Comprehensive diagnosis and genetic analysis of two children with ring chromosome 18
10.3760/cma.j.cn511374-20230626-00389
- VernacularTitle:18号环状染色体2例患儿的综合诊断与遗传学分析
- Author:
Zhe DING
1
;
Shiyue MEI
;
Bo ZHANG
;
Jinghui KONG
;
Lei LIU
;
Zhenhua ZHANG
;
Chaojie WANG
;
Yaodong ZHANG
Author Information
1. 郑州大学附属儿童医院（河南省儿童医院郑州儿童医院）儿科医学研究所 河南省儿童遗传代谢性疾病重点实验室，郑州 450018
- Keywords:
Ring chromosome 18 syndrome;
18q deletion syndrome;
White matter dysplasia;
Type 1 diabetes mellitus;
Copy number variation sequencing
- From:
Chinese Journal of Medical Genetics
2024;41(9):1110-1116
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To clarify the genetic diagnosis of two children with ring chromosome 18 and explore their mechanisms and clinical phenotypes.Methods:Two patients treated at the Children′s Hospital of Henan Province respectively in June 2022 and March 2023 were selected as the study subjects. Genetic testing and diagnosis were carried out through copy number variation sequencing (CNV-seq), G-banded chromosomal karyotyping, and whole exome sequencing (WES). This study was approved by the Children′s Hospital of Henan Province (Ethics No. 2023-K-075).Results:Child 1 had mainly manifested developmental delay, white matter hypoplasia, type 1 diabetes mellitus, and micropenis. He was found to have a chromosomal karyotype of 46, XY, r(18)(p11.21q22.1)[40]/46, XY[7], and CNV-seq results showed that he has a 14.86 Mb deletion at 18p11.21p11.32 and a 14.02 Mb deletion at 18q22.1q23. Child 2 had peculiar facial features, delayed white matter myelination, developmental delay, atrial septal defect, severe sensorineural deafness, and congenital laryngeal stridor. He was found to have a chromosomal karyotype of 46, XY, r(18)(p11.2q23). CNV-seq result proved that he had a 14.86 Mb deletion at 18p11.21p11.32 and a 20.74 Mb deletion at 18q21.32q23. WES has failed to detect single nucleotide variants (SNVs) in either child, but revealed a large segmental deletion at chromosome 18 in both of them.Conclusion:Both children were diagnosed with ring chromosome 18 syndrome. The different size of the deletional fragments in the 18q region and mosaicism of ring chromosome 18 in child 1 may underlay the variation in their clinical phenotypes. The type 1 diabetes mellitus and micropenis noted in both children are novel features for ring chromosome 18 syndrome.
