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Background: 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. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Background: Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of hepatic disorders that can progress rapidly, leading to cirrhosis and death due to liver failure. Mutations and variations in three genes, including ATP8B1, ABCB11, and ABCB4, have been reported to be the main genetic cause of three subtypes of this disorder including PFIC1, PFIC2, and PFIC3, respectively. Objectives: Therefore, the aim of this study was to investigate more common mutations and variations associated with PFIC considering clinical and Para-clinical features of the disease. Methods: Thirty-five unrelated patients with PFIC from the south of Iran were selected randomly among all PFIC patients referring to Namazi hospital, affiliated to Shiraz University of Medical Sciences. Genomic DNA was extracted from the peripheral blood lymphocytes. Sequences related to these variations were then amplified by PCR in the 35 cholestasis patients and analyzed by Sanger® sequencing. Results: The results showed that there was no variation in interest exon of ABCB4. Moreover, in ATP8B1, there was no prevalent mutation and only an unknown significant variation (c.*11 01+366G> A) was found. However, in the ABCB11 gene, different variations were found including c.1434 + 174G > A, c.1434 + 70C > T, c.1331T > C (p.Val444Ala, a common variant proposed to be associated with cholestasis), c.1309-93G > A, c.1309-165C > T. Also, 11 and 13 cases showed heterozygote and homozygote, respectively, for V444A variation of the ABCB11 gene. Conclusions: The allele frequency of V444A in this study was 52.8%. This variation has been previously implicated with higher frequencies in ICP and DIC than normal subjects, suggesting that this variation may become disease-relevant in certain conditions. [ABSTRACT FROM AUTHOR]