Anomalous inheritance of a paternally derived trophoblast antigen.

The research investigates a phenomenon where a specific paternally derived antigen, R80K, is disproportionately inherited in horse offspring, potentially leading to recurrent spontaneous abortions.

Objective and Background

• The objective of this study was to understand the anomalous inheritance of a paternally derived antigen, R80K, and its possible association with recurrent spontaneous abortions.
• These spontaneous abortions occur in 1 in 500 random matings and typically result in the abortion of all pregnancies.
• The researchers hypothesized that if a woman lacks antibodies to a specific paternal antigen, it could potentially cause these spontaneous abortions.

Methods

• The researchers prepared microvesicles from horse placentae.
• An acid-eluted IgG antibody was isolated from the R80K antigen and used to type the remaining R80K antigen on the vesicles or on peripheral blood leucocytes (white blood cells).

Results

• In several horse families, all the half-siblings shared the same paternal R80K alloantigen.
• In an extended horse family descended from the stallion Nearco, three different types of antigens, or allotypes, were found.
• The allele usually present was the grandpaternal one, however exceptions were seen where the other paternal allele was transmitted.
• Regardless of which allele was transmitted, all the offspring possessed the same alloantigen. The probability of this happening randomly was calculated to be 2(-45), an extremely low probability.

Conclusions

• The researchers concluded that because only one paternal allotype is present in all offspring, the absence of an antibody to the R80K antigen could result in the loss of all pregnancies instead of only half, contradicting their initial assumption.
• This study sheds light on the role of paternally-derived antigens and the potential genetic factors behind recurrent spontaneous abortions in horses.