Tabriz University of Medical Sciences Journal of Research in Clinical Medicine 2717-0616 4 2 2016 05 31 Cytogenetic findings in patients with intellectual disability and/or multiple congenital anomalies 97 103 10.15171/jarcm.2016.016 EN Sima Mansoori Derakhshan Mahmoud Shekari Khaniani Journal Article 10.15171/jarcm.2016.016 2015 12 23 2016 01 23 Introduction: Chromosomal abnormalities are a major etiology of intellectual disability (ID) and multiple congenital anomalies (MCAs). Screening for chromosomal aberrations by clinical diagnostic techniques has been primarily performed through standard karyotyping. Methods: A cytogenetic study involving 1730 individuals with ID and/or MCA was conducted using lymphocyte culture and high-resolution G-banding method. Results: Various types of chromosomal abnormalities were detected in 440 patients (25.5%). Numerical and structural chromosomal abnormalities, respectively, were observed in 63.3% (278 out of 440) and 36.7% (162 out of 440) patients. Among the chromosomal abnormalities, sexual chromosomal abnormalities were found in some cases, and Klinefelter syndrome with 2.5% frequency was the most frequent sex chromosomal abnormality. Autosomal abnormalities were found in cases, and Down syndrome was the most frequent autosomal chromosomal abnormality occurring in 41.0% of detected abnormalities. Conclusion: The higher contribution of chromosome aberrations in the northwest of Iran indicates the importance of cytogenetic evaluation in the etiology of MCA and/or ID patients. Genetic counseling was provided to the family members to explain the recurrence risk as well as the need for prenatal diagnosis in subsequent pregnancies and management of patients by collected data bank.