Genetic score backs schizophrenia spectrum

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By Eleanor McDermid, Senior medwireNews Reporter

Researchers report that polygenic scores derived from one well-characterized cohort of schizophrenia patients correspond to clinical diagnostic categories in another.

They believe that the findings are “congruent with an underlying, continuous liability distribution” and represent “preliminary, molecular validation of a common genetic basis for the schizophrenia spectrum disorders.”

Kenneth Kendler (Virginia Commonwealth University School of Medicine, Richmond, USA) and team constructed a polygene score using published results from the Psychiatric Genome-Wide Association Studies Consortium and applied it to participants of the Irish Study of High Density Schizophrenia Families (ISHDSF) study.

A total of 843 ISHDSF participants were included in the analysis, and their individual polygene scores increased according to how narrow their diagnoses were; in other words, how close they were to having “pure” schizophrenia.

The average polygene score was 1.59 in the narrow diagnostic category, which included schizophrenia, poor-outcome schizoaffective disorder, and simple schizophrenia, the team reports in Schizophrenia Bulletin. This was significantly higher than the scores for patients in all other diagnostic categories.

“The observed pattern is consistent with that expected under the hypothesis of the schizophrenia spectrum with the narrow category having the highest score and the score decreasing in a nearly monotonic function across the other diagnostic categories,” say the researchers.

The intermediate category included diagnoses such as schizotypal personality disorder, atypical psychosis, and good-outcome schizoaffective disorder. The average polygene score for people in this diagnostic category was 1.47, similar to the 1.48 seen for people in the broad/very broad category, which included disorders such as psychotic affective illness, schizoid personality disorder, major depression, and alcohol dependence.

The polygene score was lower again in family members with no psychiatric diagnosis, at 1.32, but this was still significantly higher than the score of 0.96 seen for 1794 controls.

“As would be expected for any reasonable model of genetic transmission, individuals who are unaffected but close relatives of multiple individuals with schizophrenia or schizophrenia spectrum disorders are at an elevated genetic risk,” comment Kendler et al.

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  1. Mohammed Athari Mohammed Athari United States says:

    These studies presume that contributions from genes to schizophrenia are varied with many different loci underlying the disease.  The penetrance of these supposedly genetic components is “highly” variable and many genes involved in ASD are also involved in intellectual disability and schizophrenia, further underscoring their lack of specificity in phenotypic expression.  Let me interpret the above.  We have no idea how or why we say what we say.  We basically look for some similarities, fill out some questionnaires, and then speculate and surmise conclusorily blaming our genes.

    We now know that neurotoxins (lead and mercury) cause injury to the brain, which manifest as complex disorders of the brain such as ADHD, low IQ, autism and schizophrenia. A group of real scientists found out that there were clusters of areas, old houses with lead paint or the communities surrounding a chemical or coal plant, where there was striking similarity of complex disorders of the brain between parents and their children! On another front, more real scientists began understanding and mapping out the human genome (GWAS), and their studies began finding that there are no genes for these complex disorders of the brain and that even if you clustered a million genes together, you still could not explain anything!

    We have been dumping insane amounts of toxins into our environment for the last century.  Psycho-socialists (eugenic movement) have been claiming, like the authors here, that “genes”, whatever that means, increased the likelihood of complex disorders of the brain.  What has been lacking from this irresponsible claim is any explanation as to how or why.

  2. Schiz Life Schiz Life United States says:

    This is great.  We all understand that schizophrenia is a constellation of symptoms and not any truly clear-cut illness.  Establishing the 'purity' will help us to configure treatment to each specific case instead of dealing in generalizations.  Good stuff!

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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