ALL1-fused gene from chromosome 1q (AF1q) is a novel gene that encodes a 90-amino-acid protein that is unlike any other known proteins. AF1q was first discovered as a fusion partner for mixed-lineage leukemia in a pediatric acute myeloid leukemia. Since its discovery, AF1q has been found to act as an oncogene and has been linked to several solid neoplasms, including thyroid oncocytic tumors, breast cancer, testicular cancer, and colorectal cancer. AF1q is also upregulated in several hematological malignancies and is considered an adverse prognostic factor. In addition, AF1q is expressed in various regions of the brain throughout human neural developmental processes. The expression levels of AF1q and neuron-specific class III β-tubulin (Tuj1), a marker of post-mitotic neurons, are positively correlated in the cerebral cortex. AF1q expression also induces the transformation of human embryonic kidney cells into neurons, indicating that AF1q may play a key role in neuronal differentiation during normal neural development. The activity of AF1q is regulated by RE1-silencing transcription factor (REST), an important regulator of embryonic and neural stem cells during normal development. Furthermore, AF1q is associated with the activity of the Wingless/Integrated (Wnt) signaling pathway, which is critical to normal development of the nervous system. Although the precise role of AF1q is yet to be uncovered, various studies have demonstrated that AF1q is indeed heavily involved in neurodevelopmental processes. The investigation of the role of AF1q in neurodevelopment is important for several reasons. First, it can give a better understanding of the biological and physiological functions of AF1q, a gene that is still poorly understood. Second, it can provide insight into the development of the human nervous system and the complex processes and regulations that are involved. Through the study of AF1q in a neurobiological context, its precise role in neural development may be uncovered, and new therapeutic approaches to neurodevelopmental disorders such as Down syndrome and Alzheimer’s disease may be possible.