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 mosaicis