Newborn screening is an important contribution to modern healthcare, as it allows the early detection of some serious genetic conditions and therefore a faster treatment. Each country has its own newborn screening program, depending on the evidence-based medical data and society's ability to provide the resources to implement newborn screening. Some developed countries have already included spinal muscular atrophy (SMA) and severe combined immunodeficiency (SCID) in their screening programme. In Slovenia, testing for these two diseases is only performed at the first suspicion and when the first symptoms are usually already present. By including SMA and SCID in the testing programme, these two diseases could be diagnosed before the appearance of serious symptoms and therefore prevent a more severe outcome or death of the patients. For screening purposes, we use samples of dried blood spots, from which DNA is isolated. The aim of this master thesis was to compare two genotyping assays for allele discrimination in qPCR amplified genetic markers in the SMN1 gene, the TREC and KREC circular fragment (TaqManTM SCID/SMA Plus Assay from Thermo Fisher scientific and EonisTM SCID-SMA kit from Perkin Elmer). Due to the lack of samples from SCID-positive patients, we only tested them with the Perkin Elmer SMA and SCID genetic marker genotyping assay and confirmed the absence of SCID markers. Both tests had the same sensitivity, while the Thermo Fisher Scientific test had a higher specificity. The t-test showed that the mean of Cq values for the SMN1 marker of the samples of people without SMA and SCID (negative controls) of the two tests compared were not statistically different. We found that the Perkin Elmer test is more accurate in determining the presence of genetic markers of SMA and SCID.
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