Affiliations: Department of Pediatrics, Pediatric Health Research
Center, Tabriz University of Medical Sciences, Tabriz, Iran | Department of Genetics, Center of Excellence for
Biodiversity, Faculty of Natural Sciences, University of Thariz, Thariz,
Iran | Department of Pediatrics, Physical Medicine and
Rehabilitation Center, Tabriz University of Medical Sciences, Tabriz,
Iran
Note: [] Correspondence: Dr. Mohammad Barzegar, Pediatric Health Research
Center, Tabriz University of Medical Sciences, Tabriz, Iran. Tel.: +98 411
5262280; Fax: +98 411 5262280; E-mail: mm_barzegar@yahoo.com
Abstract: The childhood spinal muscular atrophy (SMA) is classified into three
groups based on the age of onset and clinical course. The aim of this study was
to define the correlation between genotype and phenotype in Iranian patients
with SMA. Molecular analysis was carried out on two candidate genes of survival
motor neuron one (SMN1), and neuronal apoptosis inhibitory protein (NAIP) in
189 patients with SMA (130 patients with SMA type I, 32 patients with type II
and 27 patients with type III) and the phenotypic features of SMA were compared
with the deletion pattern of these genes. Polymerase chain reaction along with
restriction fragment length polymorphism analysis were used to detect the
deletion of exons 7 and 8 of SMN1 gene, as well as multiplex polymerase chain
reaction for exon 5 of NAIP gene. Deletion in exon 7 was detected in 167
patients (88.4%); deletion in exon 8 was detected in 162 patients (85.7%) and
deletion in exon 5 of NIAP gene was detected in 95 patients (50.3%). Deletion
of exons 7 and/or 8 of SMN1 were detected in 90%, 84.4%, and 88.9% in patients
with types I, II and III SMA, respectively. The prevalence rates of exon 5
deletion in NAIP gene was 66.9%, 12.5%, and 14.8% in types I, II and III SMA
patients, respectively (P < 0.001). Combined homozygous deletion in both
SMN1 and NAIP genes was found in 65.4% SMA type I, 12.5% SMA type II and 14.8%
SMA type III (P < 0.001). There was a significant correlation between
combined deletion of both SMN1 and NAIP genes and clinical subtypes of SMA patients.
Keywords: Spinal muscular atrophy, survival motor neuron gene, neuronal apoptosis inhibitory protein gene, genotype and phenotype correlation
