Segmental Cervical Aplasia in a Colombian Creole Mare with Mosaic X-Chromosome Aneuploidy.

The research paper discusses a rare case of a Colombian Creole mare, with an abnormal number of X-chromosomes, that shows signs of a reproductive condition where part of the cervix is missing.

Background

• The study focuses on a 4-year-old Colombian Creole mare brought in for diagnostic evaluation because the external opening of her cervix couldn’t be located during a uterine lavage treatment for uterine fluid accumulation.

Observations and Findings

• Upon clinical and ultrasonographic assessment of the genital tract, the ovaries were found to be of regular size with indications of normal ovarian activity.
• Despite this, an ultrasound identified granular free-floating fluid distending the uterus.
• The normal external cervical structure wasn’t visible upon vaginal examination. instead, the vagina ended in a blind bag with a small papilla and no evident external cervical opening (os).
• Cytological analysis of the uterine fluid, collected via transvaginal aspiration, presented findings in line with mucometra, a condition characterised by the accumulation of mucus in the uterus.

The Karyotype Analysis

• The karyotype analysis revealed an abnormal number of the X chromosome. Normally, the female horse has 32 pairs of autosomes and the sex chromosome pair (XX), but in this case, it was found to be mosaic with three different populations: a monosomy X (63,X), a normal diploid (64,XX) and a trisomy X (65,XXX), in ratios of 45%, 45% and 10% respectively.

Diagnosis

• Suspecting a congenital segmental cervical aplasia (part of the cervix missing from birth), the authors proposed that the condition might be related to the mosaic form of the X sex chromosome detected.
• This is first known case of this reproductive disorder seen in a mare with normal ovarian activity, but an confirmed aneuploidy (abnormal number of a certain chromosome) in the mosaic form of the X sex chromosome.