Klinefelter's syndrome and Prader-Willi syndrome: a rare combination.

In this paper a review is presented of the rare combination of Klinefelter's syndrome and Prader-Willi syndrome (PWS) and a second case of this combination with a uniparental disomy (UPD) etiology of PWS is described. Patients outlined in all other 8 reports and the present case have a PWS phenotype. Virtually no information is available on the behavioral and psychopathological phenotype in this combination. The latter may be explained by the observation that psychiatric syndromes are especially prevalent in PWS patients with a UPD. It is concluded that instability in mood and behavior in this and other syndromes should be preferentially treated with mood stabilizing agents.