Browsing by Author "Duarte, Guida"
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- Alfa-talassémia delecional e fenótipo hematológico: parâmetros associados às diferentes deleções na casuística de 2015 a 2019Publication . Gaspar, Gisela; Ramalho, Rita de Mira; Seuanes, Filomena; Feliciano, Carla; Duarte, Guida; Copeto, Sandra; Costa, Alcina; Santos, João Xavier; Miranda, ArmandinaAs talassémias são caracterizadas por um desequilíbrio quantitativo nas cadeias globinicas devido à redução ou supressão da síntese de uma das cadeias. Foram avaliados retrospetivamente os resultados de 496 casos suspeitos de α-talassémia delecional e correlacionados com os dados hematológicos. A pesquisa de deleções causadoras de α-talassémia foi efetuada por Gap e Multiplex Gap-PCR. A maioria dos casos (n=190) apresentou um genótipo normal (αα /αα), seguido de heterozigotia (-α 3 ,7 /αα) (n=148) e homozigotia (-α 3 ,7 /α 3 ,7 ) (n=141) para a deleção de 3,7kb. Detetaram-se ainda 5 casos de heterozigotia para a deleção de 4,2Kb (-α 4,2 /αα), 4 de dupla heterozigotia ( α 3 ,7 /α 4,2 ), 7 de heterozigotia α 0 (-- S E A /αα ), e 1 de Hb H (-- S E A /-α 3 ,7 ). Os resultados evidenciaram que o VGM e o HGM são excelentes índices hematológicos de rastreio e seleção dos testes moleculares, sendo o seu valor tanto mais baixo quanto maior o número de genes delecionados. Os resultados obtidos são ainda concordantes com o descrito na literatura e reforçam que o valor de cut-off de 25 pg (HGM), tem sensibilidade adequada para inferir da presença de uma deleção α 0 -talassémia. A deteção da deleção α 0 assume particular importância na prevenção da ocorrência de Hb Bart’s na descendência de um casal de portadores. O diagnóstico de α-talassémia é efetuado por métodos moleculares, no entanto os índices hematológicos são importantes marcadores preditivos do número de genes alfa delecionados e da relação fenótipo / genótipo.
- A complex chromosomal rearrangement in a child with developmental delay, fractious behavior, and craniofacial anomalies, compatible with Smith-Magenis SyndromePublication . Simão, Laurentino; Alves, Cristina; Brito, Filomena; Marques, Bárbara; Ferreira, Cristina; Gaspar, Isabel; Dieudonne, V.; Cabral, P.; Meneses, I.; Duarte, Guida; Correia, HildebertoSmith-Magenis Syndrome (SMS) is a micro-deletion syndrome, and encompasses a picture of dysmorphology, mental defect, and fractious behavior. Evaluation of complex chromosome rearrangements (CCRs) and their potential phenotypic consequences is a common challenge in the genetics clinic and knowledge about the genotype/phenotype relationships are limited. We report the case of a 14-year-old boy who was referred by SMS, presenting developmental delay, fractious behavior, reduced sensitivity to pain, macrocranium and distinctive facial features. Following karyotyping, fluorescence in situ hybridization (FISH) using WCP probes for the chromosomes involved in CCR and 17p11.2 probe for SMS region was performed. Lately, chromosomal Comparative Genomic Hybridization (cCGH) and genomic microarray studies were also performed in order to identify genomic imbalances. The cytogenetic analysis revealed a karyotype: 46,XY,inv(3)(p23q27)t(3;10)(p13.2;p11.2),inv(14)(q13q32)dn.ish inv(3)t(3;10)(wcp10+), der(10)t(3;10)(wcp3+),inv(14)(wcp14+). Parental karyotypes were normal, although the father presented a marked cognitive delay. FISH analyses showed no deletion in 17p11.2 region and confirmed the cytogenetic results, namely the presence of CCR. Additionally, cCGH and genomic microarray studies did not reveal any gains/losses of genetic material in the breakpoints regions. Despite the clinical features of SMS, deletions or duplications in the SMS critical region were not detected in this patient. However, a small number of SMS present a mutation in the RAI1 gene instead of a 17p11.2 deletion, the former cause could not be excluded On the other hand, in CCRs de novo, an apparently balanced karyotype may be associated with an abnormal phenotype, including an increased risk of intellectual delay and congenital malformations. Further studies comprising, e.g., sequencing of the breakpoints, chromatin conformation analysis and refinement of the SMS critical region analysis might be useful to elucidate the phenotypic characteristics. However, the patient has been absent of routine clinical reevaluation; the etiology of the father’s cognitive delay could help shedding some light on the patient phenotypic features.
- Deletional alpha-thalassemia and hematological phenotype: predictive parameters of different deletionsPublication . Gaspar, Gisela; Ramalho, Rita de Mira; Seuanes, Filomena; Feliciano, Carla; Duarte, Guida; Copeto, Sandra; Costa, Alcina; Santos, João Xavier; Miranda, ArmandinaIntroduction: Thalassemias are characterized by a quantitative imbalance of the globin chains due to the reduction or suppression of the synthesis of one of the globin chains.The hematological tests usually used as indicative for the investigation of α-thalassemia are the blood count with MCV (Mean Cell Volume) < 80 fL and/or MCH (Mean Cell Hemoglobin) < 27 pg and normal Hb A2 (< 3.5%). Aim: This study aimed to correlate the different deletional α-thalassemia genetic alterations with the corresponding hematological phenotype, based on casuistry from 2015 to 2019. Methodology: Was evaluated retrospectively 496 cases suspected of deletional α-thalassemia from 2015 to 2019 and correlated them with the hematological data available. We searched for α-thalassemia deletions by Gap-PCR and Multiplex Gap-PCR. Haematological evaluation was carried out by the erythrogram, Hb isoelectric focusing and quantification of Hb A2 and Hb F (Ion exchange high performance liquid chromatography). The statistical analysis of the results was carried out through calculating the mean, standard deviation, median, and t-Student test, with a significance level of 0.05. Results and discussion: Most patients (n=190) had a normal genotype (αα/αα), followed by heterozygosity (-α3.7/αα) (n=148) and homozygosity (-α3.7/α3.7) (n=141) for the 3.7kb deletion. We also detected 5 cases of heterozygosity for the 4.2Kb deletion (-α4.2/αα), 4 of double heterozygosity (α3.7/α4.2), 7 heterozygosity α0 (--SEA /αα) and 1 of HbH (--SEA/-α3.7). The results showed that the MCV and the MCH are excellent hematological indices for screening and selection of patients for molecular testing (their value being the lower the greater the number of deleted genes). Our results are in line with those described in the literature and reinforce that the cut-off value of 25 pg (MCH) is sensitive enough to infer the presence of α0 -thalassemia deletion. The detection of the α0 deletion is very important in preventing the occurrence of Hb Bart's in the offspring of a carrier couple. The diagnosis of deletional α-thalassemia is realised by genetic testing, however hematological indices are relevant predictive markers of the number of deleted alpha genes and the phenotype /genotype correlation.
- Hemoglobinopatias nas células do cordão umbilicalPublication . Raimundo, Ana; Seuanes, Filomena; Duarte, Guida; Copeto, Sandra; Costa, SandraSegundo dados da Organização Mundial de Saúde, de janeiro de 2011, estima-se que cerca de 5% da população mundial seja portadora dos genes responsáveis pelo desenvolvimento de hemoglobinopatias e que, anualmente, nasçam cerca de 300.000 crianças com variantes graves destas patologias. O rastreio neonatal é uma forma eficaz de combate a este problema grave de saúde pública. Está bem estabelecido que a identificação neonatal da anemia das células falciformes pode diminuir substancialmente a mortalidade e morbilidade durante os primeiros 5 anos de vida. Esta informação fornece aos profissionais de saúde uma oportunidade de organizar uma supervisão médica imediata. O rastreio de hemoglobinopatias em amostras de sangue do cordão umbilical tem como principal objetivo identificar variantes de hemoglobinas em recém-nascidos. Por outro lado, este rastreio é obrigatório como controlo de qualidade de unidades de sangue de cordão umbilical (SCU) para criopreservação, pelo que todas as amostras de SCU devem ser sujeitas a este rastreio para eventual utilização terapêutica e/ou de transplante. O rastreio de hemoglobinopatias em amostras de sangue de recém-nascidos ou de SCU é realizado no nosso laboratório por duas metodologias alternativas - cromatografia líquida de alta pressão de troca iónica (HPLC) e focagem isoelétrica (FIE) em gel de agarose.
- A rare de novo unbalanced complex rearrangement involving chromosomes 12, 18 and 20 in a child with dysmorphic featuresPublication . Alves, Cristina; Marques, Bárbara; Brito, Filomena; Silva, Marisa; Rodrigues, Rosário; Duarte, Guida; Sousa, Ana Berta; Bicho, Anabela; Correia, HildebertoComplex chromosomal rearrangements (CCRs) are rare structural abnormalities that involve three or more breakpoints located on two or more chromosomes and are often associated with developmental delay, mental retardation and congenital anomalies. Here, we report the case of a rare de novo CCR in a girl who was 9 months old when first reported to us. At 15 months old, her clinical features included marked hypotonia, severe psychomotor delay, progressive postnatal microcephaly, strabismus, depressed nasal root, hands and feet malformations, heart defects, recurrent respiratory infections and bilateral hearing deficit still in study. Conventional cytogenetic analysis revealed an unbalanced complex rearrangement, involving chromosomes 12, 18 and 20, and an apparent loss of material of chromosome 18 resulting from an interstitial deletion. Further molecular cytogenetic studies were performed: whole chromosome painting probes for the involved chromosomes and chromosomal comparative genomic hybridization. These studies revealed that apparently no other chromosomes were involved and confirmed a del(18)(q21.1q22) of approximately 17 Mb on the derivative chromosome 18. The latter chromosome also had material from der(12) to der(20) in its constitution. As most CCRs involving chromosome 18q show rearrangements in the q21, some authors argue that this region might be a breakpoint “hotspot”. On the other hand, cases of single deletions on 18q are predominantly terminal. Interstitial deletions are much rarer, and to our knowledge, this is the first report of a CCR with a del(18)(q21.1q22). The phenotype of patients with deletions within this region, reported so far, seems very similar to the one of our patient, and this may contribute to a better understanding of the genotype–phenotype correlation in this type of structural abnormalities.
- A retrospective study of Down syndrome in prenatal diagnosis. Did chorionic villus sampling allow a better prevention?Publication . Simão, Laurentino; Silva, Marisa; Brito, Filomena; Alves, Cristina; Marques, Bárbara; Ferreira, Cristina; Ambrósio, Paula; Silva, Maria do Céu; Ventura, Catarina; Duarte, Guida; Caetano, Paula; Correia, Joaquim; Melo, AntonietaIntroduction Down syndrome (DS) is the most common single genetic cause of human moderate mental retardation, with an estimated prevalence of 9.2 cases per 10,000 live births. We aimed at analyzing changes in prenatal diagnosis (PND) over time, namely the referral reasons for chromosome analyses and the introduction of chorionic villus sampling (CVS), and its influence on the results obtained in DS cases. Methods We retrospectively evaluated the PND results from samples analyzed between 1987 and 2011 (25 years) in our cytogenetic laboratory taking into account the referral reasons, type of sample, karyotype and reporting time. Results 263 fetuses with a karyotype compatible with DS were identified in a total of 18,107 karyotypes (1.5%). The highest frequencies of DS were found among cases referred because of ultrasonography findigs (namely increased nuchal translucency) or positive first trimester screening and when one parent carries a chromosomal rearrangement. The frequency of recurrence was found to be 1/72. The increasing use of CVS led to an earlier response in terms of gestational age (mean at diagnosis- 13+4 weeks). In addition, an increased percentage of karyotypes with SD was detected (8.4% of CVS samples). On the other hand, implementation of molecular rapid aneuploidy detection in part of the samples allowed a better report time in DS cases, from 23 days in 1987 to 2 days in 2011. Discussion DS detection remains the most important reason for performing PND. The collecting of CVS has been rising over the last years, which has resulted in an increased number of trisomy 21 cases identified in a lower gestational age, allowing a better karyotype-phenotype correlation in earlier pregnancies. Moreover, the use of complementary molecular techniques for the detection of common aneuploidies reduced the mean reporting time and allowed an earlier decision of the couple concerning the future of gestation.