Atypical genotype in a typical phenotype

Diksha Shirodkar

doi:10.31579/2692-9759/068

Abstract

Introduction: Usually, onset of thelarche heralds puberty. Delayed puberty is worrisome and needs medical attention. Our patient in her late adolescence presented with primary amenorrhea, whose evaluation left us surprised. Case report: An eighteen-year-old scholastically backward girl, presented with complaints of not attaining menarche. Physical examination included a height of 156 cm(10th-25thcentile),weight 51 kg(50th centile), wide carrying angle, multiple nevi and a broad chest, however no other Turner stigmata was noted. Her sexual maturity rating (SMR) was A2P2B1 Laboratory investigations revealed increased gonadotropins (FSH:77mIU/ml; LH:25.4mIU/ml), low estradiol (14 pg/ml) and vitamin-D deficiency (21ng/ml). Ultrasonography of abdomen-pelvis showed small infantile uterus with streak ovaries. Karyotype (50 metaphases) demonstrated mosaicism [47,XXX (29)/45,X(19)/46,XX(2)]. Hormone replacement therapy and vitamin D replacement was initiated. Conclusion: 30-40% of the Turner syndrome are mosaics, the most common being 45,X/46,XX. Mosaicism is the presence of 2 or more cell lines with different chromosomal constitutions. The cell lines are derived due mostly to postzygotic mitotic nondisjunction. X/XX/XXX can present with or without classical turner stigmata. Trisomy X has a spectrum of presentation from normal menses and fertility to recurrent abortions and primary/secondary amenorrhea (primary ovarian insufficiency). Varied clinical phenotype due to three cell lines in a Turner mosaic makes this case unique.

Highlights

Whenever an adolescent girl presents with short stature, primary amenorrhea and absence of secondary sexual characteristics, the first diagnosis which comes to our mind is Turner syndrome (TS)
We present to you a case of an adolescent female who presented with primary amenorrhea, with a not-so classical genotype
The clinical presentation in our case was typical of a Turner phenotype which is consistent with gonadal dysgenesis causing primary amenorrhea, the absence of short stature could be attributed to the huge proportion of the trisomy X(47,XXX) cell line

Summary

Conclusion

This harps the fact that any adolescent presenting with delayed puberty has to be evaluated with a karyotype, even if she has classical Turner stigmata. Mosaicism is the one entity which will decide the age and the mode of presentation. More so, it is all the more essential for the karyotype in any patient with primary amenorrhea to look for Y cell line so as to prevent a gonadoblastoma in future. Trisomy X has a heterogenous presentation from normal menses, tall stature and normal fertility to recurrent abortions and primary/secondary amenorrhea (primary ovarian insufficiency). A mixed phenotype in our case due to. Three cell lines (Triple mosaic TS) in varying proportions makes this case unique

Introduction

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Discussion