A Case of Trisomy 9 Mosaicism Mimicking Smith-Lemli-Opitz Syndrome

ABSTRACT

Trisomy 9 mosaicism is a disease characterized not only by intrauterine growth retardation and mental retardation but also congenital heart defects, musculoskeletal, genitourinary and CNS anomalies, as well as craniofacial anomalies such as microcephaly, micrognathia, narrowed temples, prominent occiput, broad-based nose with bulbous tip, low set ears, deeply set eyes, short palpebral fissure and small mouth. This syndrome was first reported back in 1973 by Haslam and others, and has hardly ever been reported since. In Korea, a complete form of trisomy 9 syndrome was first reported in 1998 by Chun and others, but trisomy 9 mosaicism has not been reported yet. We recently experienced a case with a patient who was most likely suspected as diet therapy requiring Smith-Lemli-Opitz Syndrome(SLO), since the patient had unilateral ptosis, hypospadias, micrognathia, simian crease, and low set ears, which are the characteristics not yet reported as trisomy 9 mosaicism, but most similar to Smith-Lemli-Opitz syndrome. Also, the patient did not show the typical characteristics of trisomy 9 mosaicism such as broad nose or enophthalmosis. However, further evaluation was taken in order to make the correct diagnosis, and the serum cholesterol level of the patient was shown to be normal, which implied normal cholesterol metabolism, but the chromosomal studies of the patient confirmed the karyotype of 47,XY,+9/46,XY, which proved that the patient has trisomy 9 mosaicism.