[Molecular Features of SMA-related Genes in Spinal Muscular Atrophy Patients of Han Nationality in Southwest China.].

OBJECTIVES

To investigate the molecular features of spinal muscular atrophy (SMA) related genes in SMA patients of Han nationality of southwest of China.

METHODS

We collected 62 unrelated patients of SMA and 50 unrelated healthy individuals in this study.The copy numbers of survival motor neuron gene (SMN) and uronal-apoptosis inhibitory protein gene (NAIP) were measured by using multiplex ligation-dependent probe amplification (MLPA).

RESULTS

Of 62 patients,the copy number of SMA1-4 were 30.65% (19/62),41.94%(26/62),16.13% (10/62),11.29% (7/62),respectively.The deletion of SMN1 exon 7 accounts for 98.38% (61/62).The deletion of SMN1 exon 8 accounts for 82.26% (51/62).Among SMA 1 patients,the homozygous deletion of NAIP exon 5 accounts for 68.42% (13/19) and heterzygous deletion accounts for 26.32% (5/19).Among SMA2-4patients,the homozygous deletion of NAIP exon 5 accounts for 13.95% (6/43) and heterzygous deletion accounts for 62.79% (27/43).Furthermore,68.42% (13/19) patients of SMA1have 1 copy and 2 copies of SMN2 gene,84.62% (22/26) patients of SMA 2 have more than 2 copies of SMN2 gene,90.00% (9/10) SMA3 and 85.71% (6/7) SMA4 have over 2 copies of SMN2 gene and even have 5 and 6 copy of SMN2 gene.

CONCLUSIONS

The deletion of SMN1 gene is the main cause of SMA,and the change of SMN2 and NAIP copy number can affect the severity of SMA.