Chromosomal Abnormalities in Idiopathic Mental Retardation Patients at a Charity Center in Hamadan, Iran

Chromosomal aberrations are one of the most common causes of mental retardation (MR). 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. 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. 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. Two out 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. The presence of structural chromosomal abnormalities (4%) in the studied MR patient population emphasizes the importance of cytogenetic investigation for all idiopathic MR patients.