Polledness intersex syndrome in goats - molecular and histological aspects

Abstract

Polledness intersex syndrome (PIS) is a phenomenon associated with 2 distinct conditions occurring in goats, namely polledness and intersexuality. The first is a trait exhibiting complete dominance, whereas the latter is recessive. The extreme case of intersexualism is complete sex reversal, which is observed only in females (60,XX). The trait PIS is inherited in a recessive manner and caused by deletion of 11.7 kbp DNA on chromosome 1q43. Female goats with PIS exhibit a broad range of developmental abnormalities of the sexual system, from only subtle changes to complete sex reversal. The phenotypic diversity in goats with PIS is most likely an effect of complexity of the sexual differentiation process, in which the gene-dosage effect may potentially play a crucial role, in addition to the numerous molecular factors regulating the developmental pathway. The occurrence may explain different degrees of masculinization. Nevertheless, the sex reversal phenomenon appearing in female goats (60,XX) with PIS is not considered a serious problem in breeding programs because properly planned selection of individuals for reproduction can allow for complete exclusion of risk of occurrence of this syndrome in offspring. On the other hand, female goats with PIS are still one of the most suitable animal models for studying complex processes of determination and differentiation of sex in mammals.