Genetic architecture of patients with autism spectrum disorder - data analysis based on the literature review

Autism spectrum disorder (ASD) is a neurodevelopmental condition including incorrect functioning in communication, social interaction, and repetitive behavior. Global prevalence is estimated as 1-2%, with a predominance of men. Different pre- and perinatal, environmental, immunological, neurobiological, genetic, and epigenetic factors are involved in the etiology of ASD. The study aims to analyze genetic abnormalities in patients with ASD according to data from the current literature.

Studies available in the PubMed and Google Scholar databases were chosen through a literature search. Only papers published from 2020, available as full-text publications in English, with studies conducted on humans, original papers, or meta-analyses were included.

The following types of genetic variation were identified: copy number variants, larger insertions, inversions, uniparental disomies, tandem repeat expansions, common single nucleotide polymorphisms, single nucleotide variants, short insertions/deletions, and mitochondrial variants. Epigenetic factors, like histone modifications, deoxyribonucleic acid (DNA) methylation, and micro ribonucleic acid might play an important role in ASD predisposition. Genes identified in the review were mainly involved in neurodevelopment, synaptic formation, neuronal migration, neurotransmission, glial proliferation, ubiquitination, chromatin remodeling, or transcription. ASD is described as a component of the phenotype in fragile X syndrome, tuberous sclerosis complex, neurofibromatosis type 1, Angelman, Phelan-McDermid, Smith-Lemli-Opitz syndromes, and chromosome trisomies. Current guidelines for genetic diagnosis of ASD recommend performing directed genetic studies in the first line (like multiplex ligation-dependent probe amplification - MLPA, analysis of FMR1 gene), in case of a negative result, chromosomal microarray as a routine method, then next-generation sequencing (NGS) panel testing, WES (whole exome sequencing), or even WGS (whole genome sequencing) as the last test.

Wider access to modern diagnostic methods has increased the number of ASD patients in whom the genetic etiology of the disorder has been uncovered. Knowledge of the genetic background would be applicable in the diagnosis, prevention, prognosis, and individualized treatment.