The Influence of Developmental Dyslexia-associated Gene KIAA0319 on Brain Development——From Animals to Humans / 生物化学与生物物理进展

ABSTRACT

Developmental dyslexia (DD) is a prevalent learning disorder, and the KIAA0319 gene is a DD-associated gene, potentially affecting reading ability by influencing brain development. This review provides an overview of the impact of KIAA0319 gene on brain development in fish, non-primate mammals, primate mammals, and humans. In studies involving fish, the kiaa0319 gene was found to be expressed in the brain, eyes and ears of zebrafish. In mammalian studies, abnormal Kiaa0319 gene expression affected neuronal migration direction and final position, as well as dendritic morphology during embryonic development in rats, leading to abnormal white and gray matter development. Knocking down the Kiaa0319 gene impaired the primary auditory cortex in rats, resulting in phoneme processing impairment similar to DD. In mice, Kiaa0319 overexpression affected the neuronal migration process, causing delayed radial migration of neurons to the cortical plate. Knockout of the Kiaa0319 gene led to abnormal development of the gray matter in mice, resulting in reduced volume of the medial geniculate nucleus and then impacting auditory processing. In primate studies, research on marmosets found that KIAA0319 gene is expressed in the visual, auditory, and motor pathways, while studies on chimpanzees revealed that KIAA0319 gene abnormalities primarily affected the gray matter volume and microstructure of the posterior superior temporal gyrus, morphology of the superior temporal sulcus and gray matter volume of the inferior frontal gyrus. The impact of KIAA0319 gene on human brain development is mainly concentrated in the left temporal lobe, where abnormal KIAA0319 gene expression caused reduced gray matter in the left inferior temporal gyrus, middle temporal gyrus and fusiform gyrus, as well as reduced white matter volume in the left temporoparietal cortex. Abnormalities in KIAA0319 gene also led to decreased hemispheric asymmetry in the superior temporal sulcus. The above-mentioned brain regions are crucial for language and reading processing. It is analyzed that the abnormalities in the DD-associated KIAA0319 gene affect neuronal migration and morphology during brain development, resulting in abnormal development of subcortical structures (such as the medial geniculate nucleus and lateral geniculate nucleus) and cortical structures (including the left temporal cortex, temporoparietal cortex and fusiform gyrus) which are involved in human visual and auditory processing as well as language processing. Impairment of the medial geniculate nucleus affects the information transmission to the auditory cortex, leading to impaired phoneme processing. Abnormalities in the magnocellular layers within the lateral geniculate nucleus hinder the normal transmission of visual information to the visual cortex, affecting the dorsal visual pathway. The left temporal lobe is closely related to language and reading, and abnormalities in its gray matter and connections with other brain areas can affect the language and word processing. In summary, abnormalities in the KIAA0319 gene can partly explain current research findings on the cognitive and neural mechanisms of DD, providing a genetic basis for theoretical models related to DD (such as general sensorimotor theory and the magnocellular theory). However, the mechanism of developmental dyslexia is complex, and there are mutual influences between different DD-associated genes and between genes and the environment, which require further exploration.