Browsing by Author "Amorim, Marta"
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- A 669Kb deletion in 17q23.2, encompassing TBX2 and TBX4 genes, in a girl with a moderate developmental delay without any other pertinent abnormalityPublication . Ferreira, Cristina; Marques, Bárbara; Pedro, Sónia; Serafim, Silvia; Amorim, Marta; Correia, HildebertoMicrodeletion of the 17q23.1-q23.2 region recently emerged as a syndrome (OMIM#613355) based in a small number of cases with a common phenotype including mild-to-moderate developmental delay, heart defects, microcephaly, postnatal grow retardation, and hand, foot, and limb abnormalities. All patients reported to date present mild to moderate developmental delay, in particular speech delay, and half of them hearing loss. The smallest overlapping region has approximately 2.2 Mb and includes the transcription factors TBX2 and TBX4 genes. These genes have been implicated in a number of developmental pathways, including those of the heart and limbs. The TBX4 gene is also associated with the autosomal dominant small patella syndrome (SPS, OMIM 147891). Here we report a 8 year-old girl with moderate developmental delay including learning disabilities. The test for Fragile X syndrome indicated an allele within the grey area (number of repeats ~50 CGG) inherited from her mother and probably not relevant. Affymetrix Cytoscan HD chromosome microarray analysis was performed and a 669 Kb interstitial deletion was detected at 17q23.2 region, encompassing only five OMIM genes: BCAS3, TBX2, TBX4, NACA2 and BRIP1. To our knowledge this is the smallest deletion described in this region. None of the genes present in the deleted region are known to be associated with developmental problems. We compare our patient with the other similar reported cases, in order to add some increased value to the phenotype-genotype correlation of deletions in this region.
- Incidental X Linked Findings A female fetus with a gain in the DMD genePublication . Marques, Bárbara; Serafim, Silvia; Pedro, Sónia; Ferreira, Cristina; Simão, Laurentino; Alves, Cristina; Viegas, Mónica; Silva, Marisa; Brito, Filomena; Amorim, Marta; Correia, Joaquim; Correia, HildebertoIn prenatal diagnosis, chromosomal microarray analysis (CMA) has not yet fully replaced conventional cytogenetic but has rapidly become the recommended genetic test in pregnancies with ultrasound abnormalities. This methodology allows the identification of pathogenic small copy number variation (CNVs) in 5-10% of pregnancies with ultrasound abnormalities and a normal karyotype, increasing the diagnostic yield. However, this increased resolution can also result in the detection of incidental findings. Here we report a fetus referred for prenatal diagnosis due to skeletal dysplasia. Affymetrix Cytoscan HD chromosome microarray analysis was performed and a 204 kb gain was detected at Xp21.1 region (chrX: 31993622_32191110 [GRCh37]) in a female fetus, encompassing the intron 44 of the DMD gene, for the largest gene transcript. Nevertheless, if we considered the smaller transcripts it encompasses exon 1. The gain was maternally inherited. The DMD gene is involved on Becker muscular dystrophy, Cardiomyopathy, dilated, 3B and Duchenne muscular dystrophy. Intron 44 is a preferential breakpoint in about 30% of all DMD deletions, being the DMD transcript NM_004006.2 responsible for dystrophin expression in the skeletal muscle.The FGFR3 gene sequencing revealed the presence of the c.1118A >G, p.Y373C mutation associated to Thanatophoric Dysplasia, type 1 (TD1) justifying the ultrasound abnormalities.With this case, we reinforce that the discovery of CNVs in prenatal CMA goes beyond the correlation with the CNV and the ultrasound abnormalities. Incidental findings can also have a larger impact to the family clinical managing, even if not for the ongoing pregnancy for the reproductive future of the couple.
- Molecular characterization of a rare analphoid supernumerary marker chromosome derived from 7q35 → qter: a case reportPublication . Marques, Bárbara; Ferreira, Cristina; Brito, Filomena; Pedro, Sónia; Alves, Cristina; Lourenço, Teresa; Amorim, Marta; Correia, HildebertoBackground: Analphoid supernumerary marker chromosomes (aSMC) constitute one of the smallest groups of SMC, and are characterized by a centromeric constriction but no detectable alpha-satellite DNA. These marker chromosomes cannot be properly identified by conventional banding techniques alone, and molecular cytogenetic methods are necessary for a detailed characterization. Analphoid SMC derived from chromosome 7 are extremely rare, with only five cases reported so far. Case presentation: In this work we report an aSMC involving the terminal long arm of chromosome 7 in a 10-year-old boy with multiple dysmorphic features and severe development delay. Cytogenetic analysis revealed a mosaic karyotype with the presence of an extra SMC, de novo, in 20% of lymphocytes and 73% of fibroblast cells. Next, we performed FISH analysis with multiple DNA probes and cCGH analysis. This identified the origin of the SMC as an analphoid marker resulting of invdup rearrangement of 7q35-qter region. Affimetrix CytoScan HD array analysis redefined the aSMC as a 15.42 Mb gain at 7q35-q36.3 (minimum tetraplicated region-chr7: 143,594,973-159,119,707; GRCh37/hg19) of maternal origin that encloses 67 OMIM genes, 16 of which associated to disease. Uniparental disomy of chromosome 7 (UPD 7) has been excluded. Conclusions: We report the first patient with an aSMC(7) derived from the terminal 7q region who has been molecularly and clinically full characterized. The use of SNParray in the characterization of SMC reveals to be a powerful tool, giving information not only about copy number variation but also about loss-of-heterozygosity and parental origin. We conclude that an integrated genome-wide copy number variation analysis, if possible associated to FISH and gene expression studies, could facilitate in the future the difficult task of establishing accurate genotype-phenotype correlations and help to improve genetic counselling.