SNPs and real-time quantitative PCR method for constitutional allelic copy number determination, the VPREB1 marker case

作者：Frigerio Marcello^*; Passeri Elena; de Filippis Tiziana; Rusconi Daniela; Valaperta Rea; Carminati Mario; Donnangelo Anita; Costa Elena; Persani Luca; Finelli Palma; Corbetta Sabrina

来源：BMC Medical Genetics, 2011, 12: 61.

DOI：10.1186/1471-2350-12-61

• qRT-PCR allelic copy number
• 22q11.2 microdeletion
• DiGeorge Syndrome

Background: 22q11.2 microdeletion is responsible for the DiGeorge Syndrome, characterized by heart defects, psychiatric disorders, endocrine and immune alterations and a 1 in 4000 live birth prevalence. Real-time quantitative PCR (qPCR) approaches for allelic copy number determination have recently been investigated in 22q11.2 microdeletions detection. The qPCR method was performed for 22q11.2 microdeletions detection as a first-level screening approach in a genetically unknown series of patients with congenital heart defects. A technical issue related to the VPREB1 qPCR marker was pointed out.
Methods: A set of 100 unrelated Italian patients with congenital heart defects were tested for 22q11.2 microdeletions by a qPCR method using six different markers. Fluorescence In Situ Hybridization technique (FISH) was used for confirmation.
Results: qPCR identified six patients harbouring the 22q11.2 microdeletion, confirmed by FISH. The VPREB1 gene marker presented with a pattern consistent with hemideletion in one 3 Mb deleted patient, suggestive for a long distal deletion, and in additional five non-deleted patients. The long distal 22q11.2 deletion was not confirmed by Comparative Genomic Hybridization. Indeed, the VPREB1 gene marker generated false positive results in association with the rs1320 G/A SNP, a polymorphism localized within the VPREB1 marker reverse primer sequence. Patients heterozygous for rs1320 SNP, showed a qPCR profile consistent with the presence of a hemideletion.
Conclusions: Though the qPCR technique showed advantages as a screening approach in terms of cost and time, the VPREB1 marker case revealed that single nucleotide polymorphisms can interfere with qPCR data generating erroneous allelic copy number interpretations.

• 出版日期2011-5-5