What are the genetic changes related to COG5-congenital disorder of glycosylation ?
COG5-CDG is caused by mutations in the COG5 gene, which provides instructions for making one piece of a group of proteins known as the conserved oligomeric Golgi (COG) complex. This complex functions in the Golgi apparatus, which is a cellular structure in which newly produced proteins are modified. One process that occurs in the Golgi apparatus is glycosylation, by which sugar molecules (oligosaccharides) are attached to proteins and fats. Glycosylation modifies proteins so they can perform a wider variety of functions.  The COG complex takes part in the transport of proteins, including those that perform glycosylation, in the Golgi apparatus. COG5 gene mutations reduce the amount of COG5 protein or eliminate it completely, which disrupts protein transport. This disruption results in abnormal protein glycosylation, which can affect numerous body systems, leading to the signs and symptoms of COG5-CDG. The severity of COG5-CDG is related to the amount of COG5 protein that remains in cells.