A comprehensive overview of SMN and NAIP copy numbers in Iranian SMA patients

• Published in: Scientific reports 2023-02, Vol.13 (1), p.3202-3202, Article 3202
• Main Authors: Savad, Shahram, Ashrafi, Mahmoud Reza, Samadaian, Niusha, Heidari, Morteza, Modarressi, Mohammad-Hossein, Zamani, Gholamreza, Amidi, Saloomeh, Younesi, Sarang, Amin, Mohammad Mahdi Taheri, Saadati, Pourandokht, Ronagh, Alireza, Ardakani, Hossein Shojaaldini, Eslami, Solat, Ghafouri-Fard, Soudeh
• Format: Article
• Language: English
• Subjects: 631/208; 631/337; 631/80; DNA Copy Number Variations; Exons; Gene deletion; Genetic counseling; Genetic screening; Genomes; Genotype & phenotype; Genotypes; Homozygote; Humanities and Social Sciences; Humans; Iran; Laboratories; Minority & ethnic groups; multidisciplinary; Muscular Atrophy, Spinal - genetics; Neuromuscular diseases; Neuronal Apoptosis-Inhibitory Protein - genetics; Science; Science (multidisciplinary); Sequence Deletion; SMN protein; Spinal muscular atrophy; Survival of Motor Neuron 1 Protein - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-30449-7

Spinal muscular atrophy (SMA) is among the most common autosomal recessive disorders with different incidence rates in different ethnic groups. In the current study, we have determined SMN1 , SMN2 and NAIP copy numbers in an Iranian population using MLPA assay. Cases were recruited from Genome-Nilou Laboratory, Tehran, Iran and Pars-Genome Laboratory, Karaj, Iran during 2012–2022. All enrolled cases had a homozygous deletion of exon 7 of SMN1 . Moreover, except for 11 cases, all other cases had a homozygous deletion of exon 8 of SMN1 . Out of 186 patients, 177 (95.16%) patients showed the same copy numbers of exons 7 and 8 of SMN2 gene. In addition, 53 patients (28.49%) showed 2 copies, 71 (38.17%) showed 3 copies and 53 patients (28.49%) showed 4 copies of SMN2 gene exons 7 and 8. The remaining 9 patients showed different copy numbers of exons 7 and 8 of SMN2 gene. The proportions of SMA patients with different numbers of normal NAIP were 0 copy in 73 patients (39.24%), 1 copy in 59 patients (31.72%), 2 copies in 53 patients (28.49%) and 4 copies in one patient (0.5%). These values are different from values reported in other populations. Integration of the data of the SMN1 / 2 and NAIP genes showed 17 genotypes. Patients with genotype 0-0-3-3-1 (0 copies of SMN1 (E7,8), 3 copies of SMN2 (E7,8) and 1 copy of NAIP (E5)) were the most common genotype in this study. Patients with 0-0-2-2-0 genotype were more likely to have type I SMA. The results of the current study have practical significance, particularly in the genetic counseling of at-risk families.