rs184039278

A SNP in the CRY1 gene on chromosome 12. Its most notable genotype is G;G: Delayed sleep phase possible; tendency to be a night owl?

Gene
CRY1
Location
Chr 12106,992,962 (GRCh38)
Highest magnitude
3.3Important
Tested on
Not on consumer chips

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. G;GMost notableBadDelayed sleep phase possible; tendency to be a night owl?Important · 3.3
  2. G;TBadDelayed sleep phase possible; tendency to be a night owl?Important · 3.3
  3. T;TGoodcommon/normalTypical · 0.0

On SNPedia: (G;G), (G;T), (T;T). 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 180 words

rs184039278, also known as c.1657+3A>C, is a variant in the CRY1 gene on chromosome 12. Around 1 in 75 Caucasians carry the minor allele of this SNP. Acting in a dominant manner, the rs184039278(G) allele (as oriented in dbSNP) was observed in individuals who had delayed sleep phase disorder (DSPD), characterized by staying up later (i.e. being night owls). Although this initial report is based on less than 10 families, all of whom are Turkish, the correlation observed for the ~70 individuals studied (8 homozygous carriers, 31 heterozygous carriers, 31 non-carriers) was close to 100%, suggesting this variant is of high penetrance. Note that since the reported number of "night owls" is larger than 1 in 75, even if this variant turns out to be a cause of staying up late at night (and fragmented sleep patterns and related sleep disorder), there are going to be many night owls who do not carry the variant allele of this SNP and who have other causes (genetic or otherwise) for their sleep habits.

G;G

see discussion at rs184039278

G;T

see discussion at rs184039278

Source and license

Adapted from rs184039278 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 Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice.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.