The phenotype of many inherited disorders tends to become progressively more severe and/or be expressed at a younger age as it is transmitted to successive generations of a pedigree. This phenomenon is called anticipation and has been reported to occur widely in the principal functional psychoses (schizophrenia and bipolar disorder), although it is possible that these findings are attributable to sampling biases.

Keywords: age at onset; bipolar disorder; disease severity; repeat expansion detection; schizophrenia

Figure 1.

Repeat expansion detection. (Figure reproduced with permission from Schalling et al. ).



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Further Reading

Margolis RL, McInnis MG, Rosenblatt A and Ross CA (1999) Trinucleotide repeat expansion and neuropsychiatric disease. Archives of General Psychiatry 56: 1019–1031.

Morel BA (1857) Traite des Degenerescences. Paris: JB Bailliere.

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Penrose LS (1948) The problem of anticipation in pedigrees of dystrophia myotonica. Annals of Eugenics 14: 125–132.

Vincent JB, Paterson AD, Strong E, Petronis A and Kennedy JL (2000) The unstable trinucleotide repeat story of major psychosis. American Journal of Medical Genetics – Seminars in Medical Genetics 97: 77–97.

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O'Donovan, Michael(Jul 2006) Anticipation. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0005228]