{{Rsnum
|rsid=398122990
|geno1=(A;A)
|geno2=(A;G)
|geno3=(G;G)
|Chromosome=X
|position=139541073
|Orientation=plus
|Gene=F9
|Gene_s=F9
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
}}[[rs398122990]] is a SNP in the coagulation factor IX [[F9]] gene, in an intron just upstream of the fourth exon. The F9 gene is on the X chromosome.

In 2009, researchers sequenced bones from the remains of the Nicholas II [http://en.wikipedia.org/wiki/House_of_Romanov Romanov] family, who were [http://en.wikipedia.org/wiki/Shooting_of_the_Romanov_family killed] in 1918. This family harbored a form of [[hemophilia]] known as the “[http://en.wikipedia.org/wiki/Haemophilia_in_European_royalty royal disease],” transmitted from Queen Victoria (1819–1901) to European royal families. The sequencing revealed the SNP responsible for their hemophilia, also known as hemophilia B or Christmas disease, to be [[rs398122990]]. To be specific, as an X-linked recessive disease, males (such as Prince Alexei) inheriting a [[rs398122990]](G) allele and females inheriting two copies would be hemophiliacs, while [[rs398122990]](A;G) females were unaffected carriers (as was Queen Victoria).{{PMID|19815722}}

On the suggestion of a Finnish researcher, in 2014 SNPedia submitted this SNP to dbSNP to have it assigned the rs-identifier you now see. It is currently unknown if this "royal disease" [[rs398122990]](G) SNP is extinct world-wide, i.e. no longer present even in a single unaffected carrier somewhere in the world. If through the use of [[Promethease]] or other tools this allele, [[rs398122990]](G), is identified in a human genome sequence derived from a living person, please contact us!{{ClinVar
|ALT=G
|CHROM=X
|CLNACC=RCV000077844.1
|CLNALLE=1
|CLNDBN=Hereditary factor IX deficiency disease
|CLNDSDB=GeneReviews:MedGen:OMIM:Orphanet:SNOMED_CT
|CLNDSDBID=NBK1495:C0008533:306900:98879:41788008
|CLNHGVS=NC_000023.10:g.138623232A>G
|CLNORIGIN=1
|CLNSIG=1
|Disease=Hereditary factor IX deficiency disease
|FwdALT=G
|FwdREF=A
|GENEINFO=F9:2158
|GENE_ID=2158
|GENE_NAME=F9
|REF=A
|RSPOS=138623232
|Reversed=0
|SAO=1
|SSR=0
|Tags=PM;PMC;OTHERKG;LSD;OM
|VC=SNV
|VP=0x050068000000000002110100
|WGT=0
|dbSNPBuildID=138
|rsid=398122990
}}