Objectives: This research aimed to harness this behavioural, biological and genetic heterogeneity as a method of creating a more powerful study, using latent class analysis to investigate the subtypes of autism.
Methods: Information was collected on a cohort of 92 Autistic children (ages 4-18yrs) regarding their family histories and development using a parental report questionnaire covering pregnancy, birth, early physical and behavioural development and abnormalities, other medical conditions, diagnosis, sibling and family conditions. Current behaviour and functioning were assessed using the Vineland Adaptive Behaviour Scales, Social Responsiveness Scales, Developmental Behaviour Checklist, Childhood Communication Checklist-2. Current physical development and the presence and status of Minor Physical Abnormalities (MPA’s) were assessed by a paediatrician using a pre-determined checklist. Information pertaining to their early development was collected from postnatal and early childhood records. All children were karyotyped and urine amino acid analysis used to screen for a variety of genetic disorders.
Results: Heterogeneity of individuals was determined across behavioural domains including functioning level, biological domains including head size, presence of minor physical abnormalities and abnormal skin pigmentation, and genetic polymorphism in both coding and non-coding regions including those of CFHR, FCGR and ApoBEC. This enabled us to determine the presence of ‘Autism Subtypes’ which may be informative in future autism investigations. Experimental genetic assays were carried out on DNA to determine haplotypes and polymorphisms in Autism related genes.
Conclusions: Focusing on conditions comorbid with autism as a clue to distinct latent classes may lead to sub-classifications of autism and thus more powerful phenotypic and genotype studies in the future.