Prenatal diagnosis of isochromosome 20q in a fetus with vertebral anomaly and rocker-bottom feet

Abstract

Objective: Isochromosome of the long arm of chromosome 20 (i(20q)) is a rare structural abnormality in prenatal diagnosis. Thirty prenatal cases of mosaic i(20q) have been reported, among which only four are associated with fetal malformations. We describe a new prenatal case of i(20q) with fetal malformations. Materials and methods: We also observed a discrepancy between uncultured and cultured amniotic fluid cells by using conventional cytogenetic, fluorescence in situ hybridization and array-SNP analysis. Results: The short arm deletion of chromosome 20 arising from the isochromosome encompassed two candidate genes PAX1 and JAG1 involved in cranio-facial and vertebral development. Conclusion: The data would allow establishing a phenotype–genotype correlation. Thus, we proposed to define a recognizable syndrome combining cranio-facial dysmorphism, vertebral bodies' anomalies, feet and cerebral malformations.

Keywords

• Chromosomal microarray analysis
• Isochromosome 20q
• Uncultured and cultured amniotic fluid
• Fetal malformations