Molecular analysis and prenatal prediction of spinal muscular atrophy in Chinese patients by the combination of restriction fragment length polymorphism analysis, denaturing high-performance liquid chromatography, and linkage analysis.
BACKGROUND
The difficulties and incurability of spinal muscular atrophy (SMA) highlight the importance of prenatal diagnosis in families with SMA. However, the system applied in prenatal screening is far from perfect.


OBJECTIVE
To optimize the molecular assays and establish a relatively perfect system for prenatal screening. Design, Setting, and Patients A total of 87 patients and 132 parents from 77 families with SMA were screened for SMN1 mutations. Prenatal prediction was performed for 11 fetuses from 10 families with SMA. All of the samples to be tested were from the Department of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China.


METHODS
All of the 87 patients and their parents were screened for SMN1 deletion by restriction fragment length polymorphism analysis and denaturing high-performance liquid chromatography (DHPLC). For those patients without the SMN1 deletion, the SMN1 copy numbers were detected by real-time fluorescence quantitative polymerase chain reaction and the subtle mutations of SMN were screened by direct sequencing. Prenatal prediction was performed by restriction fragment length polymorphism analysis, DHPLC, and linkage analysis for 11 fetuses. Furthermore, the SMN1 copy numbers and detected carriers of SMA were found by DHPLC and real-time fluorescence quantitative polymerase chain reaction in 14 parents and the fetuses without the SMN1 deletion. Results in aborted fetuses and born babies were reconfirmed by restriction fragment length polymorphism analysis and DHPLC. The born babies were followed up and physically examined twice a year.


RESULTS
The frequency of the SMN1 deletion we detected was 93.5% (72 of 77 patients). No subtle mutations were detected in the other 5 families. Four fetuses had the SMN1 deletion and were aborted. The other 7 fetuses, 4 carriers and 3 normal individuals, were born under suggestion by the physician. Fourteen parents were carriers. The reconfirmation of results in the aborted fetuses and born babies was completely consistent with prenatal prediction. The 7 born babies were followed up until recently and all were normal.


CONCLUSIONS
The molecular diagnosis system based on restriction fragment length polymorphism analysis, DHPLC, and linkage analysis is an efficient and accurate method that is well suited for routine use in clinical laboratories.
Chen
Wan-Jin
WJ
Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, 20 Chazhong Road, Fuzhou 350 005, China.
Wu
Zhi-Ying
ZY
Lin
Min-Ting
MT
Su
Jun-Feng
JF
Lin
Yu
Y
Murong
Shen-Xing
SX
Wang
Ning
N
D002648:Child; D002675:Child, Preschool; D002681:China; D002851:Chromatography, High Pressure Liquid; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D005091:Exons; D005260:Female; D005500:Follow-Up Studies; D008040:Genetic Linkage; D006801:Humans; D007223:Infant; D008297:Male; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis* / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D011247:Pregnancy; D011296:Prenatal Diagnosis; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein