Atypical genotype in a typical phenotype

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.