Carrier frequency of SMA by quantitative analysis of the SMN1 deletion in the Iranian population

Background and purpose: Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder. Carrier frequency studies of SMA have been reported for various populations. Although no large-scale population-based studies of SMA have been performed in Iran, previous estimates have indicated that the incidence of autosomal recessive disorder partly because of the high prevalence of consanguineous marriage is much higher in the Iranian population than in other populations. Methods: In this study, we used a reliable and highly sensitive quantitative real-time PCR assay with SYBR green I dye to detect the copy number of the SMN1 gene to determine the carrier frequency of SMA in 200 healthy unrelated, non-consanguineous couples from different part of Iran. Results: To validate the method in our samples, we determined the relative quantification (RQ) of patients with homozygous deletion (0.00) and hemyzygous carriers (0.29-0.55). The RQ in 10 of 200 normal individuals were within the carrier range of 0.31-0.57, estimating a carrier frequency of 5% in the Iranian population. Conclusions: Our data show that the SMA carrier frequency in Iran is higher than in the European population and that further programs of population carrier detection and prenatal testing should be implemented.