Analysis of Cytogenetic Variations in Down Syndrome Patients in Iran (۱۹۸۴-۲۰۲۱): Contributing Factors

Background: Chromosomal abnormalities are a significant cause of inherited disorders. Down syndrome (DS) is one of the most common congenital chromosomal disorders in newborns. This study aimed to determine the frequency and associated factors of cytogenetic variations of DS in Professor Farhoud's Genetic Clinic referrals from ۱۹۸۴ to ۲۰۲۱. Methods: A total of ۱۲۷۳ patients with DS referred to Professor Farhad Genetic Clinic for karyotyping during ۱۹۸۴-۲۰۲۱ were included. All patients with a clinical diagnosis of DS were selected using a census approach. DS was confirmed using chromosomal analysis and karyotyping of blood or amniotic fluid samples. Results: Of the ۱۲۷۳ patients with DS, ۱۲۰۲ (۹۵.۳۲%) were identified with trisomy ۲۱ karyotype. Forty-seven patients (۳.۷۳%) had various translocation types, and ۱۲ patients (۰.۹۵%) had mosaicism. Conclusion: Trisomy ۲۱ was the most prevalent cytogenetic variation of DS in all geographical regions of Iran. Trisomy ۲۱ karyotype was more common than Robertsonian translocation and mosaicism in all regions. Robertsonian translocation was more prevalent in the south and northwest of the country, while its association with fetal survival was not significant.

کلیدواژه ها:

Down syndrome ، chromosomal abnormalities ، cytogenetics ، chromosome ۲۱ ، mosaicism ، Robertsonian translocation