A review of the risk factors for Autism Spectrum Disorder

<p dir="ltr"><b>Background</b> Autism Spectrum Disorder (or Autism) is a neuro-developmental and neurological condition, with prevalence of 1 in 100 children globally. Whilst exact aetiology is unknown, there are several factors associated with an increased risk of Autism in children. This review examines the most common factors associated with Autism. </p><p dir="ltr"><b>Methods</b> We conducted a scoping review of factors associated with Autism. These included genetic predisposition, parental age, gender, birth complications and multiple morbidities due to other medical conditions. </p><p dir="ltr"><b>Results</b> Evidence from twin studies shows a 90% genetic predisposition towards Autism – with 102 genes strongly associated with Autism, including SCN1A and SLC6A1. There are also genetic syndromes and chromosomal disorders associated with Autism, including Fragile X syndrome and Tuberous Sclerosis complex (TSC). Several studies have demonstrated an increased risk with advanced parental age (>35 years) (e.g., fathers >50 years are 2.2 times more likely to have a child with Autism than those <30 years). Other prenatal factors include infections and exposure to traumatic events during pregnancy (e.g. immune dysfunction) and gestational diabetes. Birth complications, such as prematurity, low birth weight (<1500g) and extremely pre-term to very pre-term gestational age (<32 weeks) are also associated with an increased risk of Autism. Abnormalities in brain development during early prenatal or postnatal periods may increase the risk of Autism. Gender has been explored, with boys being more likely to be diagnosed with Autism – gender ratio of 3:1 and 4:1 has been reported in different populations. </p><p dir="ltr"><b>Conclusions</b> Autism is a complex and heterogeneous condition that likely arises from a combination of risk factors such as genetic susceptibility and pre- and postnatal factors. An understanding of these factors is important for early detection, intervention, and support for children to improve their quality of life and reduce morbidity.</p>