Identification of Y Chromosomal Material in Turner Syndrome by Fluorescence In Situ Hybridisation (FISH)

Turner syndrome is one of the most common chromosomal abnormalities affecting newborn females. More than half of patients with Turner syndrome have a 45X karyotype The rest of the patients may have structurally abnormal sex chromosomes or are mosaics with normal or abnormal sex chromosomes. Mosaicism with a second X sex chromosome is not usually of clinical significance. However, Turner syndrome patients having a second Y chromosome or Y chromosomal material are at risk of developing gonadoblastoma later in life. The aim of this study is to compare the results of conventional (karyotyping) and molecular cytogenetics (FISH), and discuss the advantages and limitations in the diagnosis of Turner syndrome. We also aim to compare the degree of mosaicism identified using conventional cytogenetics and FISH techniques. Conventional cytogenetics and FISH analyses were performed on eight peripheral blood samples of patients with Turner syndrome collected between 2004 and 2006. From this study, two out of eight patients with Turner syndrome were found to have the sex determining region on the Y chromosome (SRY) gene by FISH analysis. Our results showed that the rate of detection of mosaic cases in Turner syndrome was also increased to 88% after using the FISH technique. We concluded that FISH is more superior to conventional cytogenetics in the detection of the Y chromosomal material. FISH is also a quick and cost effective method in diagnosing Turner syndrome and assessing the degree of mosaicism.