Frequency and Distribution of Incidental Chromosomal Abnormalities Detected by Peripheral Blood Karyotyping: A Retrospective Study

Abstract

Objective: This study aims to examine the frequency and distribution of incidental chromosomal abnormalities identified through peripheral blood karyotype analysis and to evaluate their associations with sex, age, and chromosomal characteristics.

Methods: This retrospective study conducted an analysis of 2397 peripheral blood karyotype assessments carried out between September 2023 and February 2025. The study employed conventional lymphocyte culture and G-banding techniques, with karyotypes characterized in accordance with the International System for Human Cytogenomic Nomenclature (ISCN) 2024 guidelines. Chromosomal abnormalities that did not satisfy clinical reporting criteria were systematically documented. Detection rates were evaluated and compared across different sex and age groups, as well as chromosomal categories, utilizing chi-square tests and linear trend analysis.

Results: A total of 511 cases of incidental chromosomal abnormalities were identified, yielding an overall detection rate of 21.32%. No statistically significant difference was observed in the detection rates of abnormalities between females and males (p > 0.05). However, significant differences were noted among various age groups, with detection rates exhibiting an increasing trend with advancing age (p < 0.05). The distribution of abnormalities was uneven across chromosomes, predominantly concentrated in the C and D chromosome groups. Chromosomes 7, 9, and 14 were the most frequently affected. The most prevalent types of abnormalities included balanced translocations, deletions, and inversions, with t(7; 14) and del(9) (q13) being the most commonly observed. Additionally, 23 marker chromosomes were identified, displaying considerable morphological variability.

Conclusion: Incidental chromosomal abnormalities identified through peripheral blood karyotype analysis exhibit nonrandom distributions associated with variables such as age and specific chromosomes. These low-frequency occurrences may represent underlying somatic chromosomal variation and offer valuable reference data for the interpretation of karyotypes and the enhancement of laboratory quality control.

Keywords: clinical genetics; incidental chromosomal abnormalities; karyotype analysis; peripheral blood; retrospective study.