ABSTRACT
El amplio espectro de aberraciones cromosómicas observable en los trastornos del neurodesarrollo no siempre puede ser caracterizado por análisis cromosómico. El objetivo del trabajo fue determinar la etiología genética de estos trastornos en pacientes con afecciones neurológicas congénitas y sospecha clínica de un síndrome genético, aplicando un algoritmo de estudio clínico-molecular. En 71 de 111 niños analizados, se hallaron aberraciones submicroscópicas asociadas a síndromes de microdeleción-microduplicación: DiGeorge (22 casos), Prader-Willi (26 casos), Angelman (2 casos), Williams-Beuren (17 casos), Smith-Magenis (1 caso), Miller-Dieker (1 caso) y síndrome cri du chat (1 caso). Adicionalmente, se detectó una inserción desbalanceada de novo de la región 17p12p11.2, en el punto 5p13.1, en un niño de tres años. La utilización del método clínico unido a técnicas moleculares, como hibridación fluorescente in situ, ha permitido, en la mayoría de los casos, el diagnóstico certero de pacientes y/o familias con trastornos del neurodesarrollo.
The wide range of chromosome aberrations seen in neurodevelopmental disorders may not always be characterized by means of a chromosome analysis. The objective of this study was to determine the genetic etiology of these disorders in patients with congenital neurological conditions and clinical suspicion of a genetic disorder using a clinical and molecular testing algorithm. Among 111 studied children, 71 showed submicroscopic chromosome aberrations associated with microdeletion/microduplication syndromes: DiGeorge (22 cases), Prader-Willi (26 cases), Angelman (2 cases), Williams-Beuren (17 cases), Smith-Magenis (1 case), Miller-Dieker (1 case), and cri du chat syndrome (1 case). Additionally, a de novo trisomy 17p12p11.2 due to an unbalanced insertion into 5p13.1 was identified in a 3-year-old child. In most cases, the use of a clinical method together with molecular techniques, such as fluorescence in situ hybridization, has allowed to make an accurate diagnosis in patients and/or families with neurodevelopmental disorders.
Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Neurodevelopmental Disorders/diagnosis , Genetic Diseases, Inborn/diagnosis , Syndrome , Algorithms , Developmental Disabilities , Retrospective Studies , In Situ Hybridization, Fluorescence , Critical Pathways , Neurodevelopmental Disorders/etiology , Genetic CounselingABSTRACT
OBJECTIVE: To explore the clinical value of non-invasive prenatal testing(NIPT)for screening fetal chromosomal copy number variations(CNVs) and microdeletion/microduplication syndromes(MDs).METHODS: Retrospective analysis was made in the 10 005 women who received NIPT during the first trimester(15-20+ 6 weeks)from January,2012 to July,2017,at First People's Hospital of Yunnan Province,Department of Genetic Diagnosis Center.Among them 32 pregnant women were indicated fetal CNVs,25 of 32 pregnant women selected interventional prenatal diagnosis.Statistical analysis was made on the amniotic fluid/cord blood chromosome G band karyotype and high-throughput sequencing(NGS)genome copy number analysis was made,and relevant CNVs were searched and analyzed in the corresponding database;the consistency of CNVs found in NIPT with interventional prenatal diagnosis was statistically analyzed.RESULTS: During the second trimester(15-20+ 6 weeks),in the 10 005 pregnant women who received NIPT testing 32 cases were shown to have high risks of fetal CNVs,and the screening positive rate was 0.32%(32/10 005).In 25 high risk pregnant women who accepted invasive prenatal diagnosis via informed choice,14 women wereconfirmed as fetal CNVs,the positive predictive value(PPV)of NIPT being 56%(14/25),including 9 cases of microdeletion and 5 cases of microduplication.The sizes were between 587.75 kb and 36.05 Mb.The size and the start and end positions of CNVs found by NIPT were similar to those of fetal DNA samples detected by NGS.Among 14 cases of fetal CNVs,11 cases were identified as MDs,3 cases as unknown clinical significance.In 11 cases of MDs,8 cases were observed fetal chromosome structure abnormalities by karyotype analysis,10 cases were confirmed as de novo abbreviations,and 2 cases as originated from paternal same MD.After genetic counseling,10 pregnant women in 11 cases of MDs chose informed terminations,and one case chose continuing pregnancy.CONCLUSION: As a high-precision screening method,NIPT is expected to be an effective mean to screen for fetal CNVs,which can be used to detect highrisk chromosome microdeletion and microduplication CNVs of larger segments.High risk cases of fetal CNVs found by NIPT require invasive prenatal diagnosis for validation.