40 Mb duplication in chromosome band 5p13.1p15.33 with 800 kb terminal deletion in a foetus with mild phenotypic features.

Large duplication of the short arm of chromosome 5 is a rare condition normally associated to severe phenotype anomalies including heart and brain malformations. We report a prenatal case of a large 5p duplication with sub-telomeric deletion in a foetus with very mild phenotypic abnormalities. Foetal ultrasonographic examination at 22 weeks of gestation showed short femur, clubfeet, pielectasy, and facial dysmorphisms. Chromosome investigations revealed an inverted duplication of the short arm of chromosome 5 from 5p13.1 to 5p15.33 and a 800 kb deletion at 5pter. The absence of severe anomalies such as cardiac and cerebral defects, observed so far in all large 5p duplications, and the comparison to previous cases described both in literature and in DECIPHER database suggest that the critical region for the severe phenotype in 5p duplication syndrome might be smaller than that previously described, excluding half of the 5p13 band. This might help in prenatal genetic counselling.