Novel rearrangements between different chromosomes with direct impact on the diagnosis of 5p- syndrome

Abstract Objectives Copy Number Variations (CNVs) in the human genome account for common populational variations but can also be responsible for genetic syndromes depending on the affected region. Although a deletion in 5p is responsible for a syndrome with highly recognizable phenotypical features, other chromosomal abnormalities might overlap phenotypes, especially considering that most studies in 5p use traditional cytogenetic techniques and not molecular techniques. Methods The authors have investigated 29 patients with clinical suspicion of 5p- syndrome using Chromosomal Microarray (CMA), and have gathered information on previous tests, clinical signs, symptoms, and development of the patients. Results The results showed 23 pure terminal deletions, one interstitial deletion, one deletion followed by a 3 Mb duplication in 5p, three cases of 5p deletion concomitant to duplications larger than 20 Mb in chromosomes 2, 9, and 18, and one 5p deletion with a chromosome Y deletion. CMA showed relevant CNVs not typically associated with 5p- that may have contributed to the final phenotype in these patients. Conclusions The authors have identified three novel rearrangements between chromosomes 5 and 2 (Patient 27), 5 and 18 (Patient 11), and 5 and Y (Patient 22), with breakpoints and overlapped phenotypes that were not previously described. The authors also highlight the need for further molecular investigation using CMA, in different chromosomes beyond chromosome 5 (since those cases did not show only the typical deletion expected for the 5p- syndrome) to explain discordant chromosomal features and overlapped phenotypes to unravel the cause of the syndrome in atypical cases. HIGHLIGHTS The authors The authors have described three novel rearrangements between chromosomes 5 and 2, 5 and 18, and 5 and Y with chromosomal breakpoints and overlapped phenotypes that were not previously described. One of the main atypical features for 5p- syndrome that the authors report was the presence of seizures that was found in the three patients with rearrangements between different chromosomes and in a patient with a deletion followed by duplication in 5p. The authors suggest physicians conduct further molecular investigation in the presence of atypical clinical features for patients with 5p- syndrome suspicion.

Genetic analysis of products of conception. Should we abandon classic karyotyping methodology? / Análise genética dos produtos de concepção. Devemos abandonar a metodologia de cariotipagem clássica?

ABSTRACT Objective: To compare the results obtained by the classic and molecular methodology in the analysis of products of conception, the advantages and disadvantages of each method. Methods: Retrospective non-randomized analysis of results obtained from product of conception samples submitted to genetic evaluation, from 2012 to 2017. The evaluations were performed using cytogenetics and/or chromosomal microarray analysis or arrays. Results: Forty samples were analyzed using classic cytogenetics, of which 10% showed no cell growth, 50% had normal results and 40% had abnormalities. Of the 41 cases sent for array analysis it was not possible to obtain results in 7.3%, 39.5% were normal and 60.5% had abnormalities. There was no statistical difference among the results (p=0.89). Most abnormal results were seen till 9 weeks' gestation. The later abnormal miscarriage was seen at 28 weeks' gestation, with karyotype 46,XX,del(15)(q26.2-qter). The results are corroborated by the international literature. Conclusion: Classic cytogenetics and array techniques showed comparable results on the type of alteration observed. Array analysis is preferable to cell culture in delayed abortions, while cytogenetics is more able to show polyploidies. Both have the same growth failure rates when product of conception tissue is not properly collected.

RESUMO Objetivo: Comparar os resultados obtidos pela metodologia clássica e molecular na análise de produtos de concepção, além das vantagens e desvantagens de cada método. Métodos: Análise retrospectiva não randomizada dos resultados obtidos a partir de amostras de produto de concepção submetidas à avaliação genética, de 2012 a 2017. As análises foram realizadas por citogenética clássica e/ou análise cromossômica de microarray ou arrays. Resultados: Quarenta amostras foram analisadas por citogenética, das quais 10% não apresentaram crescimento celular, 50% apresentaram resultados normais, e 40% apresentaram anormalidades. Dos 41 casos encaminhados para análise por array, não foi possível obter resultados em 7,3%, 39,5% eram normais, e 60,5% apresentavam alterações. Não houve diferença estatística entre os resultados (p=0,89). A maioria dos resultados anormais foi observada até a nona semana de gestação. Uma perda fetal mais tardia foi observada na 28ª semana de gestação, com cariótipo 46,XX,del(15)(q26.2-qter). Os números observados corroboraram a literatura mundial. Conclusão: As técnicas de citogenética clássica e análise por array mostraram resultados comparáveis no tipo de alteração observada. O array é preferível à cultura de células em abortos tardios, enquanto a citogenética é mais capaz de mostrar poliploidias. Ambos têm as mesmas taxas de falha de crescimento quando o tecido do produto de concepção não é coletado adequadamente.

Intellectual performance profi le of a sample of children and adolescents from Brazil with 22q11. 2 Deletion Syndrome (22q11. 2DS) based on the Wechsler Scale / Perfil de desempenho intelectual de uma amostra brasileira de crianças e adolescentes com Síndrome da Deleção 22q11. 2 (22q11. 2DS)com base na Escala Wechsler

The 22q11.2 Deletion Syndrome (22q11.2DS), the most common human chromosome microdeletion syndrome, is associated with a very heterogeneous neurocognitive phenotype. One of the main characteristics of the syndrome spectrum is the intellectual variability, which encompasses average performance and intellectual disability and discrepancies between Verbal Intelligence Quotient and Performance Verbal Intelligence Quotient, with greater impairment in nonverbal tasks. The present study aimed at investigating the intellectual performance aspects of a 21children and adolescents sample from Brazil who had been diagnosed with 22q11.2DS, based on the Wechsler Intelligence Scale for Children - 4th edition. The samples were reviewed considering the differences between indices. The results revealed an Full Scale Intelligence Quotient predominant in the borderline range (42 to 104) and a significant discrepancy between the indices of Verbal Comprehension and Perceptual Reasoning in 42% of the sample. With regard to the performance in the subtests alone, a better performance was found in Similarities, whereas block design, matrix reasoning, digit span and letter-number sequencing subtests were the most challenging. These findings indicate that a comprehensive assessment of intellectual performance aspects covering the different measures of the Wechsler Intelligence Scale may contribute to a broader understanding of the neurocognitive phenotype associated with 22q11.2DS.

A Síndrome da Deleção 22q11.2 (SD22q11.2), microdeleção cromossômica mais frequente em humanos, é associada a um fenótipo neurocognitivo muito heterogêneo. Uma das principais características do espectro da síndrome é a variabilidade intelectual, que abrange de desempenho médio a deficiência intelectual, bem como discrepâncias entre Quociente de Inteligência Verbal e de Quociente de Inteligência de Execução, com maior prejuízo nas tarefas não verbais. O presente estudo teve por objetivo investigar aspectos do desempenho intelectual de uma amostra brasileira de 21 crianças e adolescentes diagnosticados com SD22q11.2, com base nos indicadores da Wechsler Intelligence Scale for Children - 4th edition. As amostras foram analisadas considerando diferenças entre os índices. Os resultados revelaram predomínio de Quociente de Inteligência Total na faixa limítrofe, entre 42 e 104, assim como discrepância significativa entre os índices de compreensão verbal e organização perceptual em 42% da amostra. No que concerne ao desempenho nos subtestes de forma isolada, um melhor resultado foi verificado em semelhanças, ao passo que cubos, raciocínio matricial, dígitos e sequência de números e letras foram os mais desafiadores. Esses achados indicam que uma avaliação abrangente de aspectos do desempenho intelectual contemplando as diversas medidas da Escala Wechsler de Inteligência pode contribuir para uma compreensão mais ampla do fenótipo neurocognitivo associado à SD22q11.2.

Cytogenomic assessment of the diagnosis of 93 patients with developmental delay and multiple congenital abnormalities: The Brazilian experience

OBJECTIVE: The human genome contains several types of variations, such as copy number variations, that can generate specific clinical abnormalities. Different techniques are used to detect these changes, and obtaining an unequivocal diagnosis is important to understand the physiopathology of the diseases. The objective of this study was to assess the diagnostic capacity of multiplex ligation-dependent probe amplification and array techniques for etiologic diagnosis of syndromic patients. METHODS: We analyzed 93 patients with developmental delay and multiple congenital abnormalities using multiplex ligation-dependent probe amplifications and arrays. RESULTS: Multiplex ligation-dependent probe amplification using different kits revealed several changes in approximately 33.3% of patients. The use of arrays with different platforms showed an approximately 53.75% detection rate for at least one pathogenic change and a 46.25% detection rate for patients with benign changes. A concomitant assessment of the two techniques showed an approximately 97.8% rate of concordance, although the results were not the same in all cases. In contrast with the array results, the MLPA technique detected ∼70.6% of pathogenic changes. CONCLUSION: The obtained results corroborated data reported in the literature, but the overall detection rate was higher than the rates previously reported, due in part to the criteria used to select patients. Although arrays are the most efficient tool for diagnosis, they are not always suitable as a first-line diagnostic approach because of their high cost for large-scale use in developing countries. Thus, clinical and laboratory interactions with skilled technicians are required to target patients for the most effective and beneficial molecular diagnosis.

Investigation of Copy Number Variation in Children with Conotruncal Heart Defects / Investigação da Variação no Número de Cópias Gênicas em Crianças com Defeito Cardíaco Conotruncal

Background: Congenital heart defects (CHD) are the most prevalent group of structural abnormalities at birth and one of the main causes of infant morbidity and mortality. Studies have shown a contribution of the copy number variation in the genesis of cardiac malformations. Objectives: Investigate gene copy number variation (CNV) in children with conotruncal heart defect. Methods: Multiplex ligation-dependent probe amplification (MLPA) was performed in 39 patients with conotruncal heart defect. Clinical and laboratory assessments were conducted in all patients. The parents of the probands who presented abnormal findings were also investigated. Results: Gene copy number variation was detected in 7/39 patients: 22q11.2 deletion, 22q11.2 duplication, 15q11.2 duplication, 20p12.2 duplication, 19p deletion, 15q and 8p23.2 duplication with 10p12.31 duplication. The clinical characteristics were consistent with those reported in the literature associated with the encountered microdeletion/microduplication. None of these changes was inherited from the parents. Conclusions: Our results demonstrate that the technique of MLPA is useful in the investigation of microdeletions and microduplications in conotruncal congenital heart defects. Early diagnosis of the copy number variation in patients with congenital heart defect assists in the prevention of morbidity and decreased mortality in these patients. .

Fundamento: Os defeitos cardíacos congênitos são o grupo de anormalidades estruturais mais prevalentes ao nascimento e uma das principais causas de morbidade e mortalidade infantil. Estudos têm mostrado a contribuição da variação no número de cópias na gênese das malformações cardíacas. Objetivos: Investigar a variação no número de cópias gênicas em crianças com defeito cardíaco conotruncal. Métodos: Multiplex Ligation-dependent Probe Amplification (MLPA) foi realizado em 39 pacientes com defeito cardíaco conotruncal. Avaliação clínica e laboratorial foi realizada em todos os pacientes. Os pais dos probandos que apresentaram alterações também foram investigados. Resultados: Variação no número de cópias foi detectada em 7/39 pacientes: deleção 22q11.2, duplicação 22q11.2, duplicação 15q11.2, duplicação 20p12.2, deleção 19p, duplicação 15q e 8p23.2 com duplicação 10p12.31. As características clínicas foram compatíveis com o relatado na literatura associadas com microdeleção/microduplicação encontrada. Nenhuma dessas alterações foi herdada dos pais. Conclusões: Nossos resultados demonstram que a técnica de MLPA é útil na investigação de microdeleções e microduplicações em defeitos cardíacos congênitos conotruncais. O diagnóstico precoce das variações no número de cópias em pacientes com defeito cardíaco congênito auxilia na prevenção de morbidade e diminuição da mortalidade nesses pacientes. .

Deleção 22q11.2 em pacientes com defeito cardíaco conotruncal e fenótipo da síndrome da deleção 22q11.2 / Deleción 22q11.2 en pacientes con defecto cardiaco conotruncal y fenotipo del síndrome de la deleción 22q11.2 / 22q11.2 deletion in patients with conotruncal heart defect and del22q syndrome phenotype

FUNDAMENTO: A síndrome da deleção 22q11.2 é a mais freqüente síndrome de microdeleção humana. O fenótipo é altamente variável e caracterizado por defeito cardíaco conotruncal, dismorfias faciais, insuficiência velofaríngea, dificuldade de aprendizagem e retardo mental. OBJETIVO: O objetivo deste trabalho foi investigar a freqüência da deleção 22q11.2 em uma amostra brasileira de indivíduos portadores de cardiopatia conontrucal isolada e do fenótipo da síndrome da deleção 22q11.2. MÉTODOS: Vinte e nove pacientes foram estudados por meio de citogenética clássica, por hibridação in situ fluorescente (FISH) e por técnicas moleculares. RESULTADOS: A análise citogenética por meio de bandamento G revelou cariótipo normal em todos os pacientes, com exceção de um que apresentou cariótipo 47,XX,+idic(22)(q11.2). Com o uso de técnicas moleculares, a deleção foi observada em 25 por cento dos pacientes, todos portadores do fenótipo da síndrome da deleção 22q11.2. Em nenhum dos casos, a deleção foi herdada dos pais. A freqüência da deleção 22q11.2 foi maior no grupo de pacientes portadores do espectro clínico da síndrome da deleção 22q11.2 do que no grupo de pacientes com cardiopatia conotruncal isolada. CONCLUSÃO: A investigação da presença da deleção e sua correlação com os dados clínicos dos pacientes podem auxiliar os pacientes e suas famílias a terem um melhor aconselhamento genético e um seguimento clínico mais adequado.

BACKGROUND: The 22q11.2 deletion syndrome is the most frequent human microdeletion syndrome. The phenotype is highly variable, being characterized by conotruncal heart defect, facial dysmorphisms, velopharyngeal insufficiency, learning difficulties and mental retardation. OBJECTIVE: The objective of this study was to investigate the frequency of deletion 22q11.2 in a Brazilian sample of individuals with isolated conotruncal heart defect and 22q11.2 deletion syndrome phenotype. METHODS: Twenty-nine patients were studied by classical cytogenetics, by fluorescence in situ hybridization (FISH), and by molecular techniques. RESULTS: Cytogenetic analysis by G-banding revealed a normal karyotype in all patients except one who presented a 47,XX,+idic(22)(q11.2) karyotype. Using molecular techniques, a deletion was observed in 25 percent of the patients, all exhibiting a 22q11.2 deletion syndrome phenotype. In none of the cases the deletion was inherited from the parents. The frequency of 22q11.2 deletion was higher in patients with the clinical spectrum of the 22q11.2 deletion syndrome than in patients with isolated conotruncal heart defect. CONCLUSION: Investigating the presence of the deletion and its correlation with the patients' clinical data can help the patients and their families to have a better genetic counseling and more adequate clinical follow-up.

FUNDAMENTO: El síndrome de la deleción 22q11.2 es el más frecuente síndrome de microdeleción humana. El fenotipo, altamente variable, se caracteriza por defecto cardiaco conotruncal, dismorfias faciales, insuficiencia velofaríngea, dificultad de aprendizaje y retardo mental. OBJETIVO: El objetivo de este trabajo fue investigar la frecuencia tanto de la deleción 22q11.2 en una muestra brasileña de individuos portadores de cardiopatía conotrucal aislada, como del fenotipo del síndrome de la delación 22q11.2. MÉTODOS: Se estudiaron a 29 pacientes por medio de citogenética clásica, por hibridación in situ fluorescente (FISH) y también por técnicas moleculares. RESULTADOS: El análisis citogenético por medio de bandeo G reveló cariotipo normal en todos los pacientes, con excepción de uno, que presentó cariotipo 47,XX,+idic(22)(q11.2). Con la utilización de técnicas moleculares, se observó la deleción en el 25 por ciento de los pacientes, todos portadores del fenotipo del síndrome de la deleción 22q11.2. En ningún de los casos, la deleción se heredó de los padres. La frecuencia de la deleción 22q11.2 en el grupo de pacientes portadores del espectro clínico de este síndrome resultó mayor que en el grupo de pacientes con cardiopatía conotruncal aislada. CONCLUSIÓN: La investigación de la presencia de deleción y su correlación con los datos clínicos de los pacientes pueden auxiliar los pacientes y sus familias a tener un mejor aconsejamiento genético, así como un seguimiento clínico más adecuado.