{{Rsnum
|rsid=121912617
|Chromosome=12
|Orientation=minus
|geno1=(C;C)
|geno2=(C;G)
|geno3=(G;G)
|Gene=BHLHE41
|position=26122364
|Gene_s=BHLHE41
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
}}[[rs121912617]], also known as Pro384Arg or P384R, is a SNP in the basic helix-loop-helix family, member e41 [[BHLHE41]] gene. Note that some publications and OMIM refer to this as Pro385 (rather than 384).

replicated {{PMID|25083013}}

Individuals heterozygous for [[rs121912617]] are known as Familial Natural Short Sleepers (FNSS), and they sleep 6–6.5 hours per night (∼2 hours less than controls) on average, without reporting any sense of sleep deprivation.{{PMID|19679812}} This is classified as a [[sleep disorder]], although it does not appear to have any known negative medical consequence.



{{omim
|id=606200
|rsnum=121912617
|variant=0001
}}{{ClinVar
|rsid=121912617
|Reversed=1
|FwdREF=C
|FwdALT=G
|REF=G
|ALT=C
|RSPOS=26275297
|CHROM=12
|dbSNPBuildID=133
|SSR=0
|SAO=1
|VP=0x050060000000000002110100
|GENEINFO=BHLHE41:79365
|GENE_NAME=BHLHE41
|GENE_ID=79365
|WGT=0
|VC=SNV
|CLNALLE=1
|CLNHGVS=NC_000012.11:g.26275297G>C
|CLNSRC=OMIM Allelic Variant
|CLNORIGIN=1
|CLNSRCID=606200.0001
|CLNSIG=5
|CLNCUI=C0751509
|CLNDBN=Short-sleeper
|Disease=Short-sleeper
|CLNACC=RCV000004788.1
|Tags=RV;PM;OTHERKG;LSD;OM
|CLNDSDB=MedGen:OMIM:SNOMED_CT
|CLNDSDBID=C0751509:612975:192007009
}}