Abstract
IntroductionThere is a dearth of data on heritability of schizophrenia in Africa. The few African studies that addressed familial psychiatric morbidity in schizophrenia involved relatively small sample sizes and addressed psychiatric morbidity only in first-degree relatives. The present study sought to improve upon the methodology of previous African studies, and widen the scope to second- and third-degree relatives with a view to enriching the field of genetic epidemiology in Africa.MethodsThis study elicited information on the morbid risk of schizophrenia amongst 5259 relatives of schizophrenia probands (n = 138) and 6734 relatives of healthy controls (n = 138) through direct interview of patients, available relatives of patients and controls. Diagnosis of probands was confirmed using Mini International Neuropsychiatric Interview. Through a direct interview of 138 patients and their available relatives, a family history approach using the Family Interview for Genetic Studies was utilised to obtain information on the morbid risk for all relatives that could be recalled. The same approach was utilised for the interview of the controls (aged 45 years and above) and their relatives. Morbid risk estimates were calculated using the Weinberg shorter method.ResultsMorbid risk for schizophrenia in the first-, second- and third-degree relatives of schizophrenia probands was 10.9% (95% confidence interval [CI] = 10.6–11.2), 4.2% (95% CI = 4.1–4.3) and 3.9% (95% CI = 3.6–4.2), respectively, compared with 2.6% (95% CI = 2.5–2.7), 1.6% (95% CI = 1.5–1.7) and 1.5% (95% CI = 1.4–1.6), respectively, of the healthy control group.ConclusionThe findings support the widely noted impression that schizophrenia significantly aggregates in families of schizophrenia probands more than healthy controls.
Highlights
There is a dearth of data on heritability of schizophrenia in Africa
It is of more interest to know the lifetime prevalence than the point prevalence; but even lifetime prevalence is not a wholly satisfactory statistic because some family members at the time of study will be unaffected but may develop the disorder at a future date, and others may have already died unaffected.[1]
The disorder is largely considered to have a genetic basis, with genetic factors and geneenvironment interactions contributing over 80% of the liability to schizophrenia.[8,9]
Summary
The few African studies that addressed familial psychiatric morbidity in schizophrenia involved relatively small sample sizes and addressed psychiatric morbidity only in first-degree relatives. The present study sought to improve upon the methodology of previous African studies, and widen the scope to second- and third-degree relatives with a view to enriching the field of genetic epidemiology in Africa. Assessment of lifetime morbid risk is an integral part of the epidemiologic assessment of many diseases and disorders.[2] Lifetime morbid risk is usually defined and determined by the Kaplan-Meier product limit estimator[3] and Weinberg method[4,5] as the probability of a person developing a disorder during a specified period of his or her life or up to a specified age. Schizophrenia is a heterogeneous group of disorders affecting about 1% of the general population.[6,7] The disorder is largely considered to have a genetic basis, with genetic factors and geneenvironment interactions contributing over 80% of the liability to schizophrenia.[8,9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The South African journal of psychiatry : SAJP : the journal of the Society of Psychiatrists of South Africa
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
