomy 15 mosaicism (mosT15) has been described in fetuses and live-born infants [Christian et al., 1996; Redaelli et al., 2005], with most cases involving confined placental mosaicism (CPM) and meiotic non-disjunction (ND) [EUCROMIC, 1999]. Poor pregnancy outcome prognosis is associated with the presence of aneuploid cells, and there is also a risk of uniparental disomy 15 (UPD15) due to correction of the trisomic state to a disomic constitution. Trisomy or monosomy rescue, gamete complementation and postfertilization error are the main mechanisms leading to UPD and may cause heterodisomy (heteroUPD), isodisomy (isoUPD) or both, depending on the number of meiotic recombinations. The result of maternal (matUPD) and paternal (patUPD) UPD15 is Prader–Willi and Angelman syndrome, respectively, due to imprinting of chromosome region 15q11–15q13. UPD detection can only be achieved using molecular methodologies, such as methylation-specific assays (MSA) [Kotzot, 2008] and, more recently, genome-wide single nucleotide polymorphism (SNP) arrays [Conlin et al., 2010; Schroeder et al., 2013]. MSA allow for methylation pattern analysis of the chromosome regions of interest and SNP-arrays may provide information about copy number as well as UPD, in cases of isoUPD or isodisomy secondary to recombination. HeteroUPD may also be diagnosed by SNParrays if parental and proband DNAs are analyzed in a trio [Conlin et al., 2010; Schroeder et al., 2013]. However, not all molecular methods are equally informative and when a mosaicism is present, especially in a prenatal setting, parent-of-origin analysis as well as karyotype–phenotype correlations become quite challenging. Here we report on a fetus with a CVS diagnosed mosT15 with different degrees of mosaicism found in different tissues and briefly discuss the challenges of prenatal diagnosis of UPD15. (...)