Very Low Level Mosaicism of Trisomy 13 in Prenatal Diagnosis:
Who Should Decide?
Ahmet DURSUN1, Davut GÜL2, Muhterem BAHÇE2, Yusuf TUNCA2, Melih ALÖMEROĞLU3
Ankara-Turkey
Phenotypic outcome and clinical effect of mosaic of trisomy 13 is not clear yet. Eventhough, there is a suggested relationship between the percentage of mosaicism and clinical appreance, literature reports a wide range of possibilities from normal intelligence to as severe as full. This makes genetic counselling after prenatal diagnosis of mosaic 13 particularly difficult. A 27 year old pregnant with normal serum screening result for Down's syndrome is admitted. Amniocentesis was performed due to mother anxiety Cytogenetic analysis and FISH was performed. Four out of 30 metaphases had trisomy 13 from first culture and FISH analysis performed from amniotic fluid cell culture and cord blood. Two out of 250 from amniocentesis and 3 out of 500 from cord blood metaphases had trisomy 13. Conclusion: We here report a case of mosaic trisomy 13 in which high risk of prenatal screening, prenatal ultrasound abnormalities were not observed and post-mortem histo-pathological examination was normal.Genetic counselling was not straightforward and family decided to end the pregnancy.
(Gynecol Obstet Reprod Med 2005; 11:57-58)
Key Words: Mosaicism, Trisomy 13, Prenatal diagnosis, Genetic counselling
