Quantitative studies on SMN1 gene and carrier testing of spinal muscular atrophy.
OBJECTIVE
To construct a method for detecting the copy number of survival of motor neuron 1 gene (SMN1) with single copy difference based on real-time fluorescence quantitative PCR, and to make practical use of the method for acquiring the data on SMN1 copy number in Chinese as well as for screening the carriers of spinal muscular atrophy (SMA) from healthy individuals and SMA families.


METHODS
Exon 7 and flanking area of SMN1 gene were amplified by real-time fluorescence quantitative PCR in 264 healthy individuals, in 1 standard sample having 2 SMN1 but having no SMN2, and in 88 parents of SMA patients. The samples for detecting were diluted to 30 ng/microL and the standard sample was diluted to 15 ng/microL, 30 ng/microL, 45 ng/microL, 60 ng/microL; the unknown samples and 4 standard samples with different concentrations were amplified at the same time, a standard curve could be drawn out according to the results of the 4 standard samples, then the copy number of samples could be calculated.


RESULTS
Of 88 parents' samples, 84 samples each had 1 copy of SMN1, and the rest 4 each had 2 copies of SMN1. Of 264 healthy individuals' samples, 5 samples each had only 1 copy of SMN1 (an indicator of definite gene carriers), 232 samples each had 2 copies of SMN1, 25 samples each had 3 copies of SMN1, and 2 samples each had 4 copies of SMN1. Of the samples of 32 members of SMA families, 2 samples each had only 1 copy of SMN1 indicating definite gene carriers, 25 samples each had 2 copies of SMN1, and 5 samples each had 3 copies of SMN1.


CONCLUSIONS
SMN1 copy number could be detected precisely by real-time fluorescence quantitative PCR; the screening of gene carriers could provide essential data for genetic counseling.
Chen
Wan-jin
WJ
Department of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, Fujian, P. R. China.
Wu
Zhi-ying
ZY
Wang
Ning
N
Lin
Min-ting
MT
Mu-rong
Shen-xing
SX
D005091:Exons; D005192:Family Health; D005260:Female; D005453:Fluorescence; D018628:Gene Dosage; D006801:Humans; D008297:Male; D009134:Muscular Atrophy, Spinal / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D055533:Survival of Motor Neuron 1 Protein / Q000235:genetics*
C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein