RESUMEN

INTRODUCTION: This study was performed to assess the optimal resolution for prenatal testing by array comparative genomic hybridization (aCGH), aiming to balance between maximum diagnostic yield and minimal detection of variants of uncertain significance (VOUS). METHODS: This was a prospective study using data of 2,336 fetuses that underwent invasive prenatal diagnosis, and the samples were analyzed by aCGH. In total, six different aCGH platforms were studied; four different resolutions (0.18 Mb, 0.5 Mb, 1 Mb, and 2 Mb) and two platform designs (whole-genome [WG] and targeted). The results of these designs were compared based on their diagnostic yield and VOUS rate. The performance of the different designs was further analyzed according to indication for invasive testing. RESULTS: The diagnostic yield of copy number variants increased with increasing level of analysis. The detection rates of clinically significant chromosomal abnormalities were almost the same across our targeted array designs; 7.2% with 0.18 Mb backbone/0.05 Mb versus 7.1% with 0.5 Mb backbone/0.05 Mb (p >0.05). However, a significant difference in the rate of VOUS was observed; 9.4% with 0.18 Mb backbone/0.05 Mb versus 6% with 0.5 Mb backbone/0.05 Mb (p <0.001). After analyzing the results across different indications for testing, we found that the application of non-targeted platform designs and lower levels of resolution analysis (such as 1 Mb WG or 0.5 MbL/1 MbG WG) would offer similar diagnostic yield in most cases with major congenital anomalies, with lower VOUS rates. However, the sample size for many indication groups was too small to extract robust associations. CONCLUSION: It appears that the targeted array platform with 0.5 Mb backbone resolution and 0.05 Mb on targeted gene-rich regions is optimal for routine chromosomal microarray analysis use in prenatal diagnosis. It may be beneficial to individualize the minimum resolution in specific referral indications as the indications for invasive prenatal testing may be quite heterogeneous.

Asunto(s)

Aberraciones Cromosómicas , Diagnóstico Prenatal , Embarazo , Femenino , Humanos , Hibridación Genómica Comparativa/métodos , Estudios Prospectivos , Diagnóstico Prenatal/métodos , Análisis por Micromatrices , Variaciones en el Número de Copia de ADN

RESUMEN

Treacher Collins syndrome (TCS) is a type of mandibulofacial dysostosis with incomplete penetrance and high intra- and interfamilial clinical heterogeneity, and it is associated with mutations of treacle ribosome biogenesis factor 1 (TCOF1), and RNA polymerase I and III subunit (POLR1)C and POLR1D genes. In the present case report, a patient with TCS with auricle dysplasia and hearing loss accompanied with intellectual disability is described. Sequence analysis was performed on blood samples from the patient and his father via oligonucleotide-based target capture, followed by next-generation sequencing. Alignment and variant calls were generated using the Burrows-Wheeler Aligner and Genome Analysis Toolkit, followed by bioinformatics analysis of the detected variants. A novel heterozygous mutation, c.911C>T (p.Ser304Leu), was detected in the TCOF1 gene, which was inherited from the father. The father of the patient only suffered from hearing loss. The present report is the first to identify an association between phenotypic variability and TCOF1 gene mutations and thus contributes to our understanding of the association between the genotype and phenotype in patients with TCS and offers clinically relevant information for diagnosis of the syndrome.