Genetic analysis of 90 families affected with spinal muscular atrophy

Objective To carry out genetic testing and prenatal diagnosis for 90 families affected with spinal muscular atrophy (SMA), and discuss the necessity for carrier screening. Methods All families were subjected to multiplex ligation-dependent probe amplification (MLPA) analysis. Combined MLPA and allele-specific PCR (AS-PCR) was used for prenatal diagnosis of the pregnant women. Results Among the 90 couples, 84 (93%) had a negative family history, 85 (94%) had given birth to an affected child before. Eighty-five husbands and 88 wives carried heterozygous deletion of exon 7 of the SMN1 gene. Two wives had homozygous deletion of exon 7 of the SMN1 gene and were affected. Prenatal diagnosis showed that 19 fetuses were SMA patients, 48 fetuses were carriers, and 23 fetuses were normal. Of note, eighteen affected fetuses were conceived by couples without a family history, which accounted for 20% of all pregnancies and 95% of all affected fetuses. Conclusion To screen SMA carriers using MLPA and carry out prenatal diagnosis using combined MLPA and AS-PCR can ensure accurate diagnosis, which has a significant value for the prevention of SMA affected births. Key words: Spinal muscular atrophy; Multiplex ligation-dependent probe amplification; Allele-specific PCR; Genetic testing; Prenatal diagnosis