Segmental Duplications as a Complement Strategy to Short Tandem Repeats in the Prenatal Diagnosis of Down Syndrome

• Published in: Iranian journal of medical sciences Vol. 44; no. 3; pp. 214 - 219
• Main Authors: Miri, Mohammad Reza, Saberzadeh, Jamileh, Behzad Behbahani, Abbas, Tabei, Mohammad Bagher, Alipour, Mohsen, Fardaei, Majid
• Format: Journal Article
• Language: English
• Published: Iran Shiraz University of Medical Sciences 01-05-2019; Iranian Journal of Medical Sciences
• Subjects: Amniotic fluid; Anopheles; Chromosomes; Diagnosis; Down syndrome; Fluorescence; Health aspects; Medical research; Microsatellite repeats; Multiplex polymerase chain reaction; Original; Polymerase chain reaction; Pregnancy; Pregnant women; Segmental duplications; Iran; Segmental duplications; Down syndrome; Multiplex polymerase chain reaction; Microsatellite repeats
• ISSN: 0253-0716; 1735-3688
• DOI: 10.30476/ijms.2019.44976

Quantitative fluorescence-polymerase chain reaction (QF-PCR) is an inexpensive and accurate method for the prenatal diagnosis of aneuploidies that applies short tandem repeats (STRs) as a chromosome-specific marker. Despite its apparent advantages, QF-PCR is not applicable in all cases due to the presence of uninformative STRs. This study was carried out to investigate the efficiency of a method based on applying segmental duplications (SDs) in conjunction with STRs as an alternative to stand-alone STR-based QF-PCR for the diagnosis of Down syndrome.
Fifty amniotic fluid samples from pregnant women carrying Down syndrome fetuses, 9 amniotic fluid samples with 1 or without any informative STR marker (inconclusive), and 100 normal samples were selected from Shiraz, Iran, between October 2015 and December 2016. Analysis was done using an in-house STR-SD-based multiplex QF-PCR and the results were compared. Statistical analysis was performed using MedCalc, version 14.
All the normal, Down syndrome, and inconclusive samples were accurately identified by the STR-SD-based multiplex QF-PCR, yielding 100% sensitivity and 100% specificity. Karyotype analysis confirmed all the cases with normal or trisomic results.
The STR-SD-based multiplex QF-PCR correctly identified all the normal and trisomy 21 samples regardless of the absence of informative STR markers. The STR-SD-based multiplex QF-PCR is a feasible and particularly useful assay in populations with a high prevalence of homozygote STR markers.