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Psychol Med. 2018 May;48(7):1201-1208. doi: 10.1017/S0033291717002665. Epub 2017 Sep 25.

Genetic risk scores and family history as predictors of schizophrenia in Nordic registers.

Author information

1
Department of Medical Epidemiology and Biostatistics,Karolinska Institutet,SE-17177 Stockholm,Sweden.
2
Campbell Family Mental Health Research Institute,Centre for Addiction and Mental Health,Toronto,Ontario,Canada.
3
NORMENT,KG Jebsen Centre for Psychosis Research,Institute of Clinical Medicine,University of Oslo and Oslo University Hospital,0424 Oslo,Norway.
4
Department of Medical Genetics,Oslo University Hospital,Oslo,Norway.
5
Estonian Genome Center,University of Tartu,Tartu,Estonia.
6
The Lundbeck Foundation Initiative for Integrative Psychiatric Research,iPSYCH,Denmark.

Abstract

BACKGROUND:

Family history is a long-standing and readily obtainable risk factor for schizophrenia (SCZ). Low-cost genotyping technologies have enabled large genetic studies of SCZ, and the results suggest the utility of genetic risk scores (GRS, direct assessments of inherited common variant risk). Few studies have evaluated family history and GRS simultaneously to ask whether one can explain away the other.

METHODS:

We studied 5959 SCZ cases and 8717 controls from four Nordic countries. All subjects had family history data from national registers and genome-wide genotypes that were processed through the quality control procedures used by the Psychiatric Genomics Consortium. Using external training data, GRS were estimated for SCZ, bipolar disorder (BIP), major depression, autism, educational attainment, and body mass index. Multivariable modeling was used to estimate effect sizes.

RESULTS:

Using harmonized genomic and national register data from Denmark, Estonia, Norway, and Sweden, we confirmed that family history of SCZ and GRS for SCZ and BIP were risk factors for SCZ. In a joint model, the effects of GRS for SCZ and BIP were essentially unchanged, and the effect of family history was attenuated but remained significant. The predictive capacity of a model including GRS and family history neared the minimum for clinical utility.

CONCLUSIONS:

Combining national register data with measured genetic risk factors represents an important investigative approach for psychotic disorders. Our findings suggest the potential clinical utility of combining GRS and family history for early prediction and diagnostic improvements.

KEYWORDS:

Family history; GWAS; genetic risk score; genome-wide association; schizophrenia

PMID:
28942743
DOI:
10.1017/S0033291717002665
[Indexed for MEDLINE]

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