Cytogenetic, Molecular, and Phenotypic Characterization of a Patient with de novo Derivative Chromosome 18 and Review of the Literature

Cytogenet Genome Res. 2019;159(2):74-80. doi: 10.1159/000503574. Epub 2019 Oct 26.


We present a patient with a de novo derivative chromosome 18 which includes a terminal deletion of 18p and a terminal duplication of 18q accompanied by a cryptic duplication of 18p. The girl had mild dysmorphic features such as micro-retrognathia, upslanted palpebral fissures, bilateral epicanthus, high palate, low-set ears, short neck, and full cheeks. She also had an H-type tracheoesophageal fistula which required surgery. Her cognitive and motor skills were delayed. Karyotype analysis showed an additional segment on the short arm of chromosome 18. Chromosomal microarray revealed a 7.3-Mb terminal loss from 18p11.32 to 18p11.23, a 22.2-Mb terminal gain from 18q21.31 to 18q23, and a 3.9-Mb interstitial gain from 18p11.22 to 18p11.21. We hypothesize that the mother has gonadal mosaicism for normal chromosome 18, der(18)dup(p11.22p11.21), and der(18)dup(p11. 22p11.21)inv(18)(p11.22q21.31), or both the terminal del/dup and the interstitial duplication occurred simultaneously.

Keywords: Derivative chromosome 18; Genotype-phenotype correlation; Partial dup(18q)/del(18p); Tracheoesophageal fistula.

Publication types

  • Case Reports

MeSH terms

  • Chromosome Deletion
  • Chromosomes, Human, Pair 18 / genetics*
  • Cytogenetics / methods
  • Female
  • Humans
  • Infant
  • Karyotyping / methods