Trisomy 18 mosaicism associated with secondary amenorrhea: ratios of mosaicism in different samples and complications.

A 28-year-old woman who complained of irregular menstruation was diagnosed as suffering from trisomy 18 mosaicism. She was karyotyped because of her characteristic face, mild mental retardation and aberrant hyperpigmentation of the skin. Her motor function was within normal range. Physical and laboratory examinations, however, revealed obesity, short stature, minor anomalies of the fingers, many areas of hyperpigmentation on the trunk and the hips, hypergonadotropinemia, diabetes mellitus, liver dysfunction, and hyperlipidemia. The ratios of normal/trisomy 18 were 4:135 in blood lymphocytes, 3:11 in a hyperpigmented area of the skin, 20:0 in a normally pigmented area of the skin, and 14:6 in ascitic cells. Laparoscopy revealed that her ovaries contained neither follicles nor germ cells.