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1.
Biochim Biophys Acta Mol Basis Dis ; 1863(3): 721-730, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28024938

RESUMO

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5FU). Genetic variations in DPD have emerged as predictive risk factors for severe fluoropyrimidine toxicity. Here, we report novel and rare genetic variants underlying DPD deficiency in 9 cancer patients presenting with severe fluoropyrimidine-associated toxicity. All patients possessed a strongly reduced DPD activity, ranging from 9 to 53% of controls. Analysis of the DPD gene (DPYD) showed the presence of 21 variable sites including 4 novel and 4 very rare aberrations: 3 missense mutations, 2 splice-site mutations, 1 intronic mutation, a deletion of 21 nucleotides and a genomic amplification of exons 9-12. Two novel/rare variants (c.2843T>C, c.321+1G>A) were present in multiple, unrelated patients. Functional analysis of recombinantly-expressed DPD mutants carrying the p.I948T and p.G284V mutation showed residual DPD activities of 30% and 0.5%, respectively. Analysis of a DPD homology model indicated that the p.I948T and p.G284V mutations may affect electron transfer and the binding of FAD, respectively. cDNA analysis showed that the c.321+1G>A mutation in DPYD leads to skipping of exon 4 immediately upstream of the mutated splice-donor site in the process of DPD pre-mRNA splicing. A lethal toxicity in two DPD patients suggests that fluoropyrimidines combined with other therapies such as radiotherapy might be particularly toxic for DPD deficient patients. Our study advocates a more comprehensive genotyping approach combined with phenotyping strategies for upfront screening for DPD deficiency to ensure the safe administration of fluoropyrimidines.


Assuntos
Antimetabólitos Antineoplásicos/efeitos adversos , Capecitabina/efeitos adversos , Di-Hidrouracila Desidrogenase (NADP)/genética , Fluoruracila/efeitos adversos , Mutação , Splicing de RNA , Idoso , Deficiência da Di-Hidropirimidina Desidrogenase/complicações , Deficiência da Di-Hidropirimidina Desidrogenase/genética , Feminino , Amplificação de Genes , Células HEK293 , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Moleculares , Mutação de Sentido Incorreto , Neoplasias/complicações , Neoplasias/tratamento farmacológico , Neoplasias/genética , Variantes Farmacogenômicos , Deleção de Sequência
2.
Am J Med Genet A ; 155A(5): 1066-72, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21465664

RESUMO

One of the recently recognized microdeletion syndromes is the 16p11.2 deletion syndrome (593 kb; ∼29.5 Mb to ∼30.1 Mb), associated with developmental delay, autism spectrum disorder, epilepsy, and obesity. Less frequently reported is a smaller 220 kb deletion, adjacent and distal to this 16p11.2 deletion, which has been referred to as the atypical 16p11.2 deletion (220 kb; ∼28.74 Mb to ∼28.95 Mb). We describe three patients with this deletion and update the manifestations in two sibs who have been described as possibly new entity in this Journal in 1997 [Bakker and Hennekam (1997); Am J Med Genet 70:312-314] and were recently found to have the "atypical 16p11.2 deletion" as well. Patients show a developmental delay, behavioral problems, and unusual facial morphology (prominent forehead, downslanted, and narrow palpebral fissures), and some are obese. We suggest that this "atypical" deletion may turn out to become a microdeletion syndrome that will be recognizable in the future, or at least to show a phenotype that is recognizable in retrospect. As it may no longer be so "atypical," we suggest renaming the entity "distal 16p11.2 deletion," to distinguish it from the common proximal 16p11.2 deletion.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 16 , Adolescente , Pré-Escolar , Feminino , Humanos , Masculino , Hibridização de Ácido Nucleico , Síndrome
3.
J Clin Endocrinol Metab ; 103(3): 917-925, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29342293

RESUMO

Context: Small for gestational age (SGA) can be the result of fetal growth restriction, which is associated with perinatal morbidity and mortality. Mechanisms that control prenatal growth are poorly understood. Objective: The aim of the current study was to gain more insight into prenatal growth failure and determine an effective diagnostic approach in SGA newborns. We hypothesized that one or more copy number variations (CNVs) and disturbed methylation and sequence variants may be present in genes associated with fetal growth. Design: A prospective cohort study of subjects with a low birth weight for gestational age. Setting: The study was conducted at an academic pediatric research institute. Patients: A total of 21 SGA newborns with a mean birth weight below the first centile and a control cohort of 24 appropriate-for-gestational-age newborns were studied. Interventions: Array comparative genomic hybridization, genome-wide methylation studies, and exome sequencing were performed. Main Outcome Measures: The numbers of CNVs, methylation disturbances, and sequence variants. Results: The genetic analyses demonstrated three CNVs, one systematically disturbed methylation pattern, and one sequence variant explaining SGA. Additional methylation disturbances and sequence variants were present in 20 patients. In 19 patients, multiple abnormalities were found. Conclusion: Our results confirm the influence of a large number of mechanisms explaining dysregulation of fetal growth. We concluded that CNVs, methylation disturbances, and sequence variants all contribute to prenatal growth failure. These genetic workups can be an effective diagnostic approach in SGA newborns.


Assuntos
Peso ao Nascer/genética , Retardo do Crescimento Fetal/genética , Recém-Nascido Pequeno para a Idade Gestacional , Hibridização Genômica Comparativa , Variações do Número de Cópias de DNA , Metilação de DNA , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Estudos Prospectivos , Sequenciamento do Exoma/métodos
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