- Interstitial 2.2 Mb deletion at 9q34 in a patient with mental retardation but without classical features of the 9q subtelomeric deletion syndrome. Kleefstra, T., Koolen, D.A., Nillesen, W.M., de Leeuw, N., Hamel, B.C., Veltman, J.A., Sistermans, E.A., van Bokhoven, H., van Ravenswaay, C., de Vries, B.B. Am. J. Med. Genet. A (2006)