Abstract
Background: Chromosomal aberrations are one of the most common causes of mental retardation (MR).
Objectives: In this study, in order to identify the rate of chromosomal abnormalities in idiopathic MR, 50 MR patients at a charity
center in Hamadan, Iran, were investigated.
Methods: Fifty mentally retarded male patients without specific chromosomal abnormalities (e.g., Down syndrome, Fragile X syndrome,
and Klinefelter syndrome) were included in the study. Standard cytogenetic techniques and high resolution GTG banding
were performed on all the patients.
Results: All the patients were male, with a mean age of 37.12 years. Skeletal and facial abnormalities were found in 8% and 22% of
patients, respectively. All the patients showed a moderate to severe level of mental retardation. None of the patients had numerical
chromosome abnormalities. Twoout of the 50 patients (4%) demonstrated structural chromosomal abnormalities. One patient had
a paracentric inversion in chromosome 1, while the other had a pericentric inversion in chromosome 2.
Conclusions: The presence of structural chromosomal abnormalities (4%) in the studied MR patient population emphasizes the
importance of cytogenetic investigation for all idiopathic MR patients.