SMN2 and NAIP gene dosages in Vietnamese patients with spinal muscular atrophy.
BACKGROUND
The SMN1 gene is now recognized as a spinal muscular atrophy (SMA)-causing gene, while SMN2 and NAIP have been characterized as a modifying factor of the clinical severity of SMA. Gene dosage of SMN2 is associated with clinical severity of SMA. But the relationship between gene dosage of NAIP and clinical severity of SMA remains to be clarified, although complete deletion of NAIP is frequent in type I patients.


METHODS
To evaluate the contribution of the SMN2 and NAIP gene dosages to SMA, quantitative real-time polymerase chain reaction was used to measure copy numbers of SMN2 and NAIP in 34 Vietnamese SMA patients lacking SMN1 (13 type I, 11 type II and 10 type III patients).


RESULTS
The SMN2 copy number in type I patients was significantly lower than that in type II-III patients, which was compatible with the previous reports. In contrast, 25 out of 34 patients had only zero or one copy of NAIP, while 50 out of 52 controls had two or more copies. For NAIP (+) genotype, six out of 13 type I patients, eight out of 11 type II patients and six out of 10 type III patients carried one NAIP copy.


CONCLUSIONS
The SMN2 copy number was related to the clinical severity of SMA among Vietnamese patients. The presence of one NAIP copy, that is, heterozygous NAIP deletion, was common in Vietnamese SMA, regardless of clinical phenotype.
Department of Pediatrics, Graduate School of Medicine, Kobe University, Japan.
Van Khanh
VK
Tran
Teguh Haryo
TH
Sasongko
Dang Diem
DD
Hong
Nguyen Thi
NT
Hoan
Vu Chi
VC
Dung
Myeong Jin
MJ
Lee
Gunadi
Yasuhiro
Y
Takeshima
Masafumi
M
Matsuo
Hisahide
H
Nishio
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D018628:Gene Dosage; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009134:Muscular Atrophy, Spinal / Q000453:epidemiology / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D051616:Neuronal Apoptosis-Inhibitory Protein / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D013997:Time Factors; D014744:Vietnam / Q000453:epidemiology
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D051616:Neuronal Apoptosis-Inhibitory Protein; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526477:SMN2 protein, human; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D004247:DNA