Familial interstitial duplication of 11q; partial trisomy (11)(q13.5q21)

We report on a case of an interstitial duplication of 11q in a patient with developmental delay and in his moderately delayed mother. Partial trisomy 11q is well documented in the literature with most cases involving the distal region of the long arm of chromosome 11. In almost all cases, this trisomy is associated with monosomy of the second chromosome involved in the parental translocation. The most common, partial 11q and 22q trisomy syndrome, is observed in offspring of t(11;22)(q23;q11.2) carriers from a 3:1 tertiary trisomic malsegregation. We found only two previous reports of pure partial trisomy 11q in the literature. Comparison of the clinical findings of our patient and another single published report of duplication in the same segment of chromosome 11 suggests that the duplication of this region manifests mild phenotypic abnormalities.