Rene Ehlers

Advancing paternal age at birth is associated with poorer social functioning earlier and later in life of schizophrenia patients in a founder population.

Consistent associations have been found between advanced paternal age and an increased risk of psychiatric disorders, such as schizophrenia, in their offspring. This increase appears to be linear as paternal age increases. The present study investigates the relationship between early deviant behaviour in the first 10 years of life of patients as well as longer term functional outcome and paternal age in sporadic Afrikaner founder population cases of schizophrenia. This might improve our understanding of Paternal Age-Related Schizophrenia (PARS). Follow-up psychiatric diagnoses were confirmed by the Diagnostic Interview for Genetic Studies (DIGS). An early deviant childhood behaviour semi-structured questionnaire and the Specific Level of Functioning Assessment (SLOF) were completed. From the logistic regression models fitted, a significant negative relationship was found between paternal age at birth and social dysfunction as early deviant behaviour. Additionally, regression analysis revealed a significant negative relationship between paternal age at birth and the SLOF for interpersonal relationships later in life. Early social dysfunction may represent a phenotypic trait for PARS. Further research is required to understand the relationship between early social dysfunction and deficits in interpersonal relationships later in life.

Phenotypic features of patients with schizophrenia carrying de novo gene mutations : a pilot study

Genome-wide scans have revealed a significant role for de novo copy number variants (CNVs) and Single Nucleotide variants (SNVs) in the genetic architecture of schizophrenia. The present study attempts to parse schizophrenia based on the presence of such de novo mutations and attempts genotype-phenotype correlation. We examined phenotypic variables across three broad categories: clinical presentation, premorbid function, disease course and functional outcome and compared them in individuals with schizophrenia carrying either a de novo CNV, a de novo SNV, or no de novo mutation. Work skills were worst affected in patients carrying de novo CNVs. More learning disabilities were found in subjects carrying de novo SNVs. Patients with either mutation had older parents at birth and worse functional outcome as measured by SLOF scores. We found no relation between treatment resistance and the presence of de novo mutations. The combined consideration of the functional outcome scores and early deviant behaviours was found to have higher predictive value for underlying genetic vulnerability. Due to the rare nature of the de novo mutations the sample sizes studied here were small. Despite this, valuable phenotypic characteristics were identified in schizophrenia patients carrying de novo mutations and studying larger samples will be of interest.

S189. CARVING A MORE SPECIFIC SUBTYPE OF SCHIZOPHRENIA FOR GENETIC STUDIES: SPORADIC SCHIZOAFFECTIVE BIPOLAR TYPE

Abstract Background Schizophrenia is a heterogeneous group of disorders. The familial-sporadic distinction has been considered under a range of genetic models. Research supports a strong association of de novo copy mutations with sporadic schizophrenia. The aim of the study was to determine a more homogenous phenotype for genetic research via comparison of various clinical and socio-demographic variables in familial and sporadic schizophrenia. Methods A cross-sectional observational design was used. This study included 384 participants with schizophrenia/schizoaffective disorder from an Afrikaner founder population in South Africa that previously participated in genetic research. A comprehensive data capturing sheet was completed from a pre-existing database that contains information obtained from the Diagnostic Interview for Genetic Studies, chronological clinical summary reports and additional sources of information. The study protocol was approved by the Research Ethics Committee from the Faculty of Health Sciences at the University of Pretoria. Logit models were fitted using the backward elimination procedure to investigate relationships where the dependent variable was binary. Odds ratio estimates were calculated for independent variables that were significant in the model. The Kruskal-Wallis test was conducted to compare the means of groups. For cases where there were significant differences a post-hoc test with a Bonferroni correction was done to determine which groups differ significantly. Results There were 214 familial and 170 sporadic subjects. 279 had a diagnosis of schizophrenia, 66 schizoaffective, bipolar type and 39 schizoaffective disorder, depressive type. 242 were male and 142 female. The age at onset of the primary psychiatric diagnosis, season of birth, co-morbid diagnoses, symptomatology, suicidality history and marital status weren’t significantly different when considering the combined schizophrenia/schizoaffective disorder group and its relationship to familiality. Early deviant behaviour was however decreased in the sporadic group. These findings were replicated when analysing schizophrenia independently from schizoaffective disorder. The sporadic schizoaffective disorder, bipolar type did however have a significantly lower age at onset (mean 20.18 versus 25.07 years), 8.8 times more hallucinations, 6.6 times more odd behaviour before the age of 10 and were 2.8 times more likely to be single. The bipolar type also had 2.9 times more suicide attempts as opposed to ideation. This finding wasn’t statistically significant. The sporadic schizoaffective group overall was 2.2 times more likely to abuse substances. The depressive type didn’t differ significantly with regards to age at onset, season of birth, co-morbidities, early deviant behaviour, symptomatology, suicidality or marital status. Discussion The combined schizophrenia/schizoaffective group didn’t differ significantly, nor did schizophrenia and schizoaffective disorder depressive type when analysed independently. The sporadic schizoaffective bipolar type differed significantly on multiple important variables that suggest a poorer prognosis and increased disease severity. The sporadic schizoaffective bipolar type forms a more homogenous group, with genetic studies hinting at relatively specific genetic risk factors. Studies elucidating the genetic architecture of this group could prove invaluable in clarifying the aetiology of schizophrenia.

Increased risk of suicide in schizophrenia patients with linkage to chromosome 13q

We link schizophrenia in families from the genetically isolated South African Afrikaner population to chromosome 13q (n =51), 1p (n =23) and combined 13q & 1p (n =18). Patients with linkages to chromosome 13q were 4.16 times more likely to meet diagnostic criteria for schizoaffective disorder compared to patients with linkage to 1p. A third of patients with linkage to both 13q &1p met diagnostic criteria for SAD. There was a significant positive relationship between suicidality and a diagnosis of schizoaffective disorder. Identifying linkage to chromosome 13q may be informative in identifying suicide risk early and prevent morbidity and mortality in schizophrenia patients.

Changes in the mandibular angle during adulthood in South Africans

The purpose of this study was to measure the mandibular angle as a reflection of the biomechanical forces acting on the mandible and relate it to aging and loss of teeth.