Copy number variants are a substantial source of pathogenic or normal genome variations. Chromosomal imbalances of several megabasepair are normally harmful for the affected person. Still, rarely reported are so-called “unbalanced chromosome abnormalities” (UBCAs), which are either losses or gains or equally large genomic regions, but the carrier is only minimally clinically affected even no clinically affected. The knowledge of such UBCAs is imperative also in noninvasive prenatal testing (NIPT) or chromosomal microarray analysis.
A paternally inherited dup(18)(q11.1q11.2) was identified in a over two generations in a Chinese family. The affected region encompasses 25 genes, among which GATA6 is expressed in fetal endothelial cells and mesodermal cells. GATA6 duplications and /or mutations have been seen in cases with congenital heart disease but also non-affected individuals, suggesting incomplete penetrance and variable expressivity.
Duplications in the region of chromosome 18q11 have been rare reported previously in clinically healthy persons. Here a further family with an UBCA in 18q11 is added to the literature, suggesting a careful genetic counselling in prenatal diagnosis.