amorphn.
/ˈeɪmɔːf/, /əˈmɔːf/, U.S. /ˈeɪˌmɔrf/, /əˈmɔrf/ Genetics.
A mutant allele which is inactive and fails to produce a detectable product compared with the wild-type allele. Cf. amorphic adj. 3.
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the world > life > biology > biological processes > genetic activity > genetic components > [noun] > allele > types of allele
dominant1900
unit character1902
multiple allelomorph1913
lethal1917
marker1930
multiple allele1930
amorph1932
hypomorph1932
neomorph1932
isoallele1943
hypermorph1949
1932 H. J. Muller in Proc. 6th Internat. Congr. Genetics I. 236 The hypomorphs and amorphs are just the kind of mutants which the few remaining advocates of the presence-and-absence hypothesis..require as evidence.
1949 C. D. Darlington & K. Mather Elements of Genetics vii. 152 Far from removing bristles, scute-I helps to produce them. It does the same job as the wild type, but less than half as effectively. Such a gene Muller calls a hypomorph or, in the extreme case, when it does nothing, an amorph.
1993 R. L. Malmberg in B. R. Glick & J. E. Thompson Methods in Plant Molecular Biol. & Biotechnology ii. 12 It is easy to imagine that neomorphs and hypermorphs might be dominant mutants, whereas hypomorphs and amorphs would be expected to be recessive.
2004 Proc. National Acad. Sci. U.S.A. 101 17222/1 Mutations of the RH gene resulting in the total lack of Rh protein and only a reduced expression of RhAG (20% of normal) define Rhnull as the amorph type.
This entry has been updated (OED Third Edition, September 2019; most recently modified version published online December 2021).
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n.1932