OMIA:000393 : Tetragametic chimerism (including Freemartin)

Categories: Reproductive system phene

Cross-species summary: This is a type of sex chromosome difference of sexual development (DSD). Tetragametic chimerism is a rare, sex chromosome difference of sex development characterized by the two different haploid sets of maternal and paternal chromosomes and variable phenotype - from normal male or female genitalia, to different degrees of ambiguous genitalia, and often infertility. Also, in the cases of monochorionic dizygotic twins, it can be confined to blood of both twins. [updated from Orphanet : 199310 ] Freemartin or free-martin is an infertile female animal which is the twin of a male animal whose anti-Müllerian hormones affected its development in utero. Genetically the animals are chimeric (microchimerism, XX/XY leukocyte chimerism) - some stem cells from the male twin are received during in utero development via vascular connections between placentas. The condition is mostly reported in ruminants due to their multicotyledonary placenta type. Phene was renamed to 'Tetragametic chimerism' [16/11/2022]

Species in which this phene is found:
dog (Canis lupus familiaris)
horse (Equus caballus)
pig (Sus scrofa)
red deer (Cervus elaphus)
taurine cattle (Bos taurus)
sheep (Ovis aries)
bighorn sheep (Ovis canadensis)
water buffalo (Bubalus bubalis)

Edit History


  • Created by Frank Nicholas on 03 May 2005
  • Changed by Imke Tammen2 on 13 Oct 2022
  • Changed by Imke Tammen2 on 16 Nov 2022
  • Changed by Imke Tammen2 on 15 Feb 2023
  • Changed by Imke Tammen2 on 28 Sep 2023