Interstitial deletion 11q is when a part of the long arm of chromosome 11 is missing due to two breaks in the chromosome. The piece between the breaks is lost, but the very end of 11q is still there. The symptoms depend on where the breaks happen and how much of the chromosome is missing.

Sometimes, the symptoms can be similar to Jacobsen syndrome if the deletion overlaps with the same region. If the breaks are closer to the center of the chromosome, the symptoms can be different. Common features include intellectual disability, delayed growth, distinctive facial features, and organ malformations.