Clinical application of single molecule real-time sequencing technology in gene detection for a child with 21-hydroxylase deficiency
Objective To determine the molecular etiology in a child with 21-hydroxylase deficiency using single mo-lecular real-time sequencing(SMRT),and explore its clinical application for gene detection.Methods SMRT tech-nology was applied to perform long-read sequencing on the candidate gene for congenital adrenal hyperplasia in the proband,and the results were compared to those obtained from multiplex ligation-dependent probe amplification(MLPA)and Sanger sequencing in the family.Results The SMRT results revealed three pathogenic variants in the proband's CYP21A2 gene,including two tandemly arranged gene copies on one chromosome(one CYP21A2 copy with c.955C＞T mutation and the other CYP21A2/CYP21A1P chimeric copy with a c.1069C＞T mutation),and a deletion of the CYP21A2 gene on the other chromosome.These variants were consistent with the results obtained by MLPA+Sanger sequencing in the family,and the arrangement of the CYP21A2/CYP21A1P chimeric gene was clarified.Conclusion SMRT technology can identify gene copy number variations,structure variations,and chimeric genes,providing more valuable information for genetic diagnosis and carrier screening of 21-hydroxylase deficiency.
Single molecular real-time sequencingLong-read sequencingCYP21A2 geneChimeric geneGene du-plication
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