Researchers have found that repeats of certain DNA segments, known as Olduvai repeats, may align with the severity of autism. Olduvai repeats, which were previously known as DUF1220, have been linked to primate brain expansion and are categorized into six main types. One type of Olduvai repeats has previously been associated with autism. The function of these protein fragments encoded by Olduvai repeats is uncertain but may contribute to neuron generation. Humans carry 250-350 Olduvai repeats, while nonhuman primates have around 100, apes have about 100, and monkeys have 30-40. These repeats may have played a role in driving brain size increase during primate evolution.
In a recent study, it was discovered that a duplication of a specific region in the genome, called CON1, doubles the number of Olduvai repeats and is associated with autism. Whole-genome sequencing of 215 individuals with autism revealed that they carry between 61 and 84 copies of CON1. Men with more copies of CON1 tend to struggle more with social interactions and communication. The number of repeats in CON1 predicts social and communication abilities in individuals with autism.
Furthermore, specific genes implicated in autism, such as NBPF1 and NBPF14, contain repeats within them. NBPF1 contains several CON1 repeats, while NBPF14 carries a different type of repeat called HLS1 within the 1q21.1 region. Repeats in NBPF14 and HLS1 are linked to the severity of autism. These findings suggest that regions involved in brain evolution may predispose individuals to autism.
The study also found that Olduvai repeats, particularly HLS1, are linked to autism severity in families with multiple affected members, indicating that these repeats may have implications for the inherited risk of autism. However, there are still many unknowns regarding the exact mechanisms behind these DNA repeats and their impact on health.
Overall, these findings connect brain evolution, intelligence measures, and neurodevelopmental disorders like autism. Further research is needed to uncover the differences in Olduvai repeats between individuals with autism and those without, and to understand the precise mechanisms by which these repeats affect autism severity.
