About 1 in 40 to 1 in 60 people are carriers of SMA. The SMN gene is present in two highly homologous and functional copies (TelSMN/SMN1 and CenSMN/SMN2). Patient 2 was compound heterozygous for two SMN1 mutations: whole-gene deletion and intragenic missense mutation, c.826T>C (p.Tyr276His). One copy of the father’s SMN1 genes was shown to carry the same intragenic mutation as the patient’s. The role of the survival motor neuron 1 (SMN1) gene is to produce SMN protein, which is highly expressed in the spinal cord and is known to be essential for motor neuron survival. The small amount of SMN protein produced by the SMN2 genes … Gene copy number and structure in SMA patients.
We also identified a homozygous deletion of SMN1 exon 8 in 37 of 42 patients (88.1%); the other 5 SMA patients (11.9%) had a single copy of SMN1 exon 8. These findings indicated that the father was an SMA carrier with [1 + 1 d] genotype. All individuals with spinal muscular atrophy have at least one “backup gene”, known as SMN2. People can have 1 or more copies of this backup gene.
Patient 2's father had two SMN1 copies with the same intragenic mutation in one copy ([1+1d] genotype, d intragenic mutation). The SMN gene exists in 2 highly homologous copies (SMN1 and SMN2) that have been mapped to chromosome region 5q13 [8]. The role of a backup gene. Multiple copies of the SMN2 gene are usually associated with less severe features of the condition that develop later in life. Approximately 94% of clinically typical SMA patients have a homozy-gous deletion of exon 7 of the telemetric copy of the gene (SMN1… About 1 in 6,000 to 1 in 10,000 children are born with SMA. gene conversion with the highly homologous, tightly linked SMN2 gene. SMN1 gene copy number analysis for spinal muscular atrophy (SMA) in a Turkish cohort by CODE-SEQ technology, an integrated solution for detection of SMN1 and SMN2 copy numbers and the "2+0" genotype. All SMA patients had a homozygous deletion of SMN1 exon 7. The telomeric copy of SMN gene (TelSMN/SMN1) seems to be the SMA-determining gene while the centromeric copy seems unaffected. determining gene [7]. SMN1 and SMN2 copy number assay (SMN gene dosage analysis) ... (43%) of 164 individuals with 2 SMN1 copies had one or zero SMN2 copies (P < 0.01; χ 2 test). SMN1 gene dosage analysis will confirm diagnosis for around 95% of patients with SMA, those with homozygous deletions of SMN1 [0+0]. A clinical overview of spinal muscular atrophy ... (SMN1) gene is to produce SMN protein, which is highly expressed in the spinal cord and is known to be essential for motor neuron survival 1,3. Ceylan AC(1), Erdem HB(2), Şahin İ(2), Agarwal M(3). For people with SMA, the SMN2 gene is the only source of SMN protein; however, it is unable to produce as much protein as the SMN1 gene.. The SMN2 gene has a similar structure to SMN1, but only a small amount (10%) of the SMN protein it produces is fully functional.This low level of SMN protein is not effective enough to sustain the survival of motor neurons in the CNS. The father in Family 2 was healthy and had two SMN1 copies. Typically, people have two copies of the SMN1 gene and one to two copies of the SMN2 gene in each cell.