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CMAHP cytidine monophospho-N-acetylneuraminic acid hydroxylase, pseudogene [ Homo sapiens (human) ]

Gene ID: 8418, updated on 8-Dec-2022


Official Symbol
CMAHPprovided by HGNC
Official Full Name
cytidine monophospho-N-acetylneuraminic acid hydroxylase, pseudogeneprovided by HGNC
Primary source
See related
Ensembl:ENSG00000168405 MIM:603209; AllianceGenome:HGNC:2098
Gene type
RefSeq status
Homo sapiens
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo
Also known as
Sialic acids are terminal components of the carbohydrate chains of glycoconjugates involved in ligand-receptor, cell-cell, and cell-pathogen interactions. The two most common forms of sialic acid found in mammalian cells are N-acetylneuraminic acid (Neu5Ac) and its hydroxylated derivative, N-glycolylneuraminic acid (Neu5Gc). Studies of sialic acid distribution show that Neu5Gc is not detectable in normal human tissues although it was an abundant sialic acid in other mammals. Neu5Gc is, in actuality, immunogenic in humans. The absense of Neu5Gc in humans is due to a deletion within the human gene CMAH encoding cytidine monophosphate-N-acetylneuraminic acid hydroxylase, an enzyme responsible for Neu5Gc biosynthesis. Sequences encoding the mouse, pig, and chimpanzee hydroxylase enzymes were obtained by cDNA cloning and found to be highly homologous. However, the homologous human cDNA differs from these cDNAs by a 92-bp deletion in the 5' region. This deletion, corresponding to exon 6 of the mouse hydroxylase gene, causes a frameshift mutation and premature termination of the polypeptide chain in human. It seems unlikely that the truncated human hydroxylase mRNA encodes for an active enzyme explaining why Neu5Gc is undetectable in normal human tissues. Human genomic DNA also shows evidence of this deletion which does not occur in the genomes of African great apes. Nonetheless, the CMAH gene maps to 6p21.32 in humans and great apes indicating that mutation of the CMAH gene occurred following human divergence from chimpanzees and bonobos. [provided by RefSeq, Jul 2008]
Ubiquitous expression in skin (RPKM 10.5), lung (RPKM 9.3) and 23 other tissues See more
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Genomic context

See CMAHP in Genome Data Viewer
Exon count:
Annotation release Status Assembly Chr Location
110 current GRCh38.p14 (GCF_000001405.40) 6 NC_000006.12 (25081067..25138392, complement)
110 current T2T-CHM13v2.0 (GCF_009914755.1) 6 NC_060930.1 (24946777..25004128, complement)
105.20220307 previous assembly GRCh37.p13 (GCF_000001405.25) 6 NC_000006.11 (25081295..25138620, complement)

Chromosome 6 - NC_000006.12Genomic Context describing neighboring genes Neighboring gene RHO family interacting cell polarization regulator 2 Neighboring gene uncharacterized LOC102724765 Neighboring gene RNA, 7SL, cytoplasmic 334, pseudogene Neighboring gene argininosuccinate synthetase 1 pseudogene 1 Neighboring gene uncharacterized LOC124901282 Neighboring gene calcium activated nucleotidase 1 pseudogene Neighboring gene nucleoporin 50 pseudogene 2

Genomic regions, transcripts, and products


  • Project title: HPA RNA-seq normal tissues
  • Description: RNA-seq was performed of tissue samples from 95 human individuals representing 27 different tissues in order to determine tissue-specificity of all protein-coding genes
  • BioProject: PRJEB4337
  • Publication: PMID 24309898
  • Analysis date: Wed Apr 4 07:08:55 2018


GeneRIFs: Gene References Into Functions

What's a GeneRIF?


Products Interactant Other Gene Complex Source Pubs Description

General gene information


Other Names

  • CMP-N-acetylneuraminic acid hydroxylase
  • CMP-Neu5Ac hydroxylase
  • CMP-NeuAc hydroxylase
  • CMP-sialic acid hydroxylase
  • cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMP-N-acetylneuraminate monooxygenase)(pseudogene)

Gene Ontology Provided by GOA

Function Evidence Code Pubs
enables CMP-N-acetylneuraminate monooxygenase activity IBA
Inferred from Biological aspect of Ancestor
more info
NOT enables CMP-N-acetylneuraminate monooxygenase activity NAS
Non-traceable Author Statement
more info
Process Evidence Code Pubs
involved_in CMP-N-acetylneuraminate metabolic process IBA
Inferred from Biological aspect of Ancestor
more info
involved_in regulation of Wnt signaling pathway IMP
Inferred from Mutant Phenotype
more info
Component Evidence Code Pubs
located_in cytoplasm IDA
Inferred from Direct Assay
more info
located_in cytoskeleton IDA
Inferred from Direct Assay
more info
located_in membrane IDA
Inferred from Direct Assay
more info
located_in nucleus IDA
Inferred from Direct Assay
more info

NCBI Reference Sequences (RefSeq)

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RefSeqs maintained independently of Annotated Genomes

These reference sequences exist independently of genome builds. Explain

These reference sequences are curated independently of the genome annotation cycle, so their versions may not match the RefSeq versions in the current genome build. Identify version mismatches by comparing the version of the RefSeq in this section to the one reported in Genomic regions, transcripts, and products above.


  1. NR_002174.2 RNA Sequence

    Status: VALIDATED

    Transcript Variant: This variant (1) represents the longer transcript.
    Source sequence(s)
    AF074480, BG536615, CA312822
  2. NR_027626.1 RNA Sequence

    Status: VALIDATED

    Transcript Variant: This variant (2) contains alternate 5' and 3' exons, compared to variant 1.
    Source sequence(s)
    AL133268, BC032500, DA976765

RefSeqs of Annotated Genomes: Homo sapiens Annotation Release 110 details...Open this link in a new tab

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference GRCh38.p14 Primary Assembly


  1. NC_000006.12 Reference GRCh38.p14 Primary Assembly

    25081067..25138392 complement
    GenBank, FASTA, Sequence Viewer (Graphics)

Alternate T2T-CHM13v2.0


  1. NC_060930.1 Alternate T2T-CHM13v2.0

    24946777..25004128 complement
    GenBank, FASTA, Sequence Viewer (Graphics)

Suppressed Reference Sequence(s)

The following Reference Sequences have been suppressed. Explain

  1. NM_003570.2: Suppressed sequence

    NM_003570.2: This RefSeq record was removed by NCBI staff. Contact info@ncbi.nlm.nih.gov for further information.