What is the function of chromosome 8? Chromosome 8 spans about 145 million base pairs (the building material of DNA) and represents between 4.5 and 5.0% of the total DNA in cells. About 8% of its genes are involved in brain development and function, and about 16% are involved in cancer. What is chromosome 8 deletion? 8p23 deletion syndrome. An 8p23 deletion means that the cells of the body have a small but variable amount of genetic material missing from one of their 46 chromosomes – chromosome 8. For healthy development, chromosomes should contain just the right amount of material – not too much and not too little. What happens when a chromosome is deleted? Chromosomal deletion syndromes result from loss of parts of chromosomes. They may cause severe congenital anomalies and significant intellectual and physical disability.