Materials and methods for identifying carriers of genetic determinants of spinal muscular atrophy are disclosed. In particular, polymorphisms in linkage disequilibrium are associated as markers of spinal muscular atrophy alleles detectable by various techniques, including multiplex ligation-dependent probe analysis, sequence analysis, and RFLP detection. The materials and methods of the disclosure are particularly useful in identifying silent (2+0) carriers of spinal muscular atrophy in which two copies of the SMN1 gene are located on a single human chromosome 5 and no copies of the gene are located on the chromosome 5 homolog.