ISSN:
1573-3297
Keywords:
recurrence risks
;
schizophrenia
;
single-major-locus model
;
multifactorial-polygenic model
;
multiple-threshold models
;
pedigree analysis
;
genetic counseling
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Psychology
Notes:
Abstract A trait such as schizophrenia, for which there is evidence of a strong genetic component but no fit to simple Mendelian modes of inheritance, presents several problems to the genetic counselor. Counseling with average empirical figures ignores specific family history and the possibility of genetic heterogeneity, yet precise estimates of risk are not possible since the mode of inheritance is not known. Two other complicating factors are present: (1) adoption studies suggest that a schizophrenia spectrum of phenotypes with a common genetic basis may exist, and (2) analysis of the family data on schizophrenia has shown almost equivalent fit to extremely different genetic models, i.e., the single-major-locus (SML) and the multifactorial-polygenic (MFP) models. Using two solutions to the SML model and a single MFP solution, we have incorporated thresholds for two milder “spectrum” phenotypes, borderline schizophrenia and schizoid personality, and computed the recurrence risks predicted by these models in several hypothetical pedigrees. The results demonstrate that (1) recurrence risks for schizophrenia are frequently model dependent even when those models fit the available data equally well, (2) when a schizophrenia spectrum is assumed it is extremely important to make precise diagnoses in relatives close to the individual at risk, and (3) collection of a more complete family history may appreciably alter the computed recurrence risk. These findings illustrate the inadequacies of current empirical data for genetic counseling for schizophrenia.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01066977
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