Phenotypic variations in X chromosome mutations: Two case reports

Abstract

Turner syndrome (TS) affects 1 in 2500 females. Monosomy X is the most common etiology, classically presenting with hypoestrogenemia and short stature. We present two cases of partial X chromosome deletions that do not reflect the typical phenotype of TS.Patient 1 presented at age 17 with primary amenorrhea, cognitive delay and tall stature. Patient 2 presented at age 16 with primary amenorrhea, normal intelligence and average stature.Patient 1's karyotype revealed isodicentric X chromosome [46 X, idic(X)(q21)]. Patient 2's karyotype revealed [46 X,del(X)(q13.3)]. The stature of these patients was not affected. Estrogen therapy was required to provide secondary sexual changes promote bone health.Advances in technology and reproductive health provide an opportunity to make more specific recommendations for patients previously mistakenly diagnosed with TS.

Non-mosaic X monosomy (77,X) in a female dog with signs of virilization

“…Recently, a random cohort of 2053 dogs, including 1281 females and 964 males, was screened with the use of an SNP microarray; a single case of X monosomy and a single case of X trisomy were found (Shaffer et al 2021). This finding shows that the frequency of X monosomy in dogs may be even higher than the incidence of this aneuploidy in humans, where it is called Turner syndrome (TS), which varies between 1/2500 and 1/4000 in live-born female infants (Dawkins et al 2018).…”