What type of mutation causes autism?

Autism spectrum disorder (ASD) has a complex genetic background, and various types of mutations can contribute to its development. Multiple genes are involved, each mutation might have different effects, and combinations of mutations from different genes are also possible. Here are some types of genetic changes associated with ASD:

Single-nucleotide variations (SNVs): These involve substitutions, deletions, or insertions of a single nucleotide in the DNA sequence, altering the coding of a single gene.

Copy number variations (CNVs): These are gains or losses of larger segments of DNA, sometimes including multiple genes.

De novo mutations: These are mutations that arise spontaneously and are not inherited from either parent. These are thought to play a significant role in ASD with incomplete penetrance and variable expressivity. Mutations affecting genes related to neuronal development, neural connectivity, synapse function, and chromatin remodeling have been implicated.

Chromosomal rearrangements: These involve structural changes in chromosomes, such as deletions, duplications, translocations, or inversions. Fragile X syndrome, caused by abnormalities in the X chromosome, is one known example linked to ASD.

Genome-wide association studies (GWAS) have identified several common genetic variants associated with an increased risk of ASD. While these variants may have small individual effects, collectively they contribute to the genetic basis of the disorder.

Studying the genetics of ASD is challenging due to the heterogeneity and complexity of the condition. Mutations affecting various genes and gene networks may converge on similar functional pathways involved in neural development and brain function.