solute carrier family 37 member 4
The SLC37A4 gene provides instructions for making a protein called glucose 6-phosphate translocase. This protein transports the sugar molecule glucose 6-phosphate from the fluid inside the cell (cytoplasm) to the endoplasmic reticulum, which is a structure inside cells that is involved in protein processing and transport. At the membrane of the endoplasmic reticulum, glucose 6-phosphate translocase works together with the glucose 6-phosphatase protein (produced from the G6PC gene) to break down glucose 6-phosphate. The breakdown of this molecule produces the simple sugar glucose, which is the primary energy source for most cells in the body.
More than 80 mutations in the SLC37A4 gene have been found to cause glycogen storage disease type Ib (GSDIb). Most of these mutations change single protein building blocks (amino acids) in glucose 6-phosphate translocase. SLC37A4 gene mutations disrupt the normal functioning of glucose 6-phosphate translocase and prevent the transport of glucose 6-phosphate to the endoplasmic reticulum. If glucose 6-phosphate cannot get to the endoplasmic reticulum, it cannot get broken down and glucose is not produced. Glucose 6-phosphate that is not broken down to glucose is converted to fat and glycogen, a complex sugar that is stored within cells. Too much fat and glycogen stored within a cell can be toxic. This buildup damages organs and tissues throughout the body, particularly the liver and kidneys, leading to the signs and symptoms of GSDIb. For reasons that are unclear, mutations in the SLC37A4 gene also cause a shortage of white blood cells (neutropenia) in people with GSDIb.
- glucose-6-phosphate translocase
- solute carrier family 37 (glucose-6-phosphate transporter), member 4