The ambiguity of freemartinism diagnosis in cattle revealed by cytogenetic and molecular techniques

Abstract

Nineteen heifers and three male co-twins, originating from heterosexual twin pregnancies, were analysed with the use of cytogenetic and molecular techniques. A large number (50-400) of Giemsa stained metaphase spreads were studied and the proportion of XX and XY cell lines was calculated. The presence of two genes - SRY and AMEL (AMELX and AMELY) - was also analysed. Both approaches facilitated the identification of the XX/XY chimerism in 17 females and three males. The proportion of the co-twin cell line ranged from 1 to 99%. In two females no chimerism was detected: (1) 60,XY male chromosome complement in all 400 metaphase spreads; SRY-positive, AMELY-positive, AMELX-positive and (2) 60,XX female chromosome complement in all 200 metaphase spreads; SRY-negative, AMELY-negative, AMELX-positive. The usefulness of different techniques for the diagnosis of freemartinism is discussed.