RGD Reference Report - Amnionless, essential for mouse gastrulation, is mutated in recessive hereditary megaloblastic anemia. - Rat Genome Database

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Amnionless, essential for mouse gastrulation, is mutated in recessive hereditary megaloblastic anemia.

Authors: Tanner, SM  Aminoff, M  Wright, FA  Liyanarachchi, S  Kuronen, M  Saarinen, A  Massika, O  Mandel, H  Broch, H  De la Chapelle, A 
Citation: Tanner SM, etal., Nat Genet. 2003 Mar;33(3):426-9. Epub 2003 Feb 18.
RGD ID: 1599101
Pubmed: PMID:12590260   (View Abstract at PubMed)
DOI: DOI:10.1038/ng1098   (Journal Full-text)

The amnionless gene, Amn, on mouse chromosome 12 encodes a type I transmembrane protein that is expressed in the extraembryonic visceral layer during gastrulation. Mice homozygous with respect to the amn mutation generated by a transgene insertion have no amnion. The embryos are severely compromised, surviving to the tenth day of gestation but seem to lack the mesodermal layers that normally produce the trunk. The Amn protein has one transmembrane domain separating a larger, N-terminal extracellular region and a smaller, C-terminal cytoplasmic region. The extracellular region harbors a cysteine-rich domain resembling those occurring in Chordin, found in Xenopus laevis embryos, and Sog, found in Drosophila melanogaster. As these cysteine-rich domains bind bone morphogenetic proteins (Bmps), it has been speculated that the cysteine-rich domain in Amn also binds Bmps. We show that homozygous mutations affecting exons 1-4 of human AMN lead to selective malabsorption of vitamin B12 (a phenotype associated with megaloblastic anemia 1, MGA1; OMIM 261100; refs. 5,6) in otherwise normal individuals, suggesting that the 5' end of AMN is dispensable for embryonic development but necessary for absorption of vitamin B12. When the 5' end of AMN is truncated by mutations, translation is initiated from alternative downstream start codons.

RGD Manual Disease Annotations    Click to see Annotation Detail View
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
megaloblastic anemia susceptibilityIAGP 1599101 RGD 
megaloblastic anemia susceptibilityISOAMN (Homo sapiens)1599101; 1599101 RGD 

Objects Annotated

Genes (Rattus norvegicus)
Amn  (amnion associated transmembrane protein)

Genes (Mus musculus)
Amn  (amnionless)

Genes (Homo sapiens)
AMN  (amnion associated transmembrane protein)


Additional Information