The study of a hermaphroditic sheep caused by a mutation in the promoter of SRY gene

Abstract

In mammals, sex-determining region Y (SRY) gene plays vital role as a transcription factor to regulate the expression of the genes contributing to development of male genitals. Any mutation disrupting expression of SRY gene can cause disorders of sex development (DSDs). In this study, the examination of a hermaphroditic (female-like) Shal sheep which was referred for infertility is described. Initially, the reproductive system of the sheep was histologically and anatomically assessed. Karyotyping was used to determine the real gender of the animal. Sex hormones including progesterone, estradiol, and testosterone were measured by enzyme-linked immunosorbent assay (ELISA). Eventually, promoter part and SRY gene were sequenced and aligned to detect any potential mutation using NCBI data base. Although anatomical inspection led to identification of uterus, ovary, and enlarged clitoris as well as testes in the sheep, the karyotyping results interestingly revealed that the animal was genetically a male. Although the sheep had both male and female gonads, there were no overt signs of reproductive behavior and gamete production was not observed. Plasma steroid hormone levels were reported to be at basal levels. Additionally, a mutation was detected on the promoter of the SRY gene. In conclusion, the case implies that mutation on the promoter part of SRY gene could disrupt sexual development of the fetus culminating in DSDs in the sheep.

Keywords: Disorders sex developments; Mutation; SRY gene; Shal sheep.