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.).



Asherson P, Walsh C, Williams J, et al. (1994) Imprinting and anticipation – are they relevant to genetic studies of schizophrenia? British Journal of Psychiatry 164: 619–624.

Gorwood P, Leboyer M, Falissard B, et al. (1996) Anticipation in schizophrenia: new light on a controversial problem. American Journal of Psychiatry 153: 1173–1177.

Huang J and Vieland V (1997) A new statistical test for age‐of‐onset anticipation: application to bipolar disorder. Genetic Epidemiology 14: 1091–1096.

Lindblad K, Nylander P‐O, Zander C, et al. (1998) Two commonly expanded CAG/CTG repeat loci: involvement in affective disorders? Molecular Psychiatry 3: 405–410.

McInnis MG, McMahon FJ, Chase GA, et al. (1993) Anticipation in bipolar affective disorder. American Journal of Human Genetics 53: 385–390.

McInnis MG, McMahon FJ, Crow T, Ross CA and De Lisi LE (1999) Anticipation in schizophrenia: a review and reconsideration. American Journal of Medical Genetics and Neuropsychiatric Genetics 88: 686–693.

O'Donovan MC and Owen MJ (1996) Dynamic mutations and psychiatric genetics. Psychological Medicine 26: 1–6.

O'Donovan MC, Guy C, Craddock N, et al. (1996) Confirmation of association between expanded CAG/CTG repeats and both schizophrenia and bipolar disorder. Psychological Medicine 26: 1145–1153.

Penrose LS (1991) Survey of cases of familial mental illness. European Archives of Clinical Neuroscience 240: 314–324.

Ross CA (1999) Schizophrenia genetics: expansion of knowledge? Molecular Psychiatry 4: 4–5.

Schalling M, Hudson TJ, Buetow KH and Housman DE (1993) Direct detection of novel expanded trinucleotide repeats in the human genome. Nature Genetics 4: 135–139.

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.

Mott FW (1910) Hereditary aspect of nervous and mental diseases. British Medical Journal 2: 1013–1020.

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.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

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