Schizophrenia: sex and familial morbidity

Risk of schizophrenia in relatives of individuals affected by schizophrenia: A meta-analysis

A meta-analysis was conducted to estimate schizophrenia incidence in first-degree relatives (FDRs) of probands diagnosed with schizophrenia. The aim was to inform future schizophrenia research and improve accuracy of risk communication to patients. Schizophrenia risk in FDRs with 1 or 2 probands with schizophrenia was investigated by conducting a systematic review of cohort and case-control studies with the following criteria: published between 1977 and 2018; reported odds ratios (OR), relative risk (RR) or sufficient raw data to calculate OR or RR; used appropriate diagnostic criteria; and reported systematic proband recruitment and ascertainment of relatives. Studies were obtained via EMBASE and MEDLINE electronic database searches. From an initial 5755 articles, 19 met the inclusion criteria. Mean effect sizes across studies were estimated using random effects methods. Estimates for schizophrenia risk were OR = 7.69 (95% CI 5.11-11.56) for FDRs of one proband with schizophrenia compared to healthy control probands, increasing to OR = 11.11 (95% CI = 1.45-85.02) for FDRs with two probands with schizophrenia. These findings support the existing literature suggesting significant genetic liability for schizophrenia. The results can be used to educate individuals with a family history of schizophrenia about their risk.

Associations between risk factors for schizophrenia and concordance in four monozygotic twin samples

Concordance for schizophrenia is high in monozygotic twins but the extent to which concordance varies according to the presence of other schizophrenia risk factors is not well established. We aimed to investigate this in systematically ascertained twin samples. DSM-III-R/DSM-IV diagnoses were made from original data or published case histories from four systematically ascertained monozygotic twin samples. Probandwise concordance for schizophrenia was calculated according to the presence of psychotic disorder in first-degree relatives, birth order, gender, and age-at-onset. Logistic regression analysis was also performed to adjust for potential confounders. Psychotic disorder in parents and earlier age-at-onset were significantly associated with higher probandwise concordance for schizophrenia, including after adjustment for potential confounders. For example, when no parents had a psychotic disorder concordance was 34/88 (38.6%) versus 10/16 (62.5%) when one parent was affected; and for age-at-onset <23 years concordance was 25/46 (54.3%), declining to 13/44 (29.5%) for age-at-onset >30 years. These results are consistent with psychotic disorder in parents and age-at-onset being markers of the level of familial liability to schizophrenia and these factors may be useful in genetic counseling of monozygotic twins and in identifying and managing those at particularly high risk, if these findings are further replicated.

Twelve-month follow-up of family communication and psychopathology in children and adolescents with a first psychotic episode (CAFEPS study)

We analyzed the potential influence of family relationships and history of psychiatric disorders on the presentation and course of early psychotic disorders. We recruited 110 subjects aged 9-17 years with a first psychotic episode and 98 matched healthy controls, and followed them for 1 year. Data were collected through clinical interviews and the Parent-Adolescent Communication Inventory. A family history of psychosis-related disorders was more common in patients' families, with a five-fold higher risk for psychoses related disorders than families of healthy controls. If we consider psychoses related disorder in first-degree relatives, the risk is even higher, rising to 15-fold. The families of patients with a first psychotic episode score themselves worse in communication than the families of healthy controls. More problems in communication at baseline correlated with a higher degree of psychopathology and a lower clinical improvement after 12 months of follow-up.

Older paternal age strongly increases the morbidity for schizophrenia in sisters of affected females

The effect of a family history of schizophrenia on the risk for this disorder in the offspring has rarely been examined in a prospective population cohort accounting for the sex of the proband and the first-degree relatives, and certainly not with respect to later paternal age. The influence of affected relatives on offspring risk of schizophrenia was estimated using Cox proportional hazards regression in models that accounted for sex, relation of affected first degree relatives and paternal age in the prospective population-based cohort of the Jerusalem Perinatal Schizophrenia Study. Of all first-degree relatives, an affected mother conferred the highest risk to male and female offspring among the cases with paternal age <35 years, however, female offspring of fathers ≥35 years with an affected sister had the highest risk (RR = 8.8; 95% CI = 3.9-19.8). The risk seen between sisters of older fathers was fourfold greater than the risk to sisters of affected females of younger fathers (RR = 2.2, 95% CI 0.7-6.7). The test for interaction was significant (P = 0.03). By contrast, the risk of schizophrenia to brothers of affected males was only doubled between older (RR = 3.3, 95% 1.6-6.6) and younger fathers (RR = 1.6, 95% CI 0.7-3.5). The most striking finding from this study was the very large increase in risk of schizophrenia to sisters of affected females born to older fathers. The authors speculate that the hypothesized paternally expressed genes on the X chromosome might play some role in these observations.

Association study of DTNBP1 with schizophrenia in a US sample

BACKGROUND

Straub et al. (2002b) located a susceptibility region for schizophrenia at the DTNBP1 locus. At least 40 studies (including one study in US populations) attempted to replicate this original finding, but the reported findings are highly diverse and at least five pathways by which dysbindin protein might be involved in schizophrenia have been proposed. This study aimed to test the association in two common US populations by using powerful analytic methods.

METHODS

Six markers at DTNBP1 were genotyped by mass spectroscopy ('MassARRAY' technique) in a sample of 663 individuals, including 346 healthy individuals European-Americans (EAs) and 48 African-Americans (AAs), and 317 individuals with schizophrenia (235 EAs and 82 AAs). Thirty-eight ancestry-informative markers were genotyped in this sample to infer the ancestry proportions. Diplotype, haplotype, genotype, and allele frequency distributions were compared between the cases and controls, controlling for possible population stratification, admixture, and sex-specific effects, and taking interaction effects into account, using a logistic regression analysis (an extended structured association method).

RESULTS

Conventional case-control comparisons showed that genotypes of the markers P1578 (rs1018381) and P1583 (rs909706) were nominally associated with schizophrenia in EAs and in AAs, respectively. These associations became less or nonsignificant after controlling for population stratification and admixture effects (using structured association or regression analysis), and became nonsignificant after correction for multiple testing. However, regression analysis showed that the common diplotypes (ACCCTT/GCCGCC or GCCGCC/GCCGCC) and the interaction effects of haplotypes GCCGCC/GCCGCC significantly affected risk for schizophrenia in EAs, effects that were modified by sex. Fine-mapping using d or J statistics located the specific markers (d: P1328; J: P1333) closest to the putative risk sites in EAs.

CONCLUSION

This study shows that DTNBP1 is a risk gene for schizophrenia in EAs. Variation at DTNBP1 may modify risk for schizophrenia in this population.

Estimated yield of early detection of prodromal or first episode patients by screening first degree relatives of schizophrenic patients

Screening a population of relatives of current schizophrenic patients could be an efficient means to accrue a sample of early first episode or prodromal patients for a prediction study or an intervention study. The risk of new onset schizophrenia cases in any one year in a population of relatives depends on the number of schizophrenic probands and three additional factors: (1) the age of onset distribution for schizophrenia; (2) the lifetime risk of the at-risk group of relatives selected; and (3) the number of at-risk relatives per proband and their age distribution. Estimates are made for each of these parameters, and calculations are presented. The base model suggests that screening all siblings and children of patients with schizophrenia would yield approximately 19 new cases of schizophrenia per year per 10,000 relatives screened. The results of the calculation are relatively insensitive to reasonable variation of most model parameter estimates. The yield of new cases obtained by screening relatives of current patients appears to be low if the purpose is to recruit a sample for an early intervention study over a relatively short period of time.

mRNA expression of serotonin receptors of type 2C and 5A in human resting lymphocytes

We investigated the presence of mRNA for serotonin receptors of type 2C (5-HT(2C)) in resting lymphocytes by means of RT-PCR and Southern blotting analyses, given their possible role in the pathophysiology of anxiety and eating disorders. At the same time, we explored also the presence of the specific mRNA for 5-HT(5A) receptors, a novel subtype for which still no functional data exist. Healthy subjects and patients with obsessive-compulsive or bipolar disorders were included in the study. The results showed the presence of the specific mRNAs for both 5-HT(2C) and 5-HT(5A) receptors in resting lymphocytes of the three groups of subjects. An additional band was also observed after the amplification of the 5-HT(5A) cDNA in each sample. These findings, while revealing the presence of 5-HT(2C) and 5-HT(5A) receptor mRNAs in an easily available tissue, can be considered preliminary for future quantitative analyses in patients with different psychiatric conditions.

Narratives of twenty to thirty year outcomes in schizophrenia

This descriptive study objectively compares three decades in the life histories of women and men with schizophrenia treated continuously at one institution. On the basis of clinical observation, it was hypothesized that the first ten years of illness would be stormier for men, but that women would suffer more than their male counterparts as they began to approach the age of menopause. Eighty active patients with a current diagnosis of DSM-IV schizophrenia were identified. From this group, ten men and ten women, randomly selected, agreed to review and publication of their life stories in slightly altered form. These twenty patients and their current case managers were interviewed. Their medical records were reviewed and the course of selected predictor variables was charted on the Camberwell Assessment of Need (CAN) entry form. The entries on the CAN fluctuated markedly for most of the patients over the two to three decades of illness. Seven of the ten men were, as predicted, globally most severely ill during their first decade of illness and improved thereafter. By contrast, eight of the ten women appeared to suffer a relatively need-free first decade, followed by increasing disability over time. In this small group, which, because of the method of recruitment, excluded best and worst outcomes, factors such as onset age, duration of untreated prodrome, and early course of illness (as assessed by chart review) did not predict long-term outcome. On the other hand, substance abuse, social supports, and a family history of schizophrenia were more closely correlated with 20- to 30-year outcome status. The direct effect of female menopause on illness severity was not possible to gauge in this study, but alterations in hormones may have played a part in responsivity to family and social loss.