TRISOMY 9

Prenatal detection of trisomy 9 has been reported previously (1-9). The severity of malformations of trisomy 9 mosaicism appears to be related to the proportion of trisomic cells in the population and especially to the presence of the long arm of chromosome 9 (10).

In contrast other workers have not found a clear relationship between the frequency of trisomic cells and the severity of the abnormalities observed (11).

• Craniofacial - Microcephaly, flat nasal bridge, epicanthic folds, micrognathia, low set ears and cleft palate.
• Bilateral cystic renal dysplasia, atretic ureters.
• Hepatic and pancreatic dysplasia.
• Congenital Heart Disease - Seen in about 2/3 of cases.
• CNS - Cystic dilatation of the 4th ventricle with lack of midline fusion of the cerebellum.
• Less frequent abnormalities include microphthalmia, corneal opacities, coloboma of the iris, callosal agenesis, cleft lip and / or palate, abnormal lobation of lungs, bowel malrotation, imperforate anus and vertebral anomalies.

REFERENCES

1. Benacerraf BR, Pauker S, Quade BJ et.al. Prenatal sonography in trisomy 9. Prenat Diagn 1992;12:175-181.
2. Bureau YA, Fraser W, Fouquet B. Prenatal diagnosis of trisomy 9 mosaic presenting as a case of Dandy-Walker malformation. Prenat Diagn 1993;13:79-85.
3. Hsu LYF, Perlis T. United states survey in chromosome mosaicism and pseudomosaicism in prenatal diagnosis. Prenat Diagn 1984;4:97-130.
4. Pfeiffer RA, Ulmer R, Kniewald A et.al. Prenatal diagnosis of trisomy 9 mosaicism possibly limited to fetal membranes. Prenat Diagn 1984;4:387-389.
5. Purvis-Smith SG, Saville T, Osborn RA. Prenatal diagnosis of trisomy 9 mosaicism. Pathology 1983;15:109.
6. Schwartz S, Ashai S, Meijboora EJ et.al. Prenatal diagnosis of trisomy 9 mosaicism. Prenat Diagn 1989;9:549-554.
7. Sherer DM, Wang N, THompson HO et.al. An infant with trisomy 9 mosaicism presented as a complete trisomy 9 by amniocentesis. Prenat Diagn 1992;12:31-37.
8. Smoleniec JS, Davies T, Lunt P et.al. Complex mosaicism associated with trisomy 9. Prenat Diagn 1993;13:211-213.
9. Zadeh TM, Peters J, Sandlin C. Prenatal diagnosis of mosaic trisomy 9. Prenat Diagn 1987;7:67-70.
10. Sutherland GR, Carter RF, Morris LL. Partial and complete trisomy 9: delineation of trisomy 9 syndrome. Hum Genet 1976;32:133-140.
11. Diaz-Mares L, Molina B, Carnevale A. Trisomy 9 mosaicism in a girl with multiple malformations. Ann Genet 1990;33:165-168.