SMA carrier testing – validation of hemizygous SMN exon 7 deletion test for the identification of proximal spinal muscular atrophy carriers and patients with a single allele deletion (original) (raw)

European Journal of Human Genetics volume 8, pages 79–86 (2000)Cite this article

Abstract

To facilitate the detection of carriers of a hemizygous survival motor neuron (SMN) exon 7 deletion we have modified the quantitative SMN exon 7 assay described by McAndrew et al (1997). The major changes include quantitative analysis of the amount of SMN exon 7-specific fluorescently-labelled PCR product on an automated sequencer, and the monitoring of the completeness of a DraI digestion necessary to distinguish the PCR products of exons 7 of SMN and its copy gene. In our method the amount of SMN exon 7 PCR product is compared with the amount of a co-amplified PCR product of the retinoblastoma (RB1) exon containing a DraI restriction site. By co-amplification using the same primers of plasmids included in the reaction as internal standards containing SMN exon 7 with a 36-nucleotide deletion and RB1 exon 13 with a 19-nucleotide deletion, respectively, the relative amplification efficacy can be monitored. The assay has been validated in 63 ascertained carriers and 28 ascertained non-carriers. The sensitivity of the test is approximately 97%, the specificity approaches 100%. In four out of six SMA patients without a homozygous deletion we detected a hemizygous deletion. The implications of the use of this assay for carrier testing and for confirmation of the clinical diagnosis of SMA are discussed.

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  1. Department of Medical Genetics, University of Groningen, The Netherlands
    Hans Scheffer, Jan Maarten Cobben, Rob GJ Mensink, Rein P Stulp, Gerrit van der Steege & Charles HCM Buys

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  1. Hans Scheffer
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  2. Jan Maarten Cobben
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  3. Rob GJ Mensink
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  4. Rein P Stulp
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  5. Gerrit van der Steege
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  6. Charles HCM Buys
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Correspondence toHans Scheffer.

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Scheffer, H., Cobben, J., Mensink, R. et al. SMA carrier testing – validation of hemizygous SMN exon 7 deletion test for the identification of proximal spinal muscular atrophy carriers and patients with a single allele deletion.Eur J Hum Genet 8, 79–86 (2000). https://doi.org/10.1038/sj.ejhg.5200404

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