rs4916

A SNP in the SMN2 gene on chromosome 5. Its most notable genotype is C;C: common in complete genomics

Gene
SMN2
Location
Chr 570,076,526 (GRCh38)
Highest magnitude
0.0Typical
Tested on
Not on consumer chips

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. C;CMost notableGoodcommon in complete genomicsTypical · 0.0

On SNPedia: (C;C). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Conditions, medicines and genes

Notes

From SNPedia

Show notes, about 170 words

This SNP is discussed in the discussion of spinal muscular atrophy (SMA); it is a SNP theoretically found in exon 7 of the SMN1 gene. In a world with perfect analytic tests, there would be 3 possible genotypes most likely to arise from this SNP: (-;-), (-;C), and (C;C), indicated spinal muscular atrophy patients, carriers for SMA, and non-carriers, respectively. However, due to the presence of identical flanking sequences to either side of this location in the genome for the near identical gene SMN2, an imperfect test can yield a (T;T) genotype for this SNP, which is really just a read of the SMN2 gene sequence at this location. Test that determine the ratio of what could be called rs4916(C) to rs4916(T) "alleles" may be possible to determine dosage ratio between SMN1 and SMN2. Unaffected individuals should have a 1:1 ratio of (C):(T) "alleles", SMA carriers should have a 1:2 ratio of (C):(T) "alleles", and 95% of SMA patients should show have only (T) "alleles" (without any (C) signal).

Source and license

Adapted from rs4916 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.

SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.